Injection Molding: Aluminum vs. Steel Tooling

Picking the best injection mold for an industrial application starts with choosing between aluminum and steel for the base of the mold. Industry experts often talk about the potential benefits of using aluminum injection molds instead of steel units. However, the requirements are different for every project, and various applications are more suitable for steel tools. Here is a comparison of the benefits and disadvantages of injection molding aluminum and steel molds when considering key factors. 

Tooling Cost

There are differences in the costs for producing molds based on the materials used. At Global Design & Development, we specialize in constructing both aluminum and steel molds. Aluminum injection units are initially less expensive than steel molds to manufacture. If a customer wants a smaller upfront investment, aluminum may be the best tooling choice. However, the overall value of the tool depends on other factors, including the intended production lifespan. 

Low Production

If a customer plans to use the tooling primarily for low-volume production runs, aluminum molds are the best choice. Aluminum molds have low upfront costs and can produce hundreds of reliable parts. Paying more for steel may not be worth the initial investment if the mold is not used for high-volume manufacturing runs. 

High Production

Steels molds are strong, durable, and suitable for high-volume production. While the integrity of aluminum molds can break down after repeated use, steel molds can last for years with routine care and maintenance. Steel iterations are more expensive to produce initially but will last for multiple production runs. 

Complex Resins

Both steel and aluminum can handle a wide variety of molding resins, particularly commonly used materials. However, steel is the best choice for dealing with more advanced resin formulations. If a molding will incorporate more complex materials such as glass, steel is the best option as it is more durable and does not scratch easily. Aluminum is less durable, and the finish of the mold may be more easily affected by additives in the resin.

Heating and Cooling Times

Aluminum injection molds can dissipate heat much more quickly than steel molds, making them an ideal choice for manufacturers that require a quick heating and cooling process. The cooling time needed for the injection molding process can make the overall cycle time significantly longer. Aluminum is a good choice for companies that need to begin producing parts on a short turnaround schedule.  

Modification and Repair Issues

Steel molds are tough and durable, making them difficult and expensive to repair or modify. If a customer anticipates making changes to an injection mold in the future, aluminum may be the better option. Aluminum molds can be repaired and modified more easily than steel molds and at a much lower cost. 


Steel molds are highly durable and can withstand harsh working environments. If the tool is expected to be used repeatedly for long production runs, steel is a good choice. Aluminum units are cheaper to produce but can cost more over time as they tend to break down after repeated use and must be replaced. Steel molds can translate to a lower cost per part if used for high-volume production runs over many years. 


There are advantages and disadvantages to both injection molding aluminum and steel molds. Steel units are durable but more expensive to produce initially, while aluminum molds require less upfront investment but may break down after repeated use. Research should be conducted to ensure the best material is chosen for a particular application. Global Design & Development specializes in developing both steel and aluminum injection molds for a variety of applications, working with customers to construct high-quality parts for their industries.