Bio Based Grades Priced against the Composting Route They Need
Matching resin melt stability and wall thickness to regional waste facility residence times prevents unexpected landed part cost escalation.
Wall Thickness Penalty
Meaning
Economic and operational cost surcharges result from excessive material accumulation in injection moulded plastic part designs. Molders evaluate the wall thickness penalty through increased cooling times, higher resin consumption and elevated part weight when wall sections exceed structural requirements. The cost impact ceases when part designs are optimized using uniform nominal walls, ribbing and core-outs.
Cycle Time Impact
Polymer cooling inside injection mould cavities follows a square-law relationship with section thickness, doubling wall thickness quadruples required cooling time. Accumulating a wall thickness penalty extends press cycle times significantly, reducing hourly part output and increasing machine hourly rate costs per unit. Heavy nominal walls also waste raw material resin, adding unnecessary weight and cost to finished plastic components.
Molders minimize cycle delays by coring out thick sections and maintaining uniform wall dimensions.
Defect Risk
Thick sections cool unevenly, creating volumetric shrinkage differential across part geometry. Uncontrolled thermal contraction leads to surface sink marks and internal void formation in heavy wall areas.
Design Efficiency
Part designers prevent economic loss by incorporating thin nominal walls supported by structural ribs. Replacing thick solid sections with cored geometry maintains structural stiffness while reducing plastic weight. Optimized wall thickness preserves moulding productivity and keeps part unit costs competitive.