What metal should you use for injection molding molds?

Injection molding is an efficient and versatile manufacturing method that creates complex and precise parts by injecting molten material into a mold cavity. In order to produce high-quality parts at a low cost and with a fast turnaround time, choosing the right material for the molds is critical. Molds made from the wrong material can wear out quickly, warp, corrode, or fail to provide the necessary detail and surface finish. In this blog post, we will discuss the main options for metal injection molding molds and their key properties and applications.


Aluminum is one of the most popular materials for injection mold tooling due to its high thermal conductivity, low density, and good machinability. Aluminum molds can withstand high temperatures and pressures and offer good dimensional stability and corrosion resistance. They are also relatively affordable and easy to modify or repair. However, aluminum is not suitable for some types of resins that are highly abrasive, corrosive, or have high viscosity, as they can cause wear, galling, or cold welding on the mold surface. In addition, aluminum molds have a lower hardness and a shorter lifespan than steel molds, which makes them more suitable for prototyping and short-run production.


Steel is the most common metal used for injection molding molds, particularly for high-volume production. Steel molds offer superior hardness, toughness, and wear resistance, which ensure a long tool life and consistent performance. They also provide a high degree of precision and surface quality, which is essential for many applications in industries such as automotive, medical, and aerospace. Steel molds can be made from several types of steel alloys, including pre-hardened steels (such as P-20 and H-13), stainless steels, and tool steels (such as D-2 and A-2). Each type of steel has its own advantages and limitations in terms of machinability, thermal conductivity, corrosion resistance, and cost. Some steel molds may require additional post-treatment, such as nitriding, coating, or polishing, to enhance their performance and durability.

Other metals

While aluminum and steel are the most commonly used metals for injection molding molds, there are other metals that can be used in specific circumstances. For example, copper alloys (such as beryllium copper or tellurium copper) can offer high thermal conductivity and resistance to thermal fatigue, which make them suitable for molds that need to rapidly cool down the resin after injection. However, copper alloys can be expensive, difficult to machine, and have limited surface finish options. Magnesium alloys can also be used for molds that require low weight and high stiffness, but they are more prone to corrosion and have limited availability.


Choosing the right metal for injection molding molds depends on various factors, such as the resin type, the production volume, the part design, and the budget. While aluminum and steel are the most common choices, they have different properties and applications that should be carefully evaluated. Other metals, such as copper and magnesium, can provide additional benefits in specific scenarios but require more specialized knowledge and equipment. Ultimately, selecting the best metal for injection molding molds requires a balance between performance, cost, and feasibility, and can significantly impact the success and profitability of the production process.

what metal is used for molds injection molding

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Our rapid injection molding Application

Sigma Technik Limited's rapid injection molding service injects molten plastic materials into molds using injection molding machines and molds, and cools and solidifies them over a certain period of time, ultimately forming the required plastic parts. This manufacturing process is usually suitable for producing small and medium-sized plastic parts, which can obtain high-quality and precise parts in a short period of time.

Plastic Injection Molding

Injection molding is a common manufacturing process to produce low volume to large volumes of parts typically made out of plastic. The process involves injecting molten material into a mold and letting it cool to a solid-state.

Liquid Silicone Rubber Molding

Liquid Silicone Rubber is known as LSR, which is a process used to produce parts made from silicone rubber, widely used create products such as medical devices, automotive parts, baby care products, and many others.

2K Injection molding

2K injection molding is a manufacturing process in which two different types of plastic materials are molded together in a single operation to create a single homogeneous component. This process allows for efficient and cost-effective production of high-quality parts that can perform unique functions.

Overmolding and Insert Molding

Overmolding / Insert molding combines two or more materials into a single part, one of the material is usually soft and flexible, or metal. The purpose of overmolding/insert molding is to add functionality, improve grip, provide protection, or enhance aesthetics.

Mission And Vision

Rapid injection molding materials


ABS is a type of plastic with high strength, hardness, and toughness. It has good impact resistance and wear resistance, and is suitable for manufacturing shells, components, and models.


PC is a transparent, high-strength, high-temperature resistant, and excellent electrical insulation material. It is suitable for manufacturing transparent components, electronic components, and automotive components.


PP is a relatively flexible material with excellent corrosion resistance and high temperature resistance. It is suitable for manufacturing containers, pipelines, baby bottles, etc.


PA is a material with high strength, high rigidity, and wear resistance. It is suitable for manufacturing gears, bearings, brackets, etc.


POM is a material with excellent wear resistance, toughness, and rigidity. It is suitable for manufacturing gears, bearings, pulleys, etc.


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Sigma Technik Limited, as a prototype production company and rapid manufacturer focusing on rapid prototyping and low volume production of plastic and metal parts, has advanced manufacturing technology, one-stop service, diversified manufacturing methods, on-demand manufacturing services and efficient manufacturing processes, which can provide customers with high-quality, efficient and customized product manufacturing services and help customers improve product quality and market competitiveness.


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Rapid Injection Molding FAQs

Burrs appear on the surface of the product, which affects its aesthetics and safety. The solution can be to adjust the parameters of the injection molding machine, such as temperature, pressure, speed, etc., or to perform post-processing, such as polishing, sandblasting, etc.

The warping deformation of the product is usually caused by unstable parameters such as temperature and pressure of the injection molding machine, or improper mold design. The solution can be to adjust parameters such as temperature and pressure, or to redesign the mold.

The occurrence of bubbles inside the product may be due to the high temperature of the injection molding machine and the high moisture content of the material. The solution can be to reduce the temperature of the injection molding machine, adjust the water content of the material, increase the pressure of the injection molding machine, etc.

The product size deviation is too large, which may be caused by material thermal expansion, mold deformation and other reasons. The solution can be to adjust parameters and optimize mold design based on material characteristics.