The phenomenon of burn marks in Plastic Injection Molding is primarily characterized by localized areas of the product turning yellowish or black, presenting a charred state. Burn marks typically occur at the final molding location of the product, often due to material decomposition caused by excessively high temperatures.
Causes of Burn Mark
Injection speed too fast.
Injection pressure too high.
Plastic residence time too long.
Injection molding machine temperature too high or too low.
Poor mold cavity venting.
Improper mold temperature control.
Remedies for Burn Mark
Employ multi-stage injection: fast-slow.
Check hot runner temperature, reduce hot runner temperature.
Use a smaller diameter material barrel.
Choose high-quality plastic pellets, and do not store them for too long.
Design mold structure reasonably.
