There are thousands of designers who design injection tolling plastic parts but there is an elite group within this large community who can actually design parts for injection molders. Injection molded product design evolves through many phases of development before all the parts are ultimately documented and released to a molder for production. This last step in the development process is the most critical, since design changes or corrections can no longer be made without significantly adding cost or project delays.
Unfortunately, plastic part design mistakes will be uncovered only after first article parts are inspected and evaluated by the project team. Even with today’s sophisticated mold flow simulation, 3D CAD interference checks, rapid prototyping and numerous other development tools, it is impossible for anyone to predict every potential problem for an injection molded part. However, there is a very simple, low-cost method for minimizing potential problems and virtually ensuring perfect parts. It’s called partnering with your molder, which is the focus of this article.
It doesn’t matter how well you think you know how to properly design parts for plastic injection molding—you should always form a close partnership with your preferred molder as early in the design process as possible. Every molder has his or her own tooling preferences and techniques for molding parts, which can have a significant effect on part design. These subjective preferences can influence any of the following major design-related parameters affecting an injection molded part:
- Material options and consequences
- Critical tolerances
- Sink marks
- Steel safe areas
- Gate location
- Shut-off angles
- Draft angle orientation
- Texturing and draft
- Scheduling of critical start-up phases
- Secondary operations and fixtures
Suzhou HuiTong HuiChuang Technology 