Why and How to Design Injection Molding

Injection molding is a commonly used manufacturing process that involves injecting molten material into a mold in order to create a part or product. This process is used across a variety of industries, including automotive, medical, and consumer goods. However, in order to ensure that the injection molding process is successful, proper design is essential.

But to leverage its benefits fully, parts must be designed properly for the process. Here is an overview of key design guidelines for injection molded components.

Benefits of Injection Molding

Reasons to use injection molding include:

• High production rates and low cost at volume
• Precision repeatability and dimensional accuracy
• Complex geometries and detailed features
• Wide range of thermoplastic material options
• Insert molding allows hybrid plastic/metal parts

Design Considerations

To maximize these benefits, injection molded parts should be designed with certain guidelines in mind:

Wall Thickness

• Maintain uniform thickness where possible for even cooling and shrinkage
• Recommended wall thickness is 1-3 mm for most materials
• Thicker walls increase cooling time and can induce sinks, warpage

Radii and Draft Angles

• Add radii to interior corners to avoid stress concentrations
• Include draft angles of 1-3° on vertical walls for demolding

Ribbing and Gussets

• Use ribs and gussets to strengthen parts rather than increased wall stock

Avoiding Sinks and Voids

• Strategically place gates, runners, and vents to minimize defects
• Account for material shrinkage as plastic cools

Simulation and Analysis

CAE tools like mold filling and warp analysis help assess manufacturability before tooling is built. An experienced design engineer can ensure parts are optimized for the injection molding process.

Injection molding is an important manufacturing process that requires careful attention to design in order to achieve successful results. Whether producing industrial cameras or industrial lenses, it is essential to work with experienced professionals who can provide guidance and support throughout the design process.

Here are some additional thoughts on best practices when using injection molding to produce industrial cameras and lenses:

• Optimize wall thicknesses and geometries to ensure even flow and cooling of plastics to minimize warpage that could impact lens or sensor alignments.
• Perform mold flow simulations early in the design stage to identify and correct issues with fill rates, weld lines, air traps etc. This avoids defective molds.
• Use gate locations strategically to minimize part stresses, sink marks, and blemishes in critical optical surfaces.
• Consider anisotropic material flow behavior and fiber orientations when using reinforced plastics. Proper flow paths enhance strength.
• Avoid fragile shutoff features and complex sliding/lifting actions in molds to maximize durability and lifespan.
• Factor in material shrinkage rates and thermal expansion coefficients when designing precision locating features.
• Simulate stresses and include appropriate ribbing/gussets to reinforce thin-walled sections prone to warpage.

Account for mold design rules like draft angles, radii, and other specialized requirements.

Collaborating early with experienced injection molding partners helps avoid pitfalls and produce precision molded parts meeting optical and geometric tolerances for industrial cameras and lenses. Careful design is essential to leverage the benefits of this manufacturing process.