Excessive Flash in Vertical Molding: Causes and Fixes

Vertical injection molding is now used for everything from baby and household products and consumer electronics to irregular components, automotive parts and power cables. One of the most common issues our after-sales engineers are asked about is excessive flash.

• Insufficient clamping force: check clamping force against the mold structure and size and make sure it is sufficient.
• Shot volume too large: reduce shot volume.
• Injection pressure too high: lower injection pressure.
• Mold temperature too low: raise mold temperature.
• Insufficient mold machining accuracy: inspect and analyze the mold.
• Material viscosity too low or curing too slow: increase material viscosity or speed up curing.

Work through these causes one by one to find the root cause. Short shots are the opposite problem and are analyzed in the opposite direction.

In one case, working together with the customer's process engineers, our after-sales team brought the yield on a vertical machine to 98.6%.