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Aluminum vs. Steel Tooling Injection Molding

How to build a proper tool is critical for a new project. We always looking for the right material to produce the right products from time to time. What if production demands required for smaller quantities? Aluminum tool for low-volume production that runs only a thousand parts or even less is your first choice. In certain cases, aluminum tools may be a better choice than steel tools. It is cost-effective and shorter manufacturing lead time to process. However, Aluminum tools always easy to wear out quickly, so it’s not recommended for higher-volume production. High volume or precision and accuracy parts required a steel tool that can keep longer tooling life even up to 1,000,000 parts. Also, it is can be maintained or replace some of the components to extend their lifetime during serial production. However, steel tools are more expensive and longer manufacturing lead time than Aluminum tools. For product development teams, choosing the right material for their tools is just as important as choosing the right material for the whole project. An exact tool made from the right material makes for a smooth manufacturing process.

How many parts will be consumed during the entire project and what is the manufacture lead time? Engineers will consider these questions before the project launch. Mold suppliers will choose the right material that satisfies the maximum quantity with the lowest cost according to the specific qualities per designer’s requirement. It is quite common to choose different mold materials according to actual project specifications. They both have different advantages and disadvantages to the injection molding process. Here is a quick look at the differences between steel and aluminum tooling.

The Advantage and Disadvantage of an Aluminum Injection Mold


Aluminum tooling is very suitable for low-volume production prototype runs, providing a cost-effective solution, with a shorter lead-time than steel tooling. For aluminum tooling, we can typically be 30-50% cheaper than steel tooling, with a 40-60% reduction in lead-time compared to steel tool.

To achieve a shorter lead time, aluminum tooling services are the only way you can deliver this essential for your business. Technology and advanced manufacturing methods have driven the cost-effective method of testing new designs and delivering final products.

Aluminum tooling also provides engineers more options than steel when it comes to manufacturing. As we know, steel mold modification or repair will cause extra cost because of material is strong, some of the modification even need to be welding on a tool which will have affected on surface finish. So for most of the bigger design changes, engineers will have to rebuild a new mold. Aluminum is softer and easier to repair, plus its excellent heat dissipation can reduce the number of parts rejection rate due to cosmetic defective such as shrink, warp, and sink marks.

Aluminum tooling does have its disadvantage. Such as, Aluminum is not as durable as steel and molds easy to wear out after a few thousand production cycles. This can cause nonconformities in the part, molders must be very careful to check the quality of the production parts after molding a few thousand parts. Another weakness to note is that, if tooling with aluminum, the surface finish may be poor and not easy to process texture or polish due to the material’s low density. Tolerances are also wider than steel tool so it won’t fit for the precision parts.

The Advantage and Disadvantage of a Steel Injection Mold


Steel Injection mold is one of the most commonly used methods of producing identical plastic products in high volumes. They can suffer from extremely high pressure. As a result, the plastic within the mold is pressed harder and allows for a large amount of detail to be imprinted onto the part and for complex shapes to be manufactured.

There is a large selection of polymer resins to choose from, even some of the corrosion resin can be molded from a steel injection mold. Such as 420 stainless steel is to be used in cavities and cores for Acetal or PVC material, but if the part size is too large for successful heat treat, use P-20 with corrosion-resistant plating can be another good option.

Steel injection molding is a stable and repeatable process: this is a huge advantage when trying to produce high tolerances and part reliability in high volumes.

Because steel injection tools are typically made from strong steel, it can be difficult to make design changes. If you need to add plastic to the part, you can make the tool cavity larger by cutting away steel. But in order to take away plastic, you need to decrease the size of the tool cavity by adding metal to it. This is extremely difficult and in many cases might mean scrapping the tool (or part of it) and starting over a new one.

How to Choose Right Materials for Plastic Injection Molding


The choice of material to construct a plastic injection molded part is often a question of budget and the desired end-product.

If your parts’ demanded do not require over 5,000 parts, if you only want to process full fit and functional testing before the design is frozen, it is a good option to process with aluminum tooling which can discover any design flaws early on or avoid high investments on production tool.

Steel tools cost more to build, but their longer lifetime often offsets higher initial costs. They were typically only used in large-scale productions when thousands of parts needed to be produced. High-grade steels like H-13 and S-7 are tough metals, withstanding wear and constant pressures of plastic injection molding.  Stainless steel injection molds are commonly used for larger components or clear parts, like lenses.

At Mastars, both aluminum tooling and steel tooling services can be found out to support your business. DFM and mold flow analysis will be provided free of charge at the RFQ stage, our team is here to bring you the best solutions and innovative concepts to accommodate your technical or timing requirements. We can support you with tool optimization or molding concepts to achieve economic benefits. And the potential production risky can be foreseen and take action to prevent it before the tooling launch.

How to choose the best materials for plastic injection molding? Do you need any R&D support? Please contact one of our technical sales team at Our professional team that produces top-quality prototypes and products can offer a one-stop service to support your future business in win-win situations.

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