What they are
The sprue and runners are the channels that carry molten plastic from the machine nozzle to the cavities. In cold-runner tools this material solidifies each shot and is trimmed off; it may be reground or scrapped.
Why it appears in quotes
Hot-runner systems keep these channels molten, reducing waste and cycle time but raising tool cost. For high volumes the maths can favour hot runners — ask for both options if volumes are large.
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