Aluminum Soft Plastic Molds vs. Steel Molds

Apr 20, 2021

What You Need To Know About Aluminum Soft Plastic Molds

Selecting an appropriate injection molding material is not a straightforward task. It is a vital decision to make in the production process. Choosing the wrong material can cost you additional budgets by making tooling adjustments and so on. Therefore, you need to be sure that you chose the most appropriate material for the process. For every product designer, it is critical to choose between steel and aluminum soft plastic molds. It is crucial because the selected tool impacts part cost, quality, and cycle time, etc.

aluminum soft plastic molds

Therefore, it becomes essential to understand how different materials would work during the process of injection molding. Read this article to go through the information you need to make an informed decision.

Steel and Aluminum Soft Plastic Molds

Steel and aluminum are the most commonly used materials for injection molding. However, it can be a little tricky to know which one should be the most appropriate material to choose for the production. To make this process a little easier for you, we will list a few advantages and disadvantages of both steel and aluminum soft plastic molds.

1. Aluminum for Injection Molding

The metal aluminum is soft and lightweight. It is also resistant to heat and rust and can easily be shaped into different forms. Due to its specific properties, it becomes a suitable material for injection molding. Many injection molding companies are using this metal to create many parts and components. Now, let’s go through the advantages and disadvantages of this material for a better understanding.


The first advantage of using aluminum instead of steel is its lower cost of tooling than steel. It is comparatively a more cost-efficient material to use than steel material for injection molding. Aluminum is a perfect choice for your low-volume runs due to its primary low-cost investment. Therefore, it becomes an ideal option for you if you want to produce parts in small numbers.

Another noticeable advantage of aluminum is its quick cooling and heating times. Aluminum heats up and cools down much rapidly than steel. As a result, you will be able to manufacture more components in a short time. Aluminum has a better heat dissipation which means that it heats more uniformly. Due to this, there are fewer chances of defects or rejected pieces.

One excellent benefit of steel over aluminum soft plastic molds is its easy repair or modification. You can repair and modify aluminum in a much easier manner because aluminum is a soft material. It is a massive benefit in a situation where you may get a production error.


On the other hand, aluminum material also comes with some possible downsides. You cannot rely on this material for longer production or high-volume runs. Therefore, you must keep in mind that this material is not suitable for high-volume production or longer runs. Another possible drawback of aluminum is that it might not be a compatible material with complex molding resins. Due to the soft nature of aluminum, it is also not an ideal choice for pieces that need great detail.

2. Steel for Injection Material

Steel is a combination of carbon and iron and a few more elements that equip it with unique properties. Due to the variety of such features, steel becomes an excellent choice for fabrication. Aluminum and aluminum soft plastic molds are currently the most popular injection molding materials in the market. Here are the advantages and disadvantages of steel material for injection molding.


Steel is a perfect material for high-volume production, and this advantage makes steel a superior choice to aluminum. Steel has a better strength, which helps it support high-volume productions. However, you will have to ensure proper mold maintenance if you want to enjoy its high-volume production benefits. It is also suitable for complex resins. Steel has better compatibility with standard resins, and you can also consider it for advanced formulas.

Due to the hardness and strength of steel, it is most suitable for products that require detailed features and high precision. Aluminum soft plastic molds are also known for superior durability. The steel alloy is perfect for extended production runs. Another significant advantage of steel is that it lowers the cost per piece.


On the other hand, steel material also has some disadvantages. For example, it is an expensive material as compared to its counterparts. Parts can damage during their production phase, and steel molds are not easy to repair because of their hardness. Moreover, steel is also more susceptible to warping and defects. Steel also takes a long time for heating and cooling that may slow down the production times.

Another disadvantage of steel material is that it is not suitable for low-volume production runs. Aluminum is a much better choice for low-volume production runs. Additionally, the initial tooling cost investment of steel is higher than the other available injection molding materials.

Cost for Creating or Changing Aluminum Molds vs. Steel Molds

The cost of creating steel molds is approximately ½ to ¼ the cost of making aluminum molds. Generally, the cost of steel tooling proves higher than aluminum tooling, even if you get price quotes from different Chinese vendors. The material type you select also impacts the budget for making mold changes. For instance, aluminum tooling would be approximately 1/10 the price of modifying steel tooling. The reason behind this is that steel is more rigid and takes more time to machine versus aluminum. You can get a free online quote from local vendors.

DIY plastic molding


In short, aluminum soft plastic molds offer value beyond sampling. It would be best if you chose steel molds over aluminum molds for high-volume runs. Aluminum molds are both time-effective and cost-effective for your injection molding project. On the other hand, steel molds are expensive, but they are better in terms of strength. Steel is also an ideal option for complex resins. You can compare the pros and cons of both materials to know which one is the most suitable choice for your project. We hope you find this article helpful in making a more informed decision.

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