Manufacturing Complex Injection Molded Parts: Challenges & Tips

custom plastic injection molding from MSI

Custom plastic injection molding is a widely utilized manufacturing process for producing complex plastic parts. However, certain product features and plastic materials can present challenges during the production of these molded parts. 

In this article, we’ll explore the key features that make molded parts complex, the types of plastic materials that pose difficulties, proactive steps that can be taken to overcome these challenges, and the benefits of working with an experienced plastic injection molding manufacturer.

Product Features That Contribute to Part Complexity

Three primary features that add to a plastic molded part’s overall complexity: threads, over-molding, and undercuts.

Parts With Threads

Injection molding threads require precise tooling and careful consideration of the thread geometry to ensure proper functionality. Working closely with an experienced injection mold manufacturing partner can help achieve accurate thread formation.

Parts Requiring Overmolding

Overmolding involves molding one material over another, and it demands precise alignment and ensures adhesion between materials. 

Parts with Complex Undercuts

Undercuts are features that prevent the easy removal of a molded part from the mold. Complex undercuts often require specialized tooling and careful mold design, which can be expertly provided by an experienced injection molding supplier.

Plastic Materials Presenting Challenges

In addition to complex part designs, there are challenges during the material selection process too. The materials used to produce plastic molded components will vary based on specific application requirements and the environment the part will be expected to perform in.

The most challenging plastic materials to work with are high-temperature, moisture-sensitive, and warp-prone materials.

High-Temperature Materials

Certain plastics, such as PEEK or PEI, have high melting points, requiring precise temperature control and specialized equipment during molding to avoid degradation or insufficient flow. A skilled injection molding supplier understands the intricacies of processing high-temperature materials effectively.

Moisture-Sensitive Materials

There are also plastics like PEI and nylon that are highly sensitive to moisture content. Proper drying techniques and moisture control during processing are crucial to prevent defects. Not all injection molding companies have drying equipment for elevated temperatures and moisture analyzers. Check with your custom plastic injection molding partner early in your project if your part requires this.

Warp-Prone Materials

Polypropylene and polyoxymethylene (POM) tend to warp after molding. Proper mold design, cooling, and stress-relieving techniques provided by an experienced injection molding manufacturer can mitigate this issue.

 Proactive Steps for Manufacturing Complex Molded Parts

  1. Part Design Validation by Rapid Prototyping: Rapid prototyping techniques, such as 3D printing, allow for the quick production of physical models to evaluate part design and functionality before investing in expensive molds. Collaborating with an injection molding supplier that offers rapid prototyping services can expedite the design validation process.
  2. Mold Flow Analysis: Utilizing computer simulations, mold flow analysis identifies potential issues in the filling, packing, and cooling stages of the molding process, enabling adjustments to optimize part quality and reduce defects. Working with an injection mold manufacturing partner with mold flow analysis capabilities ensures thorough evaluation and optimization of the injection molding process.
  3. Design for Feasibility Reviews: Collaborative reviews involving designers, engineers, and mold manufacturers can help you identify potential manufacturing challenges early in the design phase, leading to modifications that simplify production. 

Get Help Manufacturing Complex Injection Molded Plastic Components

Manufacturing complex injection molded parts requires collaborating with an expert. An experienced plastic injection molding company can help you identify potential design errors, select the best material for your component, and resolve challenges as they occur. 

If you need help manufacturing plastic molded components, turn to MSI Mold. Founded in 2009, we’re a U.S.A.-based plastic injection molding manufacturer with rapid prototyping, design and engineering, and assembly capabilities, and we can handle high- and low-volume orders. Please contact us today to learn more about our capabilities or to schedule a free design consultation.