Polypropylene Copolymer versus Homopolymer Impact Resistance
Impact copolymers deliver superior notched and subzero impact resistance over homopolymers by incorporating a dispersed ethylene-propylene rubber phase.
Volumetric Yield
Meaning
Ratio of the number of components produced to the weight of the raw material used defines the economic efficiency of a resin. Calculating volumetric yield involves dividing the volume of a single part by the density of the polymer to determine the theoretical output per unit mass. This measurement allows for a direct comparison between materials with different densities, such as talc filled and virgin grades.
The value is used during the quoting stage to ensure that the material cost per part is accurate. It stops being a reliable indicator if the scrap rates are high or if the part dimensions vary during the run.
Density Calculation
Determination of the specific gravity of the resin is the primary factor in estimating the final production volume. Because volumetric yield is higher for materials with a lower density, polyolefins often provide more parts per ton than engineering plastics. Moulders must account for the density of the base resin and any fillers or additives used.
Accurate weighing of the input and output is necessary for process control.
Sourcing Advantage
Procurement of a lightweight resin can reduce the total material expense of a project even if the price per kilogram is higher. Since parts are sold as units, a high volumetric yield translates directly into a lower part cost. Procurement teams use this metric to evaluate competing supplier quotes.
Strategic sourcing focuses on the cost of filling the mould cavity rather than the cost of the raw weight.
Part Costing
Integration of the yield into the financial model helps maintain the profit margins of a moulding business. If the volumetric yield is not accounted for, a project may appear more profitable than it actually is. Consistent monitoring of the material usage identifies hidden costs in the production cycle.
Accurate data leads to better pricing strategies.