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By Jeremy Losek, Sep 14th, 2021

steel injection mold

Steel vs. Aluminum for Plastic Injection Molds

ICOMold has always used steel material for our plastic injection molds. Many of our competitors, on the other hand, make their molds out of aluminum. There are several advantages of using steel injection molding over aluminum injection molding, which we will explain here.

Advantages of Steel Over Aluminum Molds

Steel Injection Molds Have the Ability to Make Complex Parts

A part design can be, in some cases, too complex to be injection molded with an aluminum mold. A steel mold will be required due to the complexity of the part geometry. This is not unique to ICOMold – this is a universal limitation that all mold makers face.

More Surface Finish Options with Steel Injection Molds

Steel molds offer more options when it comes to part surface finishes. The high-density nature of steel allows more texture selections and tall, deep details in the tooling can be achieved by adding steel inserts. The number of surface finishes possible with an aluminum mold is limited, and custom finishes are not possible as they are with steel molds. The difference in available surface finishes based on mold material affects all mold makers, not just ICOMold.

Ease of Design Modifications

Mold modifications due to part design changes are limited on aluminum molds compared to steel. For one thing, a steel mold can be modified by welding. If a part re-design requires less plastic in an area, and therefore, more steel in that area of the injection mold tooling, the steel tolling can be modified. This is not the case with aluminum. If there is a good chance that your part may be undergoing design revisions that will require mold modifications, a steel mold can better accommodate that.


Less Flash

Because steel is harder, there is less chance for flash on the part as there is with using a softer, aluminum mold.

Steel Injection Mold Tooling Can Produce Parts in Higher Volume

Steel injection molds can withstand high injection pressure and temperature, making them resilient throughout the manufacturing process. They can handle multiple cycles, producing parts in high volume before replacement.

Steel Molds Have the Ability to Handle Aggressive Materials

Injection molded material can make an impact on the life expectancy of the tool. Steel injection molds can be hardened through heat treatment and become extremely durable, thus granting them the ability to handle aggressive material such as ASA/glass-filled Nylon and Ultem. These aggressive materials require high injection pressure and temperature that only steel injection molds can achieve over aluminum molds.

Steel Molds Have High Durability

While aluminum molds will hold up for smaller part runs, steel molds are more durable. Steel Injection Molds have excellent corrosion resistance, wear and tear resistance, and thermal stability. These characteristics allow the steel injection molds to achieve higher production cycles and withstand non-conformities in the product. For aluminum molds to reach the same hardness of steel, they must be anodized or plated with nickel, which increases the tooling cost, negating the benefit of aluminum generally being less expensive. Our steel production molds carry a lifetime warranty – if your mold ever requires any repairs, we will cover the cost of repairs, or even replacement, for the entire time we are producing your parts for you.

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