Meaning
Material verification protocols that inspect only selected shipments from a series of deliveries reduce the cost of quality assurance. Injection moulding plants implement skip lot testing when a resin supplier has demonstrated a long history of zero-defect raw material shipments. This inspection strategy shifts resources away from redundant testing of highly reliable polymer grades.
Supplier Qualification
Establishing this reduced testing routine requires the raw material manufacturer to meet strict quality performance criteria over a specified period. The polymer compounder must deliver a consecutive number of resin lots that pass every incoming inspection test, such as melt flow rate and moisture analysis. Once the supplier reaches this certified status, the moulder transitions to inspecting only every third or fourth incoming lot of material.
This partnership lowers transaction costs for both companies while maintaining high standards of quality control.
Inspection Protocol
Random selection algorithms determine which incoming shipments of resin will be subjected to laboratory testing. The unselected batches bypass the receiving lab and move directly into production or raw material storage areas. This optimized approach reduces the bottleneck at the receiving dock and keeps material flowing to the presses.
If a single tested lot fails, the system automatically reverts to full testing for all subsequent deliveries.
Risk Exposure
Reducing the frequency of raw material testing introduces the risk of processing an out-of-specification batch of resin. If a defective lot slips through, it can cause high scrap rates and damage injection moulding tooling. Moulders must balance these testing savings against the potential cost of sorting and discarding defective molded parts.
