Even with the most advanced injection molding equipment, rubber parts can experience defects if design, material, or process considerations aren’t addressed. Understanding these common issues can help you create parts that are durable, precise, and reliable.

1. Flash

What it is: Excess rubber that seeps out between the mold halves, forming thin sheets along the edges.

How to prevent it: Ensure molds are properly maintained and aligned, and that injection pressure is optimized. Primo Rubber Co. inspects molds regularly and monitors pressure to minimize flash, reducing post-production finishing.

2. Voids or Air Pockets

What it is: Hollow spots or gaps inside the molded part caused by trapped air or uneven material flow.

How to prevent it: Proper venting and well-designed flow paths allow air to escape. Selecting the right material viscosity and injection parameters also reduces the likelihood of voids. Our team works with you to design molds and processes that ensure consistent fill.

3. Sink Marks

What it is: Depressions or dimples on the surface, often caused by thick sections cooling unevenly.

How to prevent it: Maintain uniform wall thickness, avoid overly thick sections, and consider post-curing processes to stabilize dimensions. Primo Rubber Co. advises on part geometry to prevent these common cosmetic and functional issues.

4. Shrinkage and Warping

What it is: Dimensional changes or bending after curing due to uneven material flow or stress.

How to prevent it: Select materials with predictable shrinkage, and design parts with tolerances that account for expected dimensional changes. Our experience with multiple compounds ensures your parts meet specification every time.

5. Surface Imperfections

What it is: Marks, blemishes, or rough textures caused by mold imperfections or contamination.

How to prevent it: Regular mold cleaning, inspection, and maintenance are essential. We take care of the molds and maintain strict quality checks to produce smooth, defect-free surfaces.

Partner with Primo Rubber Co.

At Primo Rubber Co., our experience in rubber injection molding allows us to foresee potential defects before production begins. From initial design consultation to final inspection, we provide the expertise, tooling knowledge, and quality control needed to deliver custom rubber parts that are consistent, durable, and ready for your application. Contact Primo Rubber Co. today to learn more about our custom rubber molding capabilities and material options.