Choosing the right runner system
Runner and gates solidify with part. Pros: lower cost, easier color changes. Cons: 15-30% material waste, longer cycle.
Runner kept molten. Pros: no waste, faster cycle, multi-cavity. Cons: 30-60% higher mold cost, complex temp control.
Cold runner: Small volumes, prototyping, frequent color changes. Hot runner: High volume, expensive materials, large parts.