Optimizing Mechanical Restraint Forces in Non-Rigid Polymer Metrology under ISO 5459 Guidelines
Balancing restraint forces under ISO 5459 ensures accurate datum seating without distorting non-rigid polymer part features during coordinate metrology.
ABS
Meaning
Terpolymer resins consisting of butadiene rubber dispersed in a styrene-acrylonitrile matrix provide high impact resistance and structural rigidity. Known widely by its acronym, abs is processed across a temperature range of 220 to 260 degrees Celsius. High hygroscopy requires desiccant drying to below 0.02 percent moisture before processing to avoid splay marks.
Resin Behaviour
Melt flow behaviour is highly non-Newtonian, meaning shear rate influences viscosity more than temperature changes do. Processing must balance melt temperature and injection speed to control molded stresses. Slower injection rates can cause premature freezing, whereas excessive shear heats the melt to degradation.
Defect Prevention
Molded parts can develop cosmetic defects or structural failures if the process parameters deviate. Inadequate packing pressure during the holding phase leads to sink marks or void formation in thick sections. High residual stresses from uneven cooling in the mold cause warpage during ejection.
Selecting the correct mold temperature, usually between 50 and 80 degrees Celsius, ensures an optimal balance of cycle time and part finish.
Material Substitution
Selecting between virgin resins and regrind mixtures is a primary cost driver in high-volume production. Incorporating more than twenty percent regrind often decreases mechanical strength and impacts color consistency. Recycled polymer yields lower tensile properties because the heat history degrades the butadiene rubber phase.
Molders must test melt flow indices to confirm the stability of the blend.