It is better if can custom ejector bar, but the processing cost is relatively high. Nowadays many moulds structure is used standard parts; the quality is at conventional level. If the gap between ejector bar and guide hole is too large, the leakage will occur; but if the gap too small, the mould temperature will increase during injection molding, causing the plunger to expand and stuck, and sometime even the ejector rod will stop and deformed, resulting the higher part of ejector bar cannot return and directly hit the cavity.
If this problem occurs, the mould ejector bar should be repaired. The top of the bar need retain 10-15mm, the middle part milled 0.2mm smaller. All bars assembled, check all gaps strictly. Usually the gap in 0.05-0.08mm, to ensure the entire ejector bar can advance and retreat freely.
The cooling effect of the mould directly affects the quality and production efficiency of the product. Such as poor cooling, big and uneven shrinkage causes warping defects; on the other hand, the whole mould or part of the mould overheating, so that the mould cannot be properly formed and discontinued.
Cooling system design and processing is based on the shape of the product. We can omit the processing just because the mould structure is complex or difficult, especially for large and medium-sized mould, we must fully consider the cooling problem.