You should know the information about CNC machining Delrin

You should know the information about CNC machining Delrin

From cars to musical instruments and even kitchens, Delrin is always around us. It is a high-strength, high-toughness, low-friction, dimensionally stable thermoplastic. And it has good machinability. Enables the manufacture of various parts or prototypes with precise dimensions.

CNC - machining-delrin

What is Delrin?

polyformaldehyde (POM) is a semi-crystalline engineering plastic, its most well-known brand name is Delrin, produced by the famous American DuPont. Other brands are Kocetal, Ultraform and Celcon. Delrin has a density of 1.410–1.420 g/cm3, maintains good properties and good colorability from -40°C to 120°C, and has a melting point of 175°C

At a glance


Lead Time






CNC Milling

CNC Turning

As fast as 3 days

Following drawing:

as low as +/- 0.005 mm

No drawing: ISO 2768 medium


High rigidity and strength applications like gears, bushings, and fixtures

150, AF (13% PTFE Filled), 30% Glass Filled

White, black, brown

delrin acetal plastic

Delrin has profiles in many forms, such as sheet, bar, tube, etc., suitable for CNC milling and CNC turning, as well as laser cutting. Granular Delrin is suitable for injection molding and plastic extrusion processes. Delrin enables thinner, lighter parts or prototyping, and it can reduce production costs. In addition to the standard Delrin, there are two types of Delrin AF (13% PTFE filled) and Glass-Filled Delrin.

  • Delrin AF. Delrin AF has a more excellent coefficient of friction, wear resistance, toughness and dimensional stability, and it is manufactured in many lubricated load-bearing parts,such as bushings, bearings, cams, thrust washers, washers and valve seats.

  • Glass-Filled Delrin. Glass-Filled Delrin has excellent rigidity and dimensional stability, creep resistance, impact resistance and fatigue resistance, and is commonly used in automotive door systems, construction fields, clamps, gears, etc.

Delrin Properties


Tensile Strength

Elongation at Break



Maximum Temp

McMaster Part Number

Delrin 150

9,000 PSI


Rockwell M90

1.41 g/㎤
0.05 lbs / cu. in.

180° F


Delrin AF (13% PTFE Filled)

8000 psi


Rockwell R115-R118

1.41 g/㎤
0.05 lbs / cu. in.

185° F


Delrin (30% Glass Filled)

7700 psi


Rockwell M87

1.41 g/㎤
0.05 lbs / cu. in.

185° F


Material properties requested by DDPROTOTYPE from Delrin material suppliers

Advantages and Limitations of CNC Machining Delrin

Due to its mechanical properties and machinability, Delrin is very suitable for CNC machining. Its main advantages are as following:

Low moisture absorption and chemical resistance:

Delrin maintains excellent mechanical properties in wet environments and is naturally resistant to corrosive materials such as hydrocarbons, solvents and neutral chemicals.

Good wear resistance:

Delrin parts’ or prototype’s surfaces are very hard and resilient, with a low coefficient of friction, it is the preferred plastic material for wear-resistant parts.


Delrin is easier to cut and its excellent dimensional stability allows the manufacture of tight tolerance plastic parts or prototypes.

High strength, toughness and impact resistance:

Delrin is a tough, high-strength material that makes parts suitable for working in harsh environments.

Creep resistance:

Delrin’s creep and fatigue resistance make it ideal for manufacturing long-life parts.

Electrical Insulator:

Delrin is electrically insulating and is a suitable material for manufacturing electronics.

Natural Lubricity:

A prominent advantage of Delrin is natural lubricity, which makes it ideal for manufacturing gears, bearings, etc.


Delrin’s tensile strength and impact resistance are comparable to some metals, but Delrin is much lighter.

Machining Limitations of Delrin

Although Delrin has many advantages, it also has some limitations and is not suitable for manufacturing all parts.


Chemical resistance is a double-edged sword, and the adhesive seems to have a limited effect on Delrin, making it difficult to bond.


Delrin doesn’t stop burning unless it burns out of oxygen, and requires a Class A fire extinguisher.

Thermal Sensitivity:

Above a certain temperature, such as above 120 degrees, Delrin is easy to deform and is not suitable for working at excessively high temperatures.

CNC machining supplier

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CNC Machinist

Applications of CNC Machining Delrin

Common applications of machining Delrin include:

  • Mechanical components include gears, pumps, valves, screws, housings, springs, impellers, valves, bearings, bushings, etc.

  • Electronic applications include insulators, connectors, shafts, connectors, and consumer electronics components.

  • Automotive components include door lock systems, hinged housings and fuel transmitter units, etc.

  • Medical components include inhalers, insulin pens, and medical devices.

  • Furniture components such as handles, locks, hinges, etc.


CNC Machining Delrin Tips

Although Delrin is relatively easy to process, strict precautions must be followed. Precautions during design or machining include:

Design Advice

Min Wall Thickness

Min End Mill Size

Min Drill Size

Max Part Size


Radii : Depth

0.5 mm

0.8 mm (0.03 in)

0.5 mm (0.02 in)

1200 x 500 x 152 mm (milling)

152 x 394 mm (turning)

Dovetail Profiles.

Full Radius.

Square Profile.

Depth must not exceed 12x drill bit diameter.

For end mills,Depth must not exceed 10x tool diameter.

  • Design: Keep the wall thickness as consistent as possible, preferably over 5mm. Delrin parts with larger dimensions may warp more easily during machining.

  • Coolant: Delrin will deform whentemperatures above 120°C, so in the CNC machining process, it is necessary to choose a suitable coolant to keep it cool, such as air coolant, and it can also smoothly remove chips.

  • Dedicated cutter: When machining Delrin, it is best to use a dedicated tool, avoid mixing withaluminum’s cutters or other metals’ cutters, and be sure to keep the tools clean and sharp.

  • Clamping Fixture: During CNC machining, use a slight clamping force to avoid pinching the workpiece.

  • Reaming: When using a fixed reamer, remove at least 0.15mm during final reaming to prevent undercutting.

  • Threading/Tapping: Delrin is a flexible plastic, the finish should be no less than 0.15mm, such as 0.15 to 0.25mm, and continuous cutting is required.


After a lot of practice, it is proved that Delrin is a substitute for some metals and has been widely used in various fields. As a trusted prototype manufacturer in China to provide the perfect solution for CNC machining Delrin. “If you have any CNC project please feel free to send CAD files to DDPROTOTYPE, we will provide design advice for free, reduce costs and provide precision parts,” says Martin, the principal of DDPROTOTYPE. 

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