The mold expansion - induced deformation in injection molding is a thorny issue, harming product quality, potentially damaging the mold, and reducing production efficiency. Here are solutions:
Reduce Injection Pressure
High injection pressure can cause mold expansion. Adjust the injection molding machine's pressure based on product structure, size, and plastic properties. For small, thin - walled, simple - structured products, if 120MPa causes expansion, reduce it by 5 - 10MPa increments until an optimal value (e.g., around 90MPa) ensuring complete filling without expansion is found. Record adjustments for future reference.
Reduce Injection Speed
Fast injection speeds can lead to mold expansion. Slow it down to let the plastic melt fill the cavity smoothly. For a large, complex part with an 80mm3/s initial speed, reduce it to 50mm3/s or lower. But beware, too slow a speed may cause early cooling and short - shot defects. Balance all product - quality aspects during adjustment.
Adjust Holding Pressure and Time
Excessive holding pressure or time can result in mold expansion. Consider product wall - thickness distribution, dimensional accuracy, and plastic shrinkage when setting these parameters. For an uneven - wall - thickness product, start with an initial setting (e.g., 60MPa for 10s), then fine - tune. Adjust pressure by about 5MPa and time by 1 - 2s each time until the right combination (e.g., 50MPa for 8s) eliminates expansion and meets quality standards.
