Technical support – DDPROTOTYPE

CNC Machined Materials

Martin.mu — Wed, 12 Jun 2024 07:40:23 +0000

DDPROTOTYPE is pleased to introduce six CNC machined materials: four metals and two plastics. In addition to aluminum, there are three kinds of stainless steel alloys, acrylic, HDPE, 7075 aluminum, brass, 17-4 PH stainless steel, 1018 low carbon steel.

At DDPROTOTYPE, we use advanced equipment to provide you with various CNC machining services, including milling, turning, EDM, WEDM, surface finishing, etc. With our imported 3 axis, 4 axis, and 5 axis CNC machining centers, our skilled machinists can use a variety of plastic and metal materials to make turning and milling parts. Our CNC machining capability also complements our 3D metal printing service, making us an excellent one-stop service for your advanced design.

1. acrylic

Overview: scratch resistant plastic material.
Common applications: tanks, panels and optical applications.
Color: optically transparent, opaque
Appearance: transparent or opaque when not finished. After processing, transparent acrylic will present a frosted, translucent appearance, although it can be smoothed to an optically transparent state again using various finishing methods.
Design note: it may be a little brittle in thin-walled areas, so it is not recommended for delicate or complex geometry.

2. High density polyethylene

HDPE CNC processing materials
Overview: plastic material is excellent electrical insulator, and has moisture-proof and chemical corrosion resistance.
Common applications: often machined into plugs and seals
Color: white
Appearance: due to its crystal structure, HDPE is naturally opaque white, but it can also be dyed black, and the inventory is limited. It has a wax coating and is very suitable for low friction applications.

3.7075 aluminum

7075 aluminum alloy CNC machining materials
Overview: hard, high strength alternative 6061 aluminum.
It is also corrosion-resistant, non-magnetic and heat treatable.
Finish: untreated aluminum usually has a dull silver / grey finish, depending on the surface roughness. Aluminum can be anodized, sandblasted and hand polished to achieve a variety of surface finishes.

4.360 brass

Brass CNC material
Overview: due to the highest lead content in brass alloy, it is also called free machining brass. This material has excellent machinability, which means minimal tool wear.
Common applications: gear, lock components, pipe fittings and decorative applications
Surface treatment: the glossy yellow surface changes according to the surface roughness. It can be hand polished to add luster (think small or saxophone), or sandblasted to get more matte texture.

5. 17-4 PH stainless steel

17-4 PH stainless steel CNC processing material
Overview: materials with high strength and high corrosion resistance can keep their durability below 1100 ° F. The name pH stands for precipitation hardening, which is treated to improve yield strength. It can be magnetic and heat treated, and its hardness is about Rockwell C50.
Surface treatment: the surface treatment of stainless steel varies greatly according to the surface roughness, but it is usually characterized by its luster, darker color and more silver than the unfinished aluminum alloy.
Stainless steel can be powder coated, electroplated, polished or sandblasted to achieve a variety of surface effects.

6. 1018 low carbon steel

1018 low carbon steel numerical control processing material
Overview: cost effective and highly Machinable, weldable and useful without the need for high strength.
Common applications: clamps and mounting plates
Surface treatment: the surface treatment of 1018 steel is similar to that of stainless steel: the surface is usually glossy, slightly darker than that of aluminum alloy. Stainless steel can also be medium sandblasted, hand polished and powder coated to achieve a variety of surface treatments.

3 -axis, 4 -axis, and 5-axis CNC machining services, including milling, turning, EDM, and wire cutting EDM. Suitable for aluminum, steel, stainless steel, magnesium, titanium, zinc, brass, bronze, copper, ABS, Polycarbonate, Polypropylene, Polystyrene, POM, PMMA, PAGF30, PCGF30, PTFE, DHPE, HDPE, PPS and Peek.

DDPROTOTYPE provides CNC turning functions, such as end face, thread, drilling, boring, reaming and taper turning. Capable of machining CNC milled parts with a tolerance of + / -0.005 mm. Prototype and production run. Suitable for functional prototypes, gaskets, manifolds, accessories, shafts, bushings and circuit boards. Serve the automotive, aerospace, medical and consumer electronics industries. On time delivery.

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Drilling and Tapping

Martin.mu — Tue, 11 Jun 2024 20:39:07 +0000

Do you have any ideas on how to better design the drilling and tapping on the prototype?CNC machinist of DDPROTOTYPE has a lot of machining experience. He should sort out some guidelines and answer all questions about how to add threaded holes to parts.

What is the difference between drilling and tapping?

Drilling and tapping are two different actions. Drilling is the use of a drill to create a smooth hole in the material. Tapping is the action of producing a thread on the side of a hole.Various types of taps to match almost all available screw types, including metric and standard sizes. Select tap information including thread number, diameter, pitch and coarse fine thread. Tap guides are essential for creating straight and usable taps. When tapping on a machine such as a CNC milling machine or lathe, the tap will be automatically centered and straight. Please pay attention to the tap alignment when performing manually, because the human eye is not as accurate as the perfect 90 degree tap guide.

Use oil

Oil must be added when drilling and tapping. It prevents overheating, helps to remove chips from the bit, helps to cut, and prevents the bit from being squeezed.

Center drill

To create a drill and tap hole first, you need to use a center drill. This provides a center of alignment for larger bits because most bits are not fully centered when installed in the bit chuck. This ensures that the larger bit is drilled in the correct position and does not cross the part.

Pecking holes

Whether drilling or tapping, pecking helps ensure that the bit does not overheat or break. Pecking is a way to drill into a part, then back off to remove chips and cool the part. The usual way to do this is to rotate the handle for one full turn and then half a turn. Remove as much chips as possible and add oil to the surface and bit / tap each time the bit / tap is pulled out.

Power

Be careful not to apply too much downward force. Use the rotating force and tap pecking method to prevent the tap from breaking.

Rule of Thumb

As for the ratio of tapping bit to large diameter of thread, there are some rules of experience with strong prediction ability for standard V thread (ISO V thread and UTS V thread):

The coarse diameter of a good bit is 85% of the large diameter (± 2 PP)

The high quality tap drill should be 90% (± 2PP) of the large diameter.

For metric V threads, the concept of major negative pitch (i.e., the major diameter or maximum diameter of the desired screw in millimeters minus the screw pitch in millimeters per millimeter of the screw) produces a good tap drill diameter.

The main pitch reduction technology is also applicable to inch based threads, but you must first convert the thread per inch (TPI) ratio to a decimal calculated tone. For example, a screw with 1 / 20 in one pitch (20 threads per inch) has a pitch of 0.050 and a pitch of 1 / 13 in pitch (13 lines per inch) has a pitch of 0.077. Your results will only land near the tap size (not directly on one).

For these two rules of thumb (85% / 90% and major negative pitches), yield tap hole size is not necessarily the only possibility, but it is a good choice for general use.

85% and 90% of the rules work best in the range 1 / 4-1 (6.4-25.4mm) when size is most important in many shop floors. Some dimensions outside this range have different ratios.

How do I add threads to my 3D parts?

The short answer is that you don’t have to. In most 3D CAD applications, adding a thread is a time-consuming task and does not require adding a 3D tap to the part. If you want to add threads to some holes in a part, follow these steps
Make sure that the hole matches the pilot drill size required by the tap.
Please refer to which threaded holes and thread types and pitches in your ordering instructions or references.
If you need to customize thread depth, add any comments.

Can my parts be made of custom thread?

Usually, but it depends on the diameter. Tapping holes can be made with traditional taps, which are tools for standard thread sizes, or with a thread cutter, which is a small disc for cutting threads through the XYZ motion of a CNC controller. The diameter of the cutter is limited to more than 1 / 2 inch. Custom lines can be made with a tangent knife, but this may incur additional costs.

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Aluminum and Steel Tooling

Martin.mu — Mon, 10 Jun 2024 22:07:14 +0000

Aluminum and steel tooling are often used in two forms, each with its own advantages, but aluminum tooling are an ideal alternative to steel molds. Aluminum tools can reduce cycle time and costs. Today, aluminum tools have many advantages that make them a viable option. What are these benefits?

1. Aluminum is easier to cut than steel, so it can be machined faster and lead times reduced.

2 .Although aluminum is considered too soft for mass production, this is not the case. Some aluminum molds are capable of producing parts after 2 million cycles!

3 .Aluminum cools much faster than steel. This reduces cycle time and saves costs.

4 .Since aluminum is very light, it can be machined faster on smaller equipment.

5 .Aluminum dissipates heat at a very uniform rate, and because of its small deformation, it has great stability to dimensions.

6 .Much less scrap because there are far fewer cracks and warps.

Aluminum is often considered a weak material and is not conducive to mass production. However, aluminum can actually be used for mass production. It can also process faster than Steel and dissipate heat at a faster or even faster rate. As a result, delivery times are often shortened and money is saved.

As for the service life of aluminum tools, the surface coating can extend the already impressive service life. Many companies are now using aluminum for production, not just prototype work.

DDPROTOTYPE offers low cost aluminum and steel molds. Most of our plugins are made of aluminum. Our in-house capabilities shorten lead times for molds and respond quickly to mold modifications.

Our understanding of the benefits of aluminum molds has helped our customers save time and money. Email us today to see if aluminum molds can do the same for you!

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Manufacturing Standards

Martin.mu — Mon, 10 Jun 2024 13:30:48 +0000

DDPROTOTYPE manufacturing standards to help you optimize the design of the manufacturing method of your choice.Unless we agree with the other tolerances in your quote, we will strive to achieve and maintain the tolerances described below, which will vary depending on the main manufacturing method you choose.

CNC Machining

By default, sharp edges are destroyed and deburred. Care must be taken and specified on the print that the critical edge must be sharp.
Suitable for size (length, width, height, diameter) and position (position, concentricity, symmetry) +/- 0.005 “.
For directional (parallelism and perpendicularity) and shape (cylindrical, flatness, roundness, and straightness) features, the following tolerances apply:

Vacuum casting

Typical values are +/- 0.010 “or +/- 0.003” per inch, whichever is greater. Irregular or excessively thick geometries can cause deviations or deflections due to shrinkage.
Due to the thermal expansion of the liquid and the response of the flexible mold, a shrinkage rate of + 0.15% can be expected.
The surface finish is smooth on the outside to a satin or matte surface. Growth lines may exist on internal or hard-to-access features. Polished or custom finishes must be clearly defined and agreed upon when ordering.
We can provide polyurethane castings up to 30 inches.

SLA-Stereolithography

Tolerances for standard resolution:
X / Y plane: typically the first inch is +/- 0.005 “, and thereafter plus +/- 0.002” per inch.
Z-Plane: Typical first inch is +/- 0.010 “, and thereafter plus +/- 0.002” per inch.
Minimum linear feature size: Below 0.030 “at risk and below 0.020” will not be constructed.
Minimum radial feature size: 0.035 “
Tolerances are guaranteed through manual quote reviews and must be approved on a case-by-case basis.

High-resolution tolerances:

X / Y plane: typically the first inch is +/- 0.005 “, and thereafter plus +/- 0.002” per inch.
Z-Plane: Typical first inch is +/- 0.010 “, and thereafter plus +/- 0.002” per inch.
Minimum linear feature size: Below 0.020 “at risk, below 0.010” will not be constructed.
Minimum radial feature size: 0.030 “
Tolerances are guaranteed through manual quote reviews and must be approved on a case-by-case basis.

SLS-Selective Laser Sintering

A typical first inch is +/- 0.005 “, and thereafter plus +/- 0.002” per inch.
Parts with thicker geometries, flat or wide parts, and parts with uneven wall thickness will be prone to significant deviations or warping due to variable heat shrinkage and stress.
Tolerances are guaranteed through manual quote reviews and must be approved on a case-by-case basis.

Plastic Injection molding

The lead time mentioned is the first shipment. Confirm the remaining production time after approval of the first article.
A typical first shipment is 10 pieces.
Perfect color matching of Pantone colors cannot be completely guaranteed.
All quotes are based on the design’s core assumptions of adequate draught, radius and manufacturability.
Unless explicitly discussed, core, side effects, and tool strategies are determined by DDPROTOTYPE.
Unless otherwise stated, tolerances between manufactured parts and 3D CAD are +/- 0.010 “. Part-to-part repeatability is typically below 0.004”.
Unless explicitly discussed, gating, ejection, braiding and parting lines are at the discretion of DDPROTOTYPE.

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Regarding Anodizing Aluminum at Home

Martin.mu — Sat, 01 Jun 2024 14:03:05 +0000

Anodizing aluminum parts can be a reliable means of adding boosted mechanical properties to components or improve their aesthetics. Lots of people don’t know just how to anodize aluminum, although the process is relatively easy. Read on to find out more regarding anodizing aluminum at home or in a production factory operation.

Why You Might Intend To Anodize Aluminum

There are numerous excellent reasons to consider anodizing your aluminum components. When plating aluminum, a layer of oxide is developed and develops a layer on the aluminum’s surface. This layer is so thin that it doesn’t even materially affect the dimensions of precision machined components. Because the oxide layer is harder than the aluminum, it safeguards the metal underneath it, making it scratch-resistant and increasing deterioration resistance.

The oxide layer is additionally rougher than the aluminum surface area, making it possible to paint or color the anodized aluminum. In fact, you can add any kind of color you such as to anodized aluminum parts. Coloring is completed either by utilizing dyes throughout the anodizing process or by painting later. Dying is favored, as it creates permanent pigmentation which indicates it will not fade and also can’t be scratched off.

Advantages of Anodizing Aluminum Parts

Plating aluminum parts provides lots of benefits, both in regards to aesthetics and also the mechanics of the components themselves.

On the visual side, the effects are quite excellent and the coating is long-term. It is wear-resistant so it will never damage or fade and also will certainly never ever require a touch-up. And also, it’s eco-friendly.

On the mechanical side, the anodizing process makes the surface of the parts exceptionally resilient. The oxide is extremely hard and also supplies exceptional abrasion as well as corrosion defense. The thermal insulation buildings are additionally superior.

In general, the procedure makes components look much better and extra durable. Plus, the procedure is extremely cost effective, even if you’re the enthusiast as well as the type of individual that will be going to do it on your own in your home.

Products Needed to Anodize Aluminum

The materials you’ll need to plate are rather fundamental and not also pricey. If you believe you’ll be doing this rather consistently, it makes good sense to establish a house anodizing station.

Here's what you'll require:

Sulfuric acid
Pure water
Numerous containers (containers) to hold the liquids
A cathode
Aluminum cable (titanium will certainly also function).
Degreaser.
Lye.
Acid neutralizer.
A power source.
Dye (if you desire a tinted part).

You will likewise require a well-ventilated location to set up your anodizing station, along with individual security gear (eye security, handwear covers, respirator, etc).

Along with the needed materials above, you might additionally wish to purchase some optional products to make your job much easier. These consist of the following:.

An agitator for the acid bathroom.
Scotch-Brite pads for cleaning parts prior to anodizing.
Sound pong spheres (put in the storage tank to prevent acid mist).
Affordable tea kettle to warmth color.
Aquarium heating unit to manage storage tank temperature level.
Food preparation thermostat for checking temperatures.

Just How to Plate Aluminum in your home.

Below are the basic detailed directions to follow for the at-home hobbyist to anodizing aluminum parts yourself. Please keep in mind that it does take time to grasp the process, and your materials may require some tweaks.

Utilize the Scotch-Brite pad to cleanse the surface as well as get rid of any machining marks.
Put on your safety and security devices, consisting of handwear covers.
Use the degreaser to clean up the part well, then rinse with the distilled water.
Engrave the component by dipping in a lye bathroom for 3-5 minutes. Use roughly 4 tablespoons of lye to 1 gallon of water.
Eliminate from the lye bath and also rinse with distilled water.
Look for cleanliness by pouring water on the piece. If tidy, the water must runoff. If the water beads externally, the part is unclean sufficient for plating.
Rack the part by protecting it to the aluminum (or titanium) wire. Guarantee the link is excellent, and do not fail to remember there will be an unanodized mark where the cord touches with the part.
Develop the bath by adding sulfuric acid to the pure water in your anodizing container at a ratio of 1 part acid to 3 parts water. Note that anodizing is most successful when the bathroom temperature is 70 degrees Fahrenheit. Anything over 75 F or listed below 65 F will not produce good outcomes.
Currently every little thing goes in the tank. Add the cathode, ensuring it won’t touch the part( s). Include the agitator. Suspend your components in the container, making certain they aren’t touching anything.
Include the heating unit and also thermostat. Add the ping pong balls to cover the surface.
Make sure the temperature level is 70 levels prior to proceeding.
Set up your power supply as well as link the favorable terminal to the wire affixed to the component( s). The adverse side is connected to the cathode. Currently points can obtain sensitive.
The amperage is set based upon the overall surface being plated. For a great, difficult surface area, use 0.03 amps per square inch, and also for a softer surface area that will take dye better, use 0.02 amps per square inch.
Beginning at 16 volts. You can locate all kind of online calculators, however a home arrangement beginning at 16 volts need to get you pretty close. Keep an eye on the tank temperature as the process accompanies. The temperature can enhance when the procedure is underway.
While the anodizing procedure is going on, warm your dyes. For the majority of colors, 140 ° F works best for most shades, however some work better at cooler temperatures. You’ll need to try out your brand names as well as colors.
Prepare one tank of pure water and an additional with your acid neutralizer.
Turn off the power as well as eliminate your parts from the anodizing container. Dip first in the distilled water for 10-15 seconds, then rinse in the acid neutralizer container for 5 mins. Wash a second time in the pure water and also dunk the parts in the color. They must immediately start to take the color, however make sure to leave the parts in the dye for 10-15 minutes, relying on exactly how deep you desire the color to be.
After completed with the color, you wish to steam the parts for 15 minutes. Boiling hardens and seals the dye.

Anodizing in your home is achievable for the layman, but lots of various other steel manufacture processes like creating, stamping, and extrusion call for a professional producer. If you call for customized metal items and procedures, contact info@ddprototype today.

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Cautions CNC machining shaft parts

Martin.mu — Sat, 01 Jun 2024 11:04:25 +0000

What is shaft parts

Shaft part is a common type of parts, its structure is a rotating body and the length is greater than its diameter generally. It’s widely used in supporting transmission parts, transmission torque and load to bear for various mechanical equipments. The machining of Shaft parts must follow certain rules. Here list out some CNC machining tips & machining cautions of shaft parts.

Basic processing route of shaft parts

The main processing surface of shaft parts is the cylindrical surface and the common special-shaped surface. Therefore, select most suitable processing method for various requirements of accuracy levels and surface roughness. The basic processing route can be summarized into the following four points.

The first type of processing route is from rough turning to semi-finishing turning and then finish turning, which is the mainly processing route option for the outer circle processing of shaft parts with common materials.

The second type of processing route is from rough turning to semi-finishing turning, then to rough grinding and finally takes fine grinding. For ferrous metal materials (such as mold steel, alloy steel, or hardened materials after heat treatment, etc.), and the part need to do quenching treatment with highly requirements of accuracy and surface roughness, such processing route will be the best option, as grinding processing is ideal choice for the strict requirements of surface roughness.

The third type of processing route is from rough turning to semi-finishing turning, then to finish turning and diamond turning. Such kind of processing route is dedicated to use for machining non-ferrous metal material (aluminum, brass, etc), as the hardness is low for non-ferrous metal material and easy to block the gaps between sand grains. Usually using grinding processing can’t meet the requirement of the surface roughness and have to take finish turning and diamond turning.

The last type of processing route is from rough turning to semi-finish turning, then rough grinding, fine grinding, and finally polishing processing. Such processing route usually applied for the ferrous metal materials after quenching treatment, and the parts also with highly requirements of accuracy and surface roughness.

Pre-processing of shaft parts

Before turning the outer circle of shaft parts, there are some preparatory processes must be carried out which called pre-processing of shaft parts. The most important preparatory process is straightening. As the workpiece blank usually got deforming during the manufacturing, transportation and storage process. In order to make sure reliable clamping and evenly distributed of machining allowance, will take straightening process through various presses or straightening machines in the cold state.

Locating datum for machining shaft parts

Firstly, use the center of the workpiece as CNC machining locating datum. In the processing of shaft parts, the coaxiality of various cylindrical surfaces, taper holes, threaded surface and the perpendicularity of end faces to the rotary shaft line are important manifestation of location accuracy. Those surfaces are generally based on the centerline of the shaft as the design reference, and use center line for positioning which conform to the principle of criteria coincidence. The center line is not only limited to as the locating datum of CNC turning, but also as the locating datum and inspection datum for other machining processes, and conforms to the principle of datum unification. When two center holes are used for locating, it can maximize machining of multiple outer circles and end faces in one clamping.

Secondly, use the outer circle and center hole as CNC machining locating datum. Such method effectively overcomes the shortcomings of poor rigidity center hole locating, especially machining the heavy workpiece, the center hole locating will easy lead unstable clamping, and cutting parameters can’t be large also. And use the outer circle and center hole as CNC machining locating datum can avoiding such problem happens. During the rough turning, use the outer circle and center hole as CNC machining locating datum can withstand the larger cutting torque during turning processing, which is common locating method for shaft part machining.

Thirdly is using the two outer circle surfaces as CNC machining locating datum. When processing the inner hole of the hollow shaft, the center hole cannot be used as location datum, so we have to use the two outer circle surfaces as location datum. When machining the main shaft of a machine tool, the two supporting journals are often used as the locating datum, which can effectively guarantee the coaxiality requirements of the tapered hole relative to the supporting journal, and eliminate errors caused by datum misalignment.

Finally is use the taper with the center hole as CNC machining location datum. Such method is most commonly used in the outer circle surface turning of the hollow shaft parts.

Clamping of shaft parts

The processing of the taper and taper center shaft must with highly machining accuracy, the center hole is not only the locating datum of its own manufacturing, but also the datum for finish turning the outer circle of the hollow shaft, which must ensure the taper and the taper surface of tapper center shaft have highly coaxiality with the center hole. Therefore, when choosing the clamping method, it should be noted that the number of taper installations should be reduced as much as possible, which aim for reduce the errors caused by repeat install the parts. In actual machining, after the taper installed, generally speaking, it will not be removed or replaced in the middle of processing until the processing is completed.

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Method for Selecting Positioning Datum for CNC Machining Parts

Martin.mu — Sat, 01 Jun 2024 08:54:45 +0000

During CNC machining process, the selection of the Positioning datum determines the quality of the parts, and it plays a decisive role in ensuring the dimensional accuracy and mutual position accuracy of the parts. At the same time, it also has a great influence on the processing sequence between the surfaces of the parts. When using a fixture to install the workpiece, the choice of positioning datum will also affect the complexity of the fixture structure, because this requires the fixture to withstand large cutting forces and meet the positioning accuracy requirements. Therefore, the choice of positioning datum is a very important factor affecting the CNC machining process. So how do we choose the positioning datum when machining parts with a CNC machining center? Here is a brief introduction:

1.Ensure the Accuracy of The Positioning

The selected datum should be able to ensure the accuracy of the positioning of the workpiece, and it is convenient to load and unload the workpiece, and the positioning and clamping of the workpiece can be completed quickly, the clamping is reliable, and the fixture structure is simple enough to make.

2.Minimize the Calculation of The Dimensional Chain

The selected datum of the CNC machining center and the dimensions of each processing part are simple to calculate, minimize the calculation of the dimensional chain, and avoid or reduce the calculation links and calculation errors.

3.To ensure the accuracy of various processing, following principles should be followed When determining the positioning datum of specific parts:

1) The origin of the workpiece coordinate system, also named the “programming zero point”, do not necessarily have to coincide with the positioning datum of part made, but there must be a definite geometric relationship between the two. The main consideration for the selection of the origin of the workpiece coordinate system is to facilitate programming and measurement. For parts with high dimensional accuracy requirements, when determining the positioning datum, it should be considered whether the coordinate origin of the CNC machining center can be accurately measured by the positioning datum.

2) When both the processing datum and the processing of each station are completed on the CNC machining center, the selection of the positioning datum needs to consider the completion of as much processing content as possible. For this reason, it is necessary to consider a positioning method that facilitates all surfaces to be processed. For example, for a box, it is best to use a fixed two-sided positioning method to facilitate the processing of other surfaces by the tool.

3) Try to choose the design datum on the part as the positioning datum. This requires that when rough CNC machining, consider what rough machining datum to use to machine each surface of the precision-machined datum, that is, each positioning datum used on the CNC machining center should be processed in the previous ordinary machine tool or other machine tools, so it is easy to ensure the accuracy of the correlation between the processed surfaces of each station.

4) When the positioning datum of the part machined from CNC machining center is difficult to overlap with the design datum, the assembly drawing should be carefully analyzed to determine the design function of the part design datum, and the geometric tolerance range between the positioning datum and the design datum should be strictly specified through the calculation of the dimensional chain to ensure machining accuracy.

5) When the station processing including the design datum cannot be completed on the CNC machining center at the same time, the positioning datum and the design datum should be overlapped as much as possible. At the same time, it should be considered that after positioning with this datum, all the critical precision parts can be processed with one clamping.

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Tips for Controlling The Precision of Part In CNC Machining

Martin.mu — Sat, 01 Jun 2024 05:34:29 +0000

CNC machining precision is the degree to which the three geometric parameters of the actual size, shape and position of the surface for the processed part conform to the ideal geometric parameters required by the drawing. Ideal geometric parameters are the average size for dimensions; for surface geometry, they are absolute circles, cylinders, planes, cones, and straight lines and so on; for the mutual positions of surfaces, they are absolutely parallel, Vertical, coaxial, symmetrical, etc. The deviation of the actual geometric parameters of the part from the ideal geometric parameters is called the machining tolerance. The deviation of the actual geometric parameters of the part from the ideal geometric parameters is called the machining tolerance.

1.The Concept of CNC Machining Precision

Machining precision is mainly used for the degree of product production，CNC Machining precision and machining error are terms used to evaluate the geometric parameters of the machined surface. Machining precision is measured by tolerance grade, when the tolerance grade value is smaller and stands for the precision is higher; the machining error is expressed by a numerical, when the numerical is larger which stand for the machining error is greater. Highly machining precision means machining error is tiny, and vice versa. According to the applicable field and effective scope of the standard, it is generally divided into: international standards, such as ISO, IEC are standards established by the International Standardization Organization and International Electrotechnical Commission; regional standards, such as EN, ANSI, DIN, are respectively the European Union, the United States, Standards developed by Germany.

Tolerance Level

There are total of 20 tolerance levels from IT01, IT0, IT1, IT2, IT3 to IT18. IT01 indicates the highest machining precision of the part, and IT18 indicates the lowest machining precsion of the part. Generally, IT7 and IT8 are middle-level machining precision.

Guaranteed Machining Accuracy

The actual parameters obtained by any machining method will not be absolutely accurate. From the perspective of the function of the part, as long as the machining error is within the tolerance range required by the part drawing, it is considered that the machining accuracy is guaranteed.

Quality of CNC Machines

The quality of the machine depends on the processing quality of the parts and the assembly quality of the machine. The processing quality of the parts includes two major parts, the accuracy of the parts and the surface roughness.

Machining Precision

Machining precision is the degree to which the three geometric parameters of the actual size, shape and position of the surface for the processed part conform to the ideal geometric parameters required by the drawing. The difference between them is called machining error. The size of the machining error reflects the level of machining precision. The machining error is greater stand for the machining precision is lower, and the machining error is smaller stand for the machining precision is higher.

2.Related information for CNC machining precision

Dimensional precision

Dimensional precision refers to the degree of conformity between the actual size of the processed part and the center of the tolerance zone of the part size.

Positional precision

Positional precision refers to the actual position precision difference between the relevant surfaces of the parts after processing.

Shape Precision

Shape precision refers to the degree of conformity between the actual geometry of the surface of the processed part and the ideal geometry.

Interrelationship

Generally, when designing machine parts and specifying the machining precision of parts, attention should be paid to control the shape error within the position tolerance, and the position error should be smaller than the dimensional tolerance. For precision parts or important surfaces of parts, the shape precision requirements should be higher than the position precision requirements, and the position precision requirements should be higher than the dimensional precision requirements.

3.Adjustment method

(1) Adjust the process system
(2) Reduce machine tool errors
(3) Reduce the transmission error of the transmission chain
(4) Reduce cutters wear
(5) Reduce the forced deformation of the process system
(6) Reduce thermal distortion of the process system
(7) Reduce residual stress

4.Cause of impact

（1） Machining principle error

Machining principle error refers to the error produced by processing with approximate blade profile or approximate transmission relationship. The machining principle errors mostly appear in the machining of threads, gears, and complex 3D surfaces.

During machining, approximate processing is generally used to improve productivity and economy on the premise that the theoretical error can meet the processing precision requirements.

（2） Adjustment error

The adjustment error of the machine tool refers to the error caused by inaccurate adjustment.

（3）Machine tool error

Machine tool error refers to the manufacturing error, installation error and wear of the machine tool. Mainly include the guide error of the machine tool, the rotation error of the spindle of the machine tool, and the transmission error of the machine tool transmission chain. This is caused by the machine error of the manufacturing machine, which is also called the industrial master machine. In other words, any actual size is not absolute, only relative. Just like there is no absolute circle in this world, because there is an infinite value behind π3.1415926.

5 .Measurement methods

The machining precision adopts different measurement methods according to different machining precision content and preicison requirements. Generally speaking, there are the following types of methods:

(1) According to whether direct measures the measured parameter, it can be divided into direct measurement and indirect measurement.

Direct measurement: Directly measure the measured parameters to obtain the measured size. For example, use calipers and height gauges to measure.

Indirect measurement: Measure the geometric parameters related to the measured size, and obtain the measured size through calculation.For example: measuring two sizes can get another size.

Auxiliary fixture for measurement：Make the opposite shape to the part for check the assembly size of the part.

Obviously, direct measurement is more intuitive, and indirect measurement is more cumbersome. Generally, when the measured size or direct measurement fails to meet the precision requirements, then has to use indirect measurement.

(2) According to the reading value of the measuring tools whether directly represents the numeric of the measured size, it can be divided into absolute measurement and relative measurement.

Absolute measurement: The reading value directly indicates the size of the measured size, such as measuring with a vernier caliper, micrometer.

Relative measurement：The reading value only indicates the deviation of the measured size from the standard measurement. For example, to measure the diameter of the shaft with a comparator, first you need to adjust the zero position of the measuring tools with a gauge block, then to process the measurement; the measured value is the difference between the diameter of shaft and the size of the gauge block, which is called relative measurement. Generally speaking, the accuracy of relative measurement is higher, but the measurement is more complex. Need to make auxiliary fixture for measurement.

(3) According to whether the surface to be measured is in contact with the measuring head of the measuring tools, it is divided into contact measurement and non-contact measurement.

Contact measurement: The measuring head is in contact with the touched surface, and there is a mechanical measuring force. For example, measure the parts with micrometer.

Non-contact measurement: The measuring head is not in contact with the surface of the measured parts, and non-contact measurement can avoid the influence of the measuring force on the measurement result. For example, use projective Measurement to do the measurement.

（4）According to the number of measurement parameters, it is divided into single measurement and comprehensive measurement.

Single measurement: Measure each parameter of the tested part separately.

Comprehensive measurement: Measure the comprehensive index reflecting the relevant parameters of the part. For example, when using microscope to measure the thread, the actual pitch diameter, the half-angle error of the tooth profile and the cumulative error of the thread pitch can be measured separately.

Generally comprehensive measurement is more efficient and more reliable to ensure the interchangeability of parts, and usually use for inspection of finished parts. Single measurement can determine the error of each parameter separately, and is generally used for process analysis, process inspection, and measurement of specified parameters.

（5）According to the role of measurement in the machining process, it is divided into active measurement and passive measurement.

Active measurement: The workpiece is measured during the machining process, and the result is directly used to control the processing of the part, thus to prevent the defective parts happened.

Passive measurement：Measurement after workpiece completed machining. Such measurement only able to use for judge the workpiece is qualified or not, and is limited to discovering and rejecting defective parts.

（6）According to the state of the measured part in the measurement process, can be divided into static measurement and dynamic measurement.

Static measurement：The measurement is relatively static. Such as measure diameter with micrometer.

Dynamic measurement：During measurement, the measured surface relative motion between the measuring head in the simulated working state.

The dynamic measurement method can reflect the situation when the part is close to usage conditions, which is the development direction of measurement technology.

The post Tips for Controlling The Precision of Part In CNC Machining appeared first on DDPROTOTYPE.

The Application Field of 5-Axis CNC Machining Center And Machiningtips

Martin.mu — Fri, 31 May 2024 23:15:27 +0000

5-Axis CNC machining center with high-tech and high precision and usually applied to mass production of the parts with sculptured surface, complex geometries, multi process and high precision. 5-Axis CNC machining plays a significant role in aerospace, military, scientific research, precision instrument and machinery, high precision medical equipment and so on for every country. Currently, 5-Axis CNC machining is the only means to machining impeller, blade, blade propeller, heavy-duty generator rotor, steam turbine rotor, large diesel engine crankshaft and so on.

5-axis CNC machining services

At DDPROTOTYPE, we specialize in rapid prototyping manufacturing & mass production over 20+ years, till of today we have 40+ senior engineers with range of technologies can provide professional solutions. 50+ kinds of surface finishing options, over 60+ certified materials in metal/plastic can cover different rapid prototyping needs. DDPROTOTYPE maintaining long term relations with world-class companies in various industries, such as medical device, Electronic consumer products, Automotive, Robotic, Aerospace etc. 7*24 hours one-on-one quickly respond, As fast as 3 days for delivery. Keep learn or contact us for getting instant quote.

DDPROTOTYPE is very familiar with 5-axis CNC machining services and has 4sets 5-axis CNC machining centers from JINGDIAO. Based on our many years experience,Following, let we talk about the mainly tips & application field of 5-Axis CNC machining.

5-Axis machining center of box-type parts

Box parts refer to the parts with more than one hole and multi-cavity. Such parts happened in sector as machinery, automotive, aircraft manufacturing and so on. For example, like engine crankcase, gearbox casing, headstock of lathe, spindle box, diesel engine block, and gear pump body and so on.
One time clamped on the auxiliary fixture, box-type parts are machined on the 5-Axis machining center can be completed around 60%-95% procedure contents, compare to 3-Axis & 4-Axis CNC machining center. The precision consistency of the part is good, quality is stable, the production cycle can be shortened and the cost can be reduced. For the part more machining stations and request worktable rotate the angle for several times, generally choose horizontal machining center to machining. When the machining stations not too much and the span is not large of the part, we can choose vertical machining center and start machining from one end.

5-Axis machining center of sculptured surface parts

Sculptured surface parts occupied a large proportion in aerospace, automotive, shipbuilding, military defense and so on, such as impeller, blade propeller, and variety of curve-surface cavity die, etc. When there is no machining interference area or blind area and as far as the machining possibility is concerned, the complex surface can be machined by using the ball end milling cutter and 3-Axis machining center, and the precision is high but the efficiency is low. If the work piece with machining interference area or blind area, it must take 4-Axis machining center, 5-Axis machining center into consideration for processing.

5-Axis machining center of irregular parts

Special–shaped parts are refer to irregular shape parts, most will request multi-stations mixes machining of point, line, surface, such as bracket, base, contour plate and so on. The rigidity of irregular shape parts is poor generally, and the deformation is out of control from clamping and cutting, the precision can’t be guaranteed also. At this time, we can use 5-Axis machining center to machining, adopt reasonable process, one time or twice clamping can complete multiple processes or all procedure contents.

5-Axis machining center milling plate parts and sleeve parts

Sleeve parts or shaft parts with key groove, radial hole, and end face distributed holes system and curved surface, as well as plate parts with much holes structure process, suitable for use 5-Axis machining center to do machining. Curved surface part distributed hole system on end face generally using vertical machining center, and using horizontal machining center to machining the parts with radial hole.

Features of 5-Axis machining center compared with ordinary machining centers

1.Suitable for the machiningof complex special-shaped parts

5-Axis CNC machining center can applied to machining the complex parts which hardly or basically cannot process by normal machining center, so it is widely used in aerospace, shipbuilding, mold and other machining industries.

2.High machiningprecision

5-Axis CNC machining center can do completed inspection for the size analysis of the material through five-axis positioning machining.

3.Stable and reliable machining

Realize computer control, eliminate human error, good machining consistency of the part, and stable quality.

4.High flexibility

When the machining object is changed, it is generally only necessary to change the numerical control sequence, which shows good adaptability and can save production preparation time. Basically, the 5-axis CNC machining center can form an automated production system with higher flexibility.

5.High productivity

The 5-axis CNC machining center has high machining accuracy, high rigidity and will automatically select the favorable machining amount. The productivity of the 5-axis machining center is high, which is around 3 to 5 times compare to ordinary machining center. It can cope with some complex parts’ machining, and production efficiency can be improved more than ten times or even dozens of times.

6.Good production conditions

The machine tool has a high level of automation, the operator’s work intensity is greatly reduced, and the working environment is better.

7.Conducive to management

The adoption of 5-axis machining center is conducive for computer control and production management, and creates conditions for the realization of the automation of the production process.

The 5-axis CNC machining center draw the attention from the world with its outstanding flexible automation performance, excellent and stable accuracy, agile and diversified functions, and has become a central technology in advanced production technology. On the other hand, through continuous research, the in-depth application of information technology has hurriedly advanced the further promotion of the 5-axis machining center. The 5-axis machining center is important basic equipment in the machine tool manufacturing industry, so its development has always attract people’s attention.

The post The Application Field of 5-Axis CNC Machining Center And Machiningtips appeared first on DDPROTOTYPE.

The Complete Guide For CNC Machining

Martin.mu — Fri, 31 May 2024 19:57:11 +0000

This paper introduces the complete guide of CNC machining in detail, including advantages and disadvantages, design rules and techniques, material selection, cost reduction, finishing service, etc., to help designers around the world to transform their ideas into ideal plastic or metal parts. AS a online cnc machining service shop,We believe ordering custom parts ought to be simple, fast, and straightforward. the concept of DDPROTOTYPE is to provide due contribution to the world’s manufacturing industry, committed to the prototype machining and Low-volume manufacturing of metals and plastics. We have 20 years of CNC machining experience, 3000 square meters of workshop, dozens of 3-axis and 5-axis CNC machines and ancillary equipment from Germany, the United States and Japan, such as EDM / WEDM machine from Japan and Hexagon CMM. Make sure that the designer’s whole energy is focused on product design. DDPROTOTYPE has already served 350 + customers in more than 50 countries around the world, including many of the world’s top 500 enterprises, such as Areva, Olympus, ABB, etc.Let DDPROTOTYPE become a part of your supply chain as Your Online CNC Machine Shop.

If you have any questions, please contact info@ddprototype.com.

What is CNC machining process?

CNC machining processes raw materials into final form by subtracting and removing materials. Drilling holes, channels or voids to make metal or plastic blanks into parts with different taper, diameter and shape. This is in sharp contrast to other types of processing (e.g. additive manufacturing), where materials are added and layered to produce parts of specified shape. This is also in contrast to injection molding, in which a mold is used to inject material in different material states and form shaped parts. CNC machining is widely used for various materials, including metals, plastics, wood, glass, foam and other composite materials. This versatility makes CNC machining a popular choice in the whole industry and enables designers and engineers to manufacture parts efficiently and precisely.

CNC machining operation follows four stages

Part design

Parts produced by CNC machining usually start with CAD software as the initial design. During the design phase, the engineer will carefully consider all aspects of the final product required, such as the parameters for optimizing performance, the working conditions of the final part, and the acceptable level of tolerance variation.

Design conversion

After the initial design phase, CAD models must be converted into functional CNC programs using computer aided manufacturing (CAM) software. CAM software can extract geometric requirements from original CAD model files and convert them into CNC compatible programming languages (such as G code or M code), which will determine the mechanical operation of the machine.

CNC machine tool preparation

Next, the CNC machine operator must set up the machine and materials according to the specifications required by the CNC program. The operator will ensure that the correct cutting or drilling tool is correctly installed and matched with the appropriate drill or end mill. The operator must also set up the workpiece, usually in a fixed fixture or directly mounted on a CNC machine tool.

Performing programmed operations

Finally, CNC machine operators perform the required mechanical processes. During operation, CNC program precisely controls the movement of the machine tool.

CNC machining advantages: timely, reliable, accurate and powerful

CNC milling and turning are highly accurate and repeatable processes. A tolerance of + / – 0.001 “– 0.005” can be achieved according to specifications. The machine can be programmed to run reliably 24 hours a week, 7 days a week if necessary, so CNC milling is one of the best ways to produce parts on demand. Using standard tools, CNC machining is particularly valuable for creating custom disposable parts, such as replacing old parts or providing customers with specialized upgrades. It can also be considered to expand the single piece production scale to more than 10000 units. Depending on the number, size and complexity of the equipment, the turnaround time for components can be as short as one day. Through transportation and delivery, the deadline can be met in a week.

Another major advantage of CNC machining technology is the achievable mechanical properties. All desirable mechanical properties of the selected metal or plastic can be retained by cutting the blank material instead of hot deforming it as in injection molding or additive manufacturing. CNC milling and turning can process more than 50 industrial grade metals, alloys and plastics. This selection includes aluminum, brass, bronze, titanium, stainless steel, peek, ABS and zinc. The only material requirement for CNC machining is that the parts have enough hardness for fixing and cutting. In order to obtain the most cost-effective CNC machining parts, it is suggested to expand the production capacity to disperse the cost of each part. When the number of CNC machining reaches dozens or hundreds, the unit price will gradually decrease. Structured mass production and transportation of CNC parts can help reduce waste or inventory costs.

Disadvantages: the cost of geometric complexity

One trade-off when using the high performance of CNC machining is that geometric complexity comes at a cost. Simple, bulky parts are the best design for CNC milling and turning. Although the degree of use of this tool is related to the number of shafts on the machine tool, there are always some design limitations due to the influence of the tool. In other words, the more axes you use, the more complex the function. Another trade-off is that the start-up cost of CNC processing may be high. There must be trained professionals to set up, load and program tools on CNC milling machines and lathes. Fortunately, this cost is fixed, so it will become more economical by using the same settings for multiple parts. Money can also be saved by repositioning parts to a minimum. Machining on shafts of 5 or more axes is sometimes more economical in polyhedral geometry because it does not require manual repositioning of parts.

CNC milling

In CNC milling, the parts are installed on the machine and the material is removed by using a rotary cutting tool. The following is an overview of the basic CNC milling process:First, the CAD model is transformed into a series of commands (g codes) that can be interpreted by CNC machine. This is usually done by the operator on the machine using the technical drawings provided.A piece of material (called a blank or workpiece) is then cut into a certain size and then placed on a built platform using a vise or directly mounted to the machine. Accurate positioning and alignment is the key to manufacturing accurate parts, for which special measuring tools are usually used.

Next, a special cutting tool is used to rotate at a very high speed (kilo RPM) to remove the material from the blank. It usually takes several passes to create a designed part. Firstly, the material is removed quickly with low precision to provide approximate geometry for the blank. One or more finishing passes are then used to produce the final part.If the model has features that cannot be achieved by the cutting tool in a single setting (for example, if the back side has slots), you need to flip the part and repeat the above steps.

After machining, parts need deburring. Deburring is a manual process to remove small defects left on sharp edges due to material deformation during machining (e.g., defects due to the drill bit being located far from the through hole). Next, if tolerances are specified in the technical drawings, the key dimensions are checked. The part can then be used or post processed.Most CNC milling systems have three linear degrees of freedom: X, y and Z axes. More advanced systems with five degrees of freedom also allow the bed and / or bit (A and B axes) to rotate. The 5-axis CNC system can produce parts with high geometric complexity and eliminate the need for a variety of machine tool settings.

CNC turning

In CNC turning, the parts are installed on the rotating chuck and the fixed cutting tools are used to remove the material. In this way, parts symmetrical along its central axis can be made. Turning parts are usually produced faster (and cheaper) than milling parts.
This is a summary of the steps to be followed in CNC turning :

Firstly, G code is generated from CAD model, and then cylinder with appropriate diameter is loaded into CNC machine tool.
The part begins to rotate at high speed, and the stationary cutting tool tracks its profile and gradually removes material until the geometry of the design is created. Holes along the central axis can also be made using a center drill and an internal cutting tool.
If the part needs to be flipped or moved, repeat the process. Otherwise, the parts can be cut from the stock and can be used or further post processed.

A typical CNC turning part is made by removing material from a cylindrical blank.

Generally, CNC turning systems (also known as lathes) are used to manufacture parts with cylindrical profiles. Non cylindrical parts can be manufactured using a modern multi axis CNC turning center equipped with CNC milling tools. These systems combine the high productivity of CNC turning with CNC milling functions, and can produce various geometries with rotational symmetry, such as camshaft and radial compressor impeller. In CNC turning operation, when the workpiece rotates at high speed on the spindle, the cutting tool remains stationary. CNC turning can rapidly produce cylindrical parts with strict tolerance. For example, ddprototype CNC lathes can produce parts up to 152 inches in diameter and 240 inches in length, while still maintaining a strict tolerance of ± 0.001 inches.

Because the boundary between milling and turning systems is fuzzy, the rest of this paper focuses on CNC milling, because it is a more common manufacturing process.

Types of CNC machine tools

The most common types of CNC machines are those that use cutting tools to remove excess material from the workpiece. Although CNC machines operate with water jet cutting and electrical discharge machining (EDM), this guide will focus on 3-axis and multi axis CNC machines.

3-axis CNC machine tool

3-axis CNC milling machines are very common because they can be used to produce the most common geometry. They are relatively easy to program and operate, so the start-up processing cost is relatively low. Tool access may be a design constraint in CNC milling. Since only three axes are available, some areas may not be accessible. If the workpiece only needs to be rotated once, this is not a big problem, but if it needs to be rotated many times, the labor and processing costs will increase rapidly. The 3-axis machine allows the cutting tool to move along straight three-dimensional vectors (up and down, left and right, forward and backward).

Multi axis CNC machine tool

Multi axis CNC machine tool is similar to 3-axis machine tool, but the degree of freedom of mechanical motion is higher. For example, multi axis machine tools can use rotary and diagonal cutting operations. There are three main types of multi axis CNC machine tools:

Indexing 5 axis CNC milling machine

Even if the milling machine can only cut along three linear axes during operation, the operator can still rotate the bed and cutter head for the next cutting between the two operations, thus improving the forming ability.

Continuous 5 axis CNC milling machine

This machine type allows continuous motion along three linear axes and two rotating axes during operation. This enables the operator to create highly complex tables from the target artifact.

The milling turning center

The milling turning center combines the functions of CNC lathe and CNC milling machine. The workpiece can be rotated at high speed or precisely positioned on the spindle for milling operation.

Of all the various machine configurations, the simplest setup is 3-axis CNC milling, which is usually the cheapest way to make simple parts with high tolerances. When cylindrical workpieces such as screws and couplings are required, CNC turning on a lathe is also a very cost competitive process. Generally, for similar parts, the cost of a lathe is 15% lower than that of a three axis machine tool.

When using 5-axis CNC machining, there are two options: indexing 5-axis CNC milling and continuous 5-axis CNC milling. In 5-axis CNC milling, the workpiece will rotate automatically, making it easier for the cutter to use the milling function. The two extra directions of motion are accomplished between the milling steps without removing the part from its fixture. The difference of continuous 5-axis CNC milling is that the machine can move in all directions at the same time when cutting the workpiece. Both processes eliminate the increased costs and potential human errors associated with manually repositioning the workpiece. Because of these advantages, five axis machining is the best solution for complex parts. Compared with the “basic” 3-axis CNC milling machine, the cost of 5-axis machining is increased, and the indexing 5-axis CNC milling machine is the cheaper of the two. The cost of continuous 5-axis CNC milling is usually more than 20% higher than that of indexing 5-axis machine tool, which is about twice the cost of standard 3-axis milling.

Design CNC machining parts – CAD model design

The concept of CAD is machining point. In addition to the design requirements directly related to the final application of the product, the engineer must also pay attention to the functions and limitations of the CNC machine tools to be used for actual cutting operations. Engineers must convert the original CAD model file to a CNC compatible format, such as open source step or IGES format, or to a more restricted format, such as IPT or sat. It is also a best practice for engineers to create technical drawings that will be sent with digital CAD instructions. These drawings are used to verify design tolerances and geometry. Help the machinist identify the salient features of the part; and act as the actual source of validation when problems arise.

Seven rules of CNC machining process

Rule 1: all roads lead to radius

Since most drills are cylindrical in design, this means that any internal cuts you make will also produce curved corners / edges, also known as rounded corners. When designing parts with internal fillet, follow the principle of “bigger is better”. The resulting angle will be half the diameter of the tool used.

Use a non-standard radius, such as 1.25 mm instead of 1 mm, to allow a certain tool clearance to cut corners. Where possible, different wall and floor radii should also be used for design so that the same tool can be used throughout the process.

The precise measurement of the inner corner will be related to the depth of the cavity being machined. When inserting inner corners and edges, the radius should be greater than one third of the cavity depth.

Rule 2: right angle undercut

To create right angles in CNC machined parts, it is better to add undercuts to the design rather than try to reduce the radius of corners to achieve similar results. To avoid the additional cost of custom tools, design undercut slots of standard size, i.e. 3 mm to 40 mm wide in millimeters. Due to the shape of the tool used, undercut should be as shallow as possible. The maximum depth that the undercut tool can reach will be twice the width of the tool head.

Rule 3: fillets can cause cavities

The cavity / cavity depth is usually related to the diameter of the tool used to make the inner fillet. As a guide, the groove depth should be up to 3-4 times the tool diameter. If the depth exceeds 6 times the tool diameter, a larger tool is required. This will sacrifice your corner radius. The cavity width should also be considered when machining the cavity. It is best to keep the depth at 4 times the width, which is a good guide.

Rule 4: tall features, bad vibrations

As with the depth of cavity and pit, the maximum height of tall feature is 4 times of feature width at most. The higher the feature is, the easier it is to vibrate, thus reducing the machining accuracy of parts.

Rule 5: avoid thin walls

Generally speaking, it is better to use thicker walls in part design. As with high walls, vibration increases when thin-walled features are made. Heat must also be considered when processing plastics. Due to the friction of the cutter head, the thinner wall will be easier to soften and warp. As a guide, the minimum thickness of the plastic wall should be between 1.0 and 1.5 mm. The minimum wall thickness in metal parts may be between 0.5 mm and 0.8 mm. If walls are supported, they should be thicker or higher to avoid vibration and tremor.

Rule 6: follow the standard when drilling

There are two kinds of holes to choose in CNC milling: blind hole and through-hole. Regardless of the type selected, the recommended depth and diameter are the same. The hole diameter should be related to the standard bit size of 25.5 mm (diameter over 1 mm) and above. The nominal depth of the hole depends on the maximum diameter of the hole. Typically, the depth of the hole is created equal to 10 times the nominal diameter of the hole.

Rule 7: compliance with thread standards

It is also important to maintain the standard size when creating threads. The larger the thread, the easier the processing. The maximum length should be maintained to 3 times the nominal diameter of the hole. Additional costs are avoided by retaining the ready-made thread size in the part.

CNC material selection guidelines

Proper material selection is essential for CNC machining operations. The choice depends largely on the intended use of the end product. As a subtractive manufacturing process, CNC machining uses raw materials such as metals or plastics to make parts. This block is called a material blank. No matter which material is used, it is very important to select the correct blank size before the production process. In general, it is advisable to select a blank with each size at least 0.125 inch (~ 0.3 cm) larger than the final part size to resolve any inconsistency in the raw material. At the same time, it is important not to use too large blanks to minimize material waste. Another important thing to remember before ordering CNC machined parts is that the choice of materials affects production time and cost. This is because some materials are Machinable better than others, which means they are easier to process. Faster processing speeds eventually translate into lower production costs.

Metals are mainly used in applications requiring high strength, hardness and heat resistance. Plastics are lightweight materials with a wide range of physical properties, which are usually used because of their chemical resistance and electrical insulation properties. Material properties of interest are mechanical strength (expressed as tensile yield strength), machinability (machinability affects CNC pricing), material cost, hardness (mainly for metals) and temperature resistance (mainly for plastics).

You need to examine a range of material properties to determine which material is most suitable for your design, such as:

tensile strength
hardness
It is easy to operate
Chemical resistance
Corrosion resistance
Thermal performance

metal parts

Generally, high ductility metals are easier to process because CNC milling cutters can cut metal more easily and achieve higher efficiency. For example, brass is one of the easiest metals to process because of its good ductility. Aluminum alloy is also very suitable for CNC machining, so it can shorten the production time. Steel, on the other hand, is a solid metal with much lower machinability than aluminum, which means lower productivity and higher costs. However, it is important to remember that different grades of steel have different levels of workability, depending on their carbon content. Steels with very low and very high carbon content are usually difficult to machine. For example, stainless steel 304 with a low carbon content is difficult to machine because it becomes sticky and hardens too quickly. Additives such as sulfur and phosphorus make stainless steel easier to process, such as stainless steel 303. From a machining point of view, carbon steel usually takes four times as long as aluminum, while stainless steel takes twice as long.

Plastic parts

Although thermoplastic plastics can be machined, the material properties of polymers may pose challenges to CNC machining. Firstly, due to the poor thermal conductivity, many thermoplastic plastics will melt or warp when contacting with CNC milling cutter or drill bit. For parts that do not require metal strength and stiffness, thermoplastic offers a cheaper option. In the range of thermoplastic, Delrin (POM), high density polyethylene (HDPE) and ABS have good machinability. Although peek, ULTEM, nylon and many composites are popular for their strength and durability, they are more difficult to process.

Aluminum alloy

Aluminum alloy has excellent strength / weight ratio, high thermal conductivity and conductivity, and natural corrosion resistance. They are easy to process and low in batch cost, so they are often the most economical option for creating custom metal parts and prototypes.Aluminum alloys usually have lower strength and hardness than steel, but can be anodized to form a hard protective layer on its surface.

Aluminum alloy 6061 has the most excellent cutting strength than other aluminum alloy.
Aluminum 6082 composition and material properties are similar to those of 6061. It meets European standards and is therefore more commonly used in Europe.
Aluminum 7075 is the most commonly used alloy in aerospace applications because it has excellent fatigue properties for steel and can be heat treated to achieve high strength and hardness, so it is essential to reduce weight.
Aluminum 5083 has higher strength and excellent seawater resistance than most other CNC aluminum machining and is therefore commonly used in architectural and marine applications. It’s also a great choice for welding.

Material properties:

Typical density of aluminum alloy: 2.65-2.80 g / cm3
It can be anodized
Nonmagnetic

stainless steel

Stainless steel alloys have high strength, high ductility, excellent wear resistance and corrosion resistance, and are easy to weld, machine and polish. Depending on their composition, they can be (basically) nonmagnetic or magnetic.

Stainless steel 304 is the most common stainless steel alloy with excellent mechanical properties and good machinability. It is resistant to most environmental conditions and corrosive media.
Stainless steel 316 is another common stainless steel alloy with mechanical properties similar to 304. Although it has higher corrosion and chemical resistance, especially for salt solutions (e.g. seawater), it is usually preferred for use in harsh environments.
Stainless steel 2205 duplex stainless steel is the highest strength stainless steel alloy (twice of other common stainless steel alloy), and has excellent corrosion resistance. It is used in harsh environments and has many applications in the oil and gas industry.
Stainless steel 303 has excellent toughness, but has lower corrosion resistance than 304. Due to its excellent machinability, it is often used in mass applications such as nuts and bolts for aerospace applications.
The mechanical properties of 17-4 stainless steel (SAE 630 grade) are comparable to 304. It can be precipitation hardened to a very high degree (compared to tool steel) and has excellent chemical resistance, making it suitable for very high performance applications, such as the manufacture of turbine blades.

Material properties:

Typical density: 7.7-8.0 g / cm3
Non magnetic stainless steel alloy: 304, 316, 303
Electromagnetic stainless steel alloy: 2205 duplex, 17-4

Low carbon steel {mild steel}

Low carbon steel, also known as low carbon steel, has good mechanical properties, good machinability and good weldability. Because of their low cost, they can be used for general purposes, including the manufacture of mechanical parts, fixtures and fixtures. Low carbon steel is susceptible to corrosion and chemical attack.

Low carbon steel 1018 is a general alloy with good machinability and weldability, as well as excellent toughness, strength and hardness. It is the most commonly used low carbon steel alloy.
Low carbon steel 1045 is a medium carbon steel with good weldability, good machinability, high strength and impact resistance.
Low carbon steel A36 is a common structural steel with good weldability. It is suitable for various industrial and architectural applications.

Material properties:

Typical density: 7.8-7.9 g / cm3
magnetic

Alloy steel

Alloy steels contain other alloying elements in addition to carbon, thus improving hardness, toughness, fatigue and wear resistance. Similar to low carbon steel, alloy steel is also susceptible to chemical corrosion and corrosion.

Alloy steel 4140 has good overall mechanical properties, as well as good strength and toughness. This alloy is suitable for many industrial applications, but is not recommended for welding.
Alloy steel 4340 can be heat treated to achieve high strength and hardness while maintaining good toughness, wear resistance and fatigue strength. This alloy is weldable.

Material properties:

Typical density: 7.8-7.9 g / cm3

Magnetic

Tool steel

Tool steel is a kind of metal alloy with high hardness, rigidity, wear resistance and heat resistance. They are used to create manufacturing tools (hence the name), such as molds, dies and molds. In order to obtain good mechanical properties, it must be heat treated.

Tool steel D2 is a kind of wear-resistant alloy, its hardness can be maintained at 425 ° C. It is usually used to make cutting tools and dies.
Tool steel A2 is a kind of air hardening general tool steel, which has good toughness and excellent dimensional stability at high temperature. It is usually used to make injection moulds.
Tool steel O1 is an oil hardening alloy with high hardness of 65 HRC. Commonly used for cutting tools and cutting tools.

Material properties:

Typical density: 7.8 g / cm3

Typical hardness: 45-65 HRC

Brass

Brass is a metal alloy with good machinability and excellent conductivity, which is very suitable for applications requiring low friction. It is also often used in architecture to produce parts with a golden appearance for aesthetic purposes.

Brass c36000 is a kind of material with high tensile strength and natural corrosion resistance. It is one of the easiest materials to process, so it is often used in mass applications.

Material properties:

Typical density: 8.4-8.7 g / cm3

Nonmagnetic

ABS

ABS is one of the most common thermoplastic materials with good mechanical properties, excellent impact strength, high heat resistance and good machinability.
The low density of ABS makes it very suitable for lightweight applications. ABS parts machined by CNC are usually used as prototypes before mass production by injection molding.
Material properties:
Typical density: 1.00-1.05 g / cm3

Nylon

Nylon, also known as polyamide (PA), is a kind of thermoplastic, which is widely used in engineering applications due to its excellent mechanical properties, good impact strength, high chemical resistance and wear resistance. Although it is easy to absorb and absorb moisture.

Nylon 6 and nylon 66 are the most commonly used grades in CNC machining.

Material properties:

Typical density: 1.14 g / cm3

Polycarbonate fiber

Polycarbonate is a thermoplastic with high toughness, good machinability and excellent impact strength (better than ABS). It can be colored, but it is usually optically transparent, so it is very suitable for a wide range of applications including fluid equipment or automotive glass.

Material properties:

Typical density: 1.20-1.22 g / cm3

POM（Delrin）

POM, whose commercial name is Delrin, is known as an engineering thermoplastic with the highest processability among plastics.

POM (Delrin) is usually the best choice when CNC machining plastic parts with high precision, high stiffness, low friction, excellent dimensional stability at high temperature and very low water absorption.

Material properties:

Typical density: 1.40-1.42 g / cm3

PTFE (Teflon)

PTFE, commonly known as Teflon, is an engineering thermoplastic with excellent chemical and heat resistance and the lowest coefficient of friction in any known solid.

PTFE (polytetrafluoroethylene) is one of the few plastics that can withstand temperatures above 200 OC and is an excellent electrical insulator. However, it has pure mechanical properties and is usually used as a lining or insert in an assembly.

Material properties:

Typical density: 2.2 g / cm3

High density polyethylene

High density polyethylene (HDPE) is a kind of thermoplastic with high strength to weight ratio, high impact strength and good weather resistance.

HDPE is a lightweight thermoplastic, suitable for outdoor use and pipeline transportation. Like ABS, it is often used to create prototypes before injection molding.

Material properties:

Typical density: 0.93-0.97 g / cm3

PEEK

Peek is a high performance engineering thermoplastic with excellent mechanical properties, thermal stability over a wide temperature range and excellent resistance to most chemicals.

Peek is often used to replace metal parts because of its high weight to weight ratio. It also provides a medical level that makes peek suitable for biomedical applications.

Material properties:
Typical density: 1.32 g / cm3

Rule summary

Aluminum 6061 is the most common CNC machining material with the lowest cost.
Due to its excellent processability, POM (Delrin) is the most economical CNC plastic.
Select a metal alloy for applications requiring high strength, hardness and / or heat resistance.
Choose plastics with special material requirements for lightweight applications or pre-injection prototypes.

Application range of various materials

Aluminum

Key performance: aluminum is highly valued for its strength to weight ratio and corrosion resistance. It also has good thermal conductivity and conductivity.

Aluminum 6061-t6:6061 is one of the most commonly used aluminum varieties and has been widely used. The T6 mark gives the material an ultimate tensile strength of 276 MPa. Common application: General
Aluminum 7075: ultimate tensile strength is 572 MPa, comparable to steel. Useful for high stress applications, its use is limited by high costs. Common applications: aerospace, automobile, ship
Aluminum 2024-T3: 2024-T3 2000 series alloy has high strength weight ratio, tensile strength is 400-430 MPa, yield strength is at least 270-280 MPa. T3 certification, solution heat treatment and cold working have been carried out. Common applications: industrial, aerospace, medical, electronic products.
Aluminum 5052: at 117 MPa, the fatigue strength of this kind of aluminum alloy is higher than that of most aluminum alloys. It also has excellent seawater and salt spray resistance. Common applications: ship, aerospace, electronics.
Aluminum mic-6: similar to 7000 series aluminum alloy, mic-6 is a cast plate material commonly used in mold and substrate. Common applications: aerospace, electronics, gear.

Brass, bronze and copper

Key features: pure copper is a soft and malleable metal with high thermal and electrical conductivity. Brass and bronze are alloys of copper. Brass is a mixture of copper and zinc, and bronze is mainly copper and tin. In general, brass is valued for its machinability and high strength retention. Bronze has low friction performance and high corrosion resistance. Brass, bronze and copper are usually chosen for aesthetic purposes.

C360 brass: C360 is a highly machinable material with the lowest cost of all brass alloys. Industry: industry, business.
Brass 260: the most malleable brass alloy 260 is used more than other similar products. Industry: industry, commerce.
C932 M07 bearing bronze: for light duty applications, this alloy is easy to process and corrosion resistant. Industry: general.
ETP copper C110: this alloy has the highest electrical conductivity (100% IACS) of all metals except silver (105% IACS). Industry: power, construction, medical.
Copper 101: base material for many brass and bronze, copper 101 has high ductility (elongation 5% to 50%) and impact strength. Industry: electronics, automobile.

Steel

Key features: can be said to provide the widest range of CNC machining materials, steel has stainless steel, alloy, tools and low carbon steel options. In general, steel has good mechanical properties and is easy to process.

Steel 1018: this low carbon general purpose steel is ductile and suitable for forming and welding. Industry: general, gear, screw, nut.
ASTM A36: an example of low carbon steel, A36 is a low-cost alloy with good mechanical properties, including ultimate tensile strength of 400-550 MPa and elongation at break of 20%. Industry: gear, construction.
Alloy steel 4130: this multifunctional steel alloy is optimized in terms of composition (strength limit (670 MPa), toughness (yield strength 435 MPa), and machinability). Industry: aerospace, oil and gas, automotive.
Stainless steel 304: the most common stainless steel variety and representative of the basic quality of steel, the alloy has higher corrosion resistance and lower conductivity than most other steels. It is not suitable for applications requiring welding. Industry: food, screw, automobile.
Stainless steel 17-4: this precipitation hardening stainless steel is known for its high strength and mechanical properties and can be further developed by heat treatment. It has good mechanical properties even at 600 degrees Fahrenheit, and has high corrosion resistance. This material can work well in harsh environments. Industry: nuclear, marine, food and medical.

Titanium

Key features: Although titanium is heavier than aluminum (but still lighter than steel), titanium is also known for its excellent weight to strength ratio. Due to their hardness, many titanium varieties are considered difficult to process.

Titanium grade 2: Grade 2 is a common form of this metal with high strength (limit 344 MPa) and excellent corrosion resistance. It is usually used to make heat exchangers. Industry: aerospace, automotive, chemical.

Titanium 6Al-4V: another commonly used titanium variety, this alloy is the best choice when low density (4.429 – 4.512 g / cm3) and excellent corrosion resistance are required. Industry: medical, aerospace, marine, natural gas.

Zinc alloy

Key feature: zinc is not commonly used in CNC machining because most varieties are too brittle for processing. In some specific forms, the material becomes easy to process and easy to handle.

Zinc alloy plate 500: a continuously cast alloy with Machinable zinc having good electrical conductivity and high corrosion resistance. Industry: architecture.

Plastic Material

Key features: lightweight and rugged, some industrial plastics can be considered as low-cost alternatives to metal parts. Plastics are widely used in all industries.

Abs: this common high-strength thermoplastic with electrical insulation is ideal for low-cost, lightweight molds and prototypes. Industry: general, medical, automotive, electronics.
Acetal: Delrin is the easiest plastic to process. It has excellent stiffness (bending strength 82.7 MPa), low friction and good moisture resistance. Industry: general, gear, electronics, medical, construction.
Nylon 6 / 6: common polyamide, nylon 6 / 6 (or 66 for short) has high mechanical strength (66 MPa), stiffness and stability under thermal and chemical action. Industry: automobile, electronics, gear, pipe.
Peek: this advanced thermoplastic can be used in all kinds of occasions with high mechanical requirements. Industry: medical, aerospace, automotive, electronics.
Polycarbonate: commonly known as PC, this transparent plastic has excellent optical properties. It’s rugged, lightweight and rugged with high impact resistance (600 – 850 J / M). Industry: general, electronics, aviation, automobile, pipeline.

Finishing services

Finishing service after machined can change the appearance, surface roughness, hardness and chemical resistance of the parts produced. The following is a brief overview of the most common surface treatments for CNC machining.

Machined

The machined parts have the most stringent tolerances because no additional work is required on them. However, the marking along the cutting tool path is visible. The standard surface roughness of machined parts is 3.2 μ m (125 μ in), which can be reduced to 0.4 μ m (16 μ in) by further operation.

The most stringent dimensional tolerance.
No additional cost (standard surface treatment).

Bead blasting

Bead blasting adds a uniform matte or satin finish to the machined parts, eliminating all tool marks.

Bead blasting is mainly used for aesthetic purposes because the surface roughness obtained cannot be guaranteed. Key surfaces or features such as holes can be masked to avoid dimensional changes.

A pleasing matte or satin finish.
Low cost surface treatment.
Provide different roughness.

Anodizing (transparent or colored)

Anodizing adds a thin and hard non-conductive ceramic coating on the surface of aluminum parts to improve their corrosion resistance and wear resistance.

Critical areas can be masked to maintain strict tolerances. Anodized parts can be dyed to produce a smooth, beautiful surface.

Durable, beautiful appearance.
Can be applied to the lumen.
Can be colored to any Pantone hue.

Hard coating anodizing

Anodizing of hard coatings produces thick, high-density ceramic coatings that provide excellent corrosion and wear resistance.

Hard coating anodizing is suitable for functional applications. A typical coating thickness of 50 μ m is not normally applied. Critical areas can be masked to maintain strict tolerances.

High wear resistant coating for high-end engineering applications.
Can be applied to the lumen.
Good dimensional control.

powder coating

Powder coating adds a layer of strong, wear-resistant and corrosion-resistant protective polymer coating on the surface of parts.

It can be applied to parts of any material and has a variety of colors to choose from.

Robust, wear-resistant and corrosive coatings for functional applications.
It has higher impact resistance than anodizing.
Compatible with all metal materials.

Silk screen printing

Screen printing is a cheap way to print text or logo on the surface of CNC machining parts for aesthetic purposes.

It can be used in addition to other finishes such as anodizing. Only the printed content can be applied to the outer surface of the part.

Print custom text or logo at low cost.
Available in a variety of colors.

Tips for reducing the budget of your CNC project

The cost of CNC machining parts depends on the following factors:
Processing time and model complexity: the more complex the geometry of the part, the longer the processing time and the higher the cost.
Start up costs: These are related to CAD file preparation and process planning, but the cost is basically fixed. There are opportunities to reduce unit prices through economies of scale.
Material cost and surface treatment: the cost of bulk materials and the ease of processing of materials greatly affect the total cost.

Let’s sum up

The 3-axis CNC milling machine can make parts with relatively simple geometry at low cost and have excellent accuracy.
The unit cost of CNC lathe is the lowest, but it is only suitable for parts with rotational symmetry.
The parts made by 5-axis CNC milling machine with index have the characteristics that they can’t align with one of the main shafts quickly and have high precision.
The parts manufactured by continuous 5-axis CNC milling machine have highly complex “organic” geometry and smooth contour, but the cost is high.
Milling CNC center combines the advantages of CNC turning and CNC milling into one system to manufacture complex parts at lower cost than other 5-axis CNC systems.

CNC machining parts are widely used in all walks of life. At ddprototype, we serve a wide range of areas, including:

medical care
automobile
Bicycle
robot
Aerospace
ship
agricultural machinery
electronic product
Camera and other precision manufacturing parts of all walks of life

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