Extrusion Minimum Runs Measured in Tonnes Rather than Pieces
Extrusion runs are quoted in tonnes because start-up scrap, thermal equilibration, and bulk resin compounding operate as continuous mass processes.
Masterbatch Let-down Ratio
Meaning
Quantitative relationship between the amount of concentrated additive and the virgin resin used in a polymer blend. This ratio determines the final color, UV resistance or flame retardancy of the molded part. Expressed as a percentage or a parts-per-hundred value, the masterbatch let-down ratio is a critical setting for both cost control and functional performance.
Color Consistency
Variations in the dosing level lead to visible differences between production batches. When the masterbatch let-down ratio is too low, the part may lack opacity or fail to meet the specific shade required by the brand owner. Accurate calibration of the dosing equipment is the only way to ensure color repeatability.
Functional Loading
Additive efficiency depends on reaching a minimum concentration within the final part. For example, an antioxidant will only prevent degradation if the masterbatch let-down ratio provides enough active molecules to neutralize free radicals. If the ratio is exceeded, the excess additive can sometimes migrate to the surface and cause blooming or adhesion issues.
Economic Impact
Over-dosing leads to unnecessary manufacturing costs because masterbatch is significantly more expensive than base resin. Small adjustments to the masterbatch let-down ratio can result in large savings over a year of high volume production. Precise control allows the moulder to maintain quality while minimizing the consumption of premium concentrates.