Comparison of aluminum mold and steel mold

Comparison of aluminum mold and steel mold

General speaking about the injection mold is a steel mold. But its machining cost is expensive and the lead time is long. If only small volume or medium volume parts are required for manufacturing, aluminum molds have become the first choice. As we all know, aluminum is a very popular material in the prototypes field. DDPROTOTYPE is one of the leaders of rapid prototyping and injection molding in China. According to statistics, 70% prototype’s material processed by CNC is aluminum. As technology advanced continuously, aluminum has also become a popular choice for mass production. What is the difference between aluminum mold and steel mold? This article will introduce the difference between the two in details.

Steel Mold

Steel molds are suitable for mass production. For mass production and multi-batch production of plastic parts, steel mold is your best choice. A high upfront investment, and proper maintenance, it can last reliably for many years. Steel is stronger than other materials during longer production runs.

Steel Mold

Applicable to a variety of resin materials. While both steel and aluminum are generally suitable for a variety of standard injection molding resins, if you are working with more complex formulations (such as those reinforced with glass, fibers, or other additives), then Steel mold has more advantages. While relatively soft metals, such as aluminum, they are a greater risk of scratches or other damage due to certain types of additives, which can affect the finish and texture of the final part. Make sure to check the compatibility of the selected resin, especially if it contains additives.

Applicable to a variety of resin materials.

Suitable for multi-feature plastic parts. When a part requires very high feature capabilities (for example, thin, uneven walls, smaller fillets, and narrower cavity areas), steel molds often provide a better results than aluminum’s. The strength and hardness of steel means it is better to hold the shape of those extremely precise areas.

multi-feature plastic parts

Durability. The main advantage of steel molds is that they are far more durable than any other available material. If long production runs are expected and the mold is intended to be reused for many years, steel is the best choice for the mold. The high up-front investment requires more than just a return on reuse and the tens of millions of parts the tooling is capable of producing.

mass production injection moulding

There are many factors to consider when making molds, among which the drive to reduce costs affects every part of the production process, so it is very important for manufacturers to find a material that not only meets the parameters but also a competitive price. Aluminum alloy molds have many advantages over steel and other materials in the field of mold making due to their versatility, adaptability and low cost.

Aluminum Mold

Manufacturing cost. The raw cost of making an injection mold, speaking to the price, aluminum has a clear advantage over steel. Of course, the total value and return on investment of aluminum and steel molds can vary greatly depending on how the mold is used (e.g., expected production lifespan). However, all other factors being equal, the initial investment in aluminium will be a lot less than the investment in steel, or even a fifth of the price.

Aluminum Mold

Individual part cost. This factor depends on your expected production volume and the overall lifespan of the injection mold. For shorter run times, the lower upfront cost of aluminum molds can reduce the overall cost per part. If you plan to use the mold for mass production of thousands of parts, you will find that the investment in steel mold pays off. Also, as the service life increases, the cost of the parts decreases.

plunkett prototype

Aluminum molds are suitable for small volume production. As mentioned above, due to the lower up-front cost of aluminum molds, aluminum molds can provide higher value for small volume production, especially for small and medium small volume, such as 2000-5000 PCS parts.

low volume manufacturing

Heating and cooling times. Compared with steel molds, aluminum molds conduct heat more efficiently, so they heat and cool speed is much faster than steel molds, often up to 7 times. In particular, cooling time accounts for a large portion of the total cycle time of injection molding. Therefore, choosing aluminum molds at the right time can greatly reduce cycle time, which is also one of the important factors affecting cost.

The shrinkage, warpage, and etc defects. Aluminum has excellent heat dissipation properties, which means molds are better and fast to achieve uniform heating and cooling times. This has advantages in reducing the number of defective and scrapped parts. Uneven heating and cooling is a significant factor in defects such as sink marks, voids and burn marks. Aluminium molds can offer better cost advantage due to the lower scrap rate of parts.

warpage injection molding

Easy to modify and repair. Damaged or deformed steel molds can be very difficult and expensive to repair due to the extremely high hardness of the material. In this case, a new mold will usually be required. Here’s the obvious comparison. Aluminum molds are easier to repair and, as a softer material, they are easier to modify in the event of a possible error.


  • Aluminum molds are faster and cheaper to manufacture, and are suitable for rapid production in small volume production.

  • Traditional steel molds are often capable of producing millions of parts, however, making molds usually takes months and costs more, but it has better wear resistance than aluminum mold.

  • If you need to produce parts on demand within a few days, and if you want to avoid risky investments until the part design is truly validated, then using an aluminum mold may be a good choice.

DDPROTOTYPE is a one-stop service solution provider for precision injection mold design, manufacturing, and production. It has been deeply rooted in the mold industry for more than 20 years, specializing in more high-tech mold manufacturing technology, and has successfully obtained a number of patents. If you have any needs about injection molding technology, please visit, we are happy to share our experience in plastic injection molding with you and provide you with economical plastic injection molding solutions.