Meaning
Moulding diagnostics that determine the exact duration required for the plastic in the gate to solidify provide a baseline for the packing phase. Process technicians perform a gate freeze analysis to avoid wasting cycle time or causing material backflow into the runner system. The evaluation involves measuring part weight at incremental hold times until the weight plateaus, indicating no more material can enter the cavity.
This boundary defines the threshold beyond which additional hold pressure has no physical effect on the part.
Weighing Method
Precision scales are utilized to measure the molded samples to within thousands of a gram for accurate tracking. When executing a gate freeze analysis, the weight of the parts is plotted against the hold time on a line graph. The curve flattens completely once the gate is frozen and no more polymer can be packed into the cavity.
Cycle Optimization
Running the hold stage beyond the solidification point increases energy consumption and extends the overall cycle time needlessly. By applying the results of a gate freeze analysis, the holding phase can be set to the minimum necessary time. This optimization maximizes production throughput without sacrificing the dimensional quality of the parts.
Defect Prevention
Premature release of holding pressure allows molten plastic to flow out of the cavity and back into the runner. Failing to perform a gate freeze analysis can result in sink marks, void formation, and low part weight. Consistent holding times ensure that each molded part achieves its intended density.
