How Wall Thickness Impacts Injection Mold Part Design

Ensuring consistent wall thickness in your injection molding part design is crucial for various reasons. It helps prevent issues like sink, warping, twisting, and cracking, as abnormal shrinkage is avoided. Additionally, maintaining uniformity enhances the part’s ability to manage stress and improves its overall structural integrity.

Choosing an optimum wall thickness during injection molding also mitigates problems such as short shot, which occurs when the mold cavity is incompletely filled. By achieving a steady flow of material through the injection molding tool, you can avoid complications like air trapping, unbalanced filling, and weld lines. This enhances moldability and ultimately improves the cost-effectiveness of producing your parts.

Furthermore, optimizing wall thickness offers cosmetic benefits by reducing blemishes and imperfections, resulting in a more visually appealing plastic part.

To assist you in designing parts with optimal wall thickness, Quickparts experts have provided a set of guidelines. These suggestions not only improve the durability of your parts but also help optimize the cost of injection molding them.

Design Guidelines for Optimum Wall Thickness:

  1. Consider plastic part wall thickness to minimize expensive tooling changes, reduce material costs, and prevent part failure.
  2. Increasing wall thickness by approximately 10% provides a stiffness boost of around 33% for most materials.
  3. Ribs should be 40% to 60% of the thickness of adjacent walls to prevent sink.
  4. Remove unnecessary thickness and wall stock by coring out.
  5. Avoid sharp internal corners and long unsupported spans, incorporating radius on inside corners to reduce stress impact.
  6. Utilize ribs as stiffening features and supports to achieve equivalent stiffness with less wall thickness.
  7. Consider incorporating curves and corrugations into your design for added strength and durability.

The choice between thinner or thicker walls depends on your specific design and the type of resin used. However, there are advantages to opting for thinner walls whenever possible. Thinner walls reduce material usage, resulting in cost savings and lighter parts. Additionally, faster cooling times can be achieved with thinner walls, reducing production time and associated costs. Thin walls also help minimize warp and sink marks caused by differential cooling rates, improving the overall quality of the part. Nevertheless, structural integrity should not be compromised for thinness, and maintaining uniform thickness remains vital for moldability.

The selection of the appropriate material for your part design significantly influences wall thickness. Material selection should be based on the desired performance and operating conditions of the final part. It is essential to thoroughly understand the required characteristics before choosing from the wide range of available resins. Material properties not only impact wall thickness but also affect strength and durability. Quickparts provides recommended wall thickness rules for 13 commonly used plastics in injection molding.

Once you have determined the optimum wall thickness for your plastic part, it is crucial to evaluate the design to ensure its performance. Quickparts’ team of experts can assist in identifying design faults, guiding you through necessary modifications, and advising you during the material selection process.

Quickparts offers the following services:

  1. A range of plastic options for your consideration.
  2. Evaluation of material options based on your design dimensions.
  3. Application of best practices to ensure successful design and product delivery to the market.

About Quickparts: Established in 1996, Quickparts & Engineering is a leading innovator in on-demand digital manufacturing, specializing in injection molding and rapid prototyping. Their expertise, engineer-centric approach, and commitment to delivering high-quality products on time and within budget have earned them the trust of tens of thousands of product developers and engineers across North America.

For any questions or inquiries, please contact their friendly sales team at the provided email or phone number: [email protected] or 931-766-7290.

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