Insert Injection Molding for Water Pump Shaft Production | Custom Plastic Part Case Study

Background

The metal shaft of the water pump rotates at high speed, which can lead to loosening over time.

Challenges

The product has a complex molding process, requiring precise coordination between the metal part and the mold. It thus demands high technical skills from the production operators.
The quality requirements are stringent. The front cover has multiple A-grade surfaces, and dimensional accuracy and flatness tolerance must be within ±0.02mm.
Any defects such as air marks, flow marks, flash, and knit lines are prohibited. These defects can impact the product's performance, resulting in abnormal noise and reduced lifespan.

Solutions

The metal part that interfaces with the molded component is treated with knurling to increase the contact area between the plastic part and the product.
The metal part undergoes preheating treatment to enhance the adhesion between the metal part and the molded component, ensuring a stronger bond.

Results

Production efficiency: The yield rate increased from 82% to 98%.
Quality improvement: The occurrence of defective products has been completely eliminated, and the number of rework instances has been reduced from 7 pieces per month to 1 piece per quarter.