Injection Mold Tooling and Design

Designing the mold and its various components (referred to as tooling) for complex, critical-use plastic parts and products is a highly technical and often complex process. When the right tooling decisions are made, production is optimized, costs are reduced, and quality and customer satisfaction are improved.

In general, complex injection-molded products with tight tolerances require complex molds. This is where the rigor of the scientific molding process comes into play—Kaysun engineers rely on their in-depth knowledge and training about material behavior and mold design to construct the highest-quality mold for the project.

The Importance of Material Selection in Your Tooling Design

An important tooling design consideration is selecting the proper grade of steel. The correct steel hardness must be determined to maintain the proper balance between wear and toughness so tooling components don’t wear out prematurely. The mold is one of the most expensive parts of the injection molding process—we engineer them with the proInjection mold metals comparison for tool designper design and materials so they have the longest possible life with minimal maintenance. Some of the main factors to consider are:

  • the size of the production run
  • the complexity of the part
  • the finish quality needed
  • the material to be molded (some plastics are corrosive; others contain abrasive glass fibers)

The hardest metals, such as H13 steel, are best for high-volume, high-complexity parts. Softer metals, such as aluminum, can be sufficient for smaller runs and simpler parts. In general, the softer the metal, the easier and less expensive it is to machine. This diagram compares the expected tool life of aluminum, P20 carbon steel, and H13 hardened steel according to the size of the production run.

Debugging the Mold and Refining Prior to Production

After considerable preparation regarding product design and process selection, the mold is constructed—a big step toward production. However, to ensure consistent and repeatable production of flawless molded parts, the mold must be challenged completely before it’s called into action. This is one of the most important jobs of the process engineer.

Our engineers love “debugging” molds because it is a test of how well they have designed them. They push the mold relentlessly under realistic conditions (and sometimes beyond) to see where adjustments may be needed. Mold debugging is a critical step in creating a highly efficient and low-cost production process—ensuring top quality and repeatability.

In-House Design and Mold Adjustments

Injection molders rely on outside mold builders to custom-build the initial mold. Molds rarely arrive with perfect dimensions; typically, after the mold is debugged, adjustments are required to assure all design specifications are met. For most injection molders, this requires sending the mold out for final adjustments, which can take a month or more to complete. At Kaysun, we make most of these adjustments in-house and “fine tune” molds after initial sampling to improve the mold core/cavity geometry and achieve the desired dimensions.

The main goal of mold design and tooling is to create a product with highest possible manufacturability. That means a high-quality process that is simple and efficient, long-lasting, easy to operate and maintain, and that meets all customer specifications—all at the lowest possible cost.

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Tooling Design for Injection Molding