The use of aluminum in injection molding has increased in recent years due to its ability to produce lightweight parts with high strength. However, the use of steel tooling is still preferred for certain applications because it can be made thinner and stronger than aluminum.

Aluminum injection mold tool life is a lot shorter than steel. The aluminum injection molding process has a short lifespan due to the high temperature of the molten metal.

It’s critical to choose between steel and aluminum for your injection tooling material since each has its own set of advantages in the manufacturing process. Because the needs for each project change, it’s always necessary to weigh the many choices, and selecting the right material is critical in production.

This article examines the criteria for selecting each mold type when using plastic injection molding services, as well as the benefits and drawbacks of each, as well as a thorough comparison of aluminum and steel tooling.

Why Is Tooling Material Important in Parts Manufacturing?

Each mold material has its own set of characteristics and uses. As a consequence, you must choose the most appropriate materials for your project in order to get the greatest outcomes. 

Although the variations between steel and aluminum tooling are minor, they are sufficient to create difficulties if they are not selected properly. Tooling made of the right materials guarantees a smooth production process. The size of the manufacturing line and the pace at which it runs are other important variables to consider when selecting tooling materials. 

How Do You Pick the Right Injection Molding Tooling for Plastic Injection Molding?

Because each mold material has its own individuality and qualities, many considerations go into determining the best tooling for a particular project. The criteria needed to select the suitable tooling are listed below. 

  • High Volume vs. Low Volume

Aluminum is better suited to and provides greater value for low-volume manufacturing runs of less than a million pieces. This material offers lower initial costs and can manufacture components in the hundreds and tens of thousands with less wear. Aluminum is an excellent choice for production components that need to be made in a matter of days or weeks. 

Steel is the finest choice for large volume and numerous manufacturing runs. Millions of components are produced using steel molds, all of which are of the highest quality. With appropriate maintenance, the greater initial investment cost pays off in the long term with equipment that lasts for years. Steel’s strength also makes it more suitable for longer manufacturing runs. As a result, keep an eye on your project details to make sure you’re using the appropriate tools for the job.

The component material has an effect on the tool’s life expectancy and is an important consideration when choosing tooling. Will it be a gentle substance, or one that is more aggressive, or one that can handle a lot of heat? 

Steel and aluminum are both compatible with a wide variety of injection molding materials. Steel, on the other hand, is better suited to more complicated compositions that include glass, fiber, and other additives. 

Aluminum is softer than steel and is more susceptible to damage from additives and abrasive resins, compromising the quality of the finished components. Because of its low density, texture selection is also restricted when tooling with aluminum.

  • Budgeting (Tooling Cost & Cost per Part)

Aluminum tooling is more cost-effective than steel tooling when it comes to producing injection molded components. The value and return on investment of both molds differ depending on how they are used. Aluminum tooling has a lower initial investment cost than steel tooling and is a better value for low-volume manufacturing. 

The cost per component is determined by the planned manufacturing run and the expected lifetime of your parts. Aluminum is a better choice for shorter manufacturing runs since the molds are less expensive up front, resulting in reduced per-part costs. Steel molds are suitable if your manufacturing volume is in the millions or tens of millions. Because of the extended service life provided by the mold, the expense per component pays out in the long term. 

  • The passage of time (Tooling Time & Heat and Cooling Time)

Aluminum tooling conducts heat from the mold faster than steel molds, allowing it to heat and cool seven times faster. It also has a shorter machining time, which cuts down on mold-building time. 

Injection molding takes up the majority of the total cycle time. When suitable, using an aluminum mold reduces cycle time, resulting in quicker component manufacturing. The length of time it takes to complete a project is determined by a variety of variables, including design complexity, surface qualities, and unique feature inlays.

Steel tooling, owing to its extreme hardness and strength, outlasts aluminum in terms of longevity. It can endure repeated usage for long periods of time. As a result, it’s ideal for high-volume manufacturing. The mold’s high initial cost is repaid over time due to its frequent usage. 

Aluminum tooling, on the other hand, is not as durable, and after a few thousand manufacturing cycles, the molds begin to show signs of wear and tear.

  •  Dimensions and complexity of the parts

The choice of molding is influenced by the size and shape of the components. For components that need a more polished and complicated design, such as thin walls, less rounded corners, and so on, steel molds are better than aluminum molds. 

Steel’s strength and hardness enable it to maintain its form in high-precision regions. The intricacy of components is supported by steel molds. Steel molds provide more surface finishing choices than aluminum molds, which are best for basic designs. 

  • Shrinkage, warping, and other flaws

Aluminum has a better heat dissipation than other metals. As a result, the mold may achieve quicker consistent heating and cooling periods. It also reduces the number of defective or rejected components. Sink marks and voids are often caused by inconsistencies in heating and cooling. Aluminum’s quicker heat dissipation reduces the amount of components that are rejected owing to shrink wrap and other faults. As a result of the lower component rejection rates, aluminum molds provide greater cost benefits. 

  • Maintenance and Tooling Modifications

Because of the hardness of the materials, repairing damaged steel molds is difficult and costly. If a manufacturing mistake occurs, engineers usually start again with a fresh mold. Aluminum molds, on the other hand, are simpler to alter and repair. This is due to the fact that they are constructed of softer materials that may be changed in the event of a manufacturing mistake.


Cost, component materials, production volume, time, maintenance, and time all play a role in selecting the appropriate plastic injection molding tooling throughout the manufacturing process. Before you begin manufacturing, you must be well informed of your project’s overall needs and specifications, as they will serve as a guide to selecting the appropriate tooling for your project. You may save time and money by choosing the appropriate tools.

Aluminum is a lightweight metal that is easy to work with and can be molded into a variety of shapes. Steel tooling, on the other hand, is stronger and more durable than aluminum. Reference: aluminum prototype mold.

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Frequently Asked Questions

Why plastic flows better in aluminum injection molds?

The melting point of aluminum is lower than the melting point of plastic, so molten aluminum will flow into a mold cavity more easily.

Can aluminium be injection molded?

Yes, aluminium can be injection molded.

What type of tool steel would you use for an injection mold?

The type of steel that would be used for an injection mold would be a tool steel.

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  • how to make aluminum injection molds

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