PET Drying Windows and the Hydrolysis a Moulder Absorbs
Excess residual moisture causes instant ester chain hydrolysis in molten PET, dropping intrinsic viscosity and destroying mechanical part strength.
Scrap Multiplier
Meaning
Mathematical factors adjust the total resin requirement of a production run to account for material lost to sprues, start-up waste, and defective parts. Incorporating a scrap multiplier into the product cost model prevents underestimating the volume of raw material required to deliver a contract. This adjustment ensures that material purchasing aligns with actual factory yields.
Material Yield
Excess material consumed during initial process set-up cannot be recovered as virgin resin. Using a scrap multiplier helps the moulder account for these startup losses and the material trapped in cold runners. This calculation secures appropriate pricing.
Economic Factor
High reject rates raise the required quantity of raw resin to complete an order. If a part relies on expensive resins, the financial impact of the scrap multiplier is high. This factor directly influences the quote.
Regrind Utilization
Sprues and rejected parts can often be granulated and blended back into the virgin resin feed at a controlled ratio. If regrind is permitted by the customer, the scrap multiplier is reduced because the material cost is partially recovered. However, when the specification demands one hundred percent virgin resin, the full weight of the wasted material must be paid for by the production yield, making process optimization to minimize start-up scrap highly valuable.