Meaning
The percentage of masterbatch mixed into the virgin resin determines the final concentration of additives or pigments in a plastic part. Letdown ratio is typically expressed as a ratio such as twenty to one or as a percentage like two percent. Accuracy in this value is necessary to ensure that the part has the correct color and protection levels.
Dosing Control
Consistent addition of the concentrate is required to maintain the quality of the production run. If the letdown ratio varies during the day, the color of the parts will drift and the physical properties might fluctuate. Using high quality feeders and properly sized masterbatch pellets helps to keep this ratio steady throughout the entire process.
Cost Optimization
Finding the minimum effective amount of additive helps to keep the material expenses low. A letdown ratio that is too high wastes expensive chemicals, while one that is too low can lead to part failure or poor appearance. Moulders test different levels to find the point where the part meets all specifications without using more masterbatch than is necessary.
Product Performance
Accuracy of the mix affects everything from UV resistance to the flame retardancy of the final product. When the letdown ratio is calculated, it must account for the concentration of the active ingredients in the masterbatch. A well defined ratio ensures that every part produced has the same level of performance, which is necessary for meeting regulatory standards and customer expectations.
Small errors in the addition rate can lead to large batches of rejected material, so precise measurement and thorough mixing are the foundations of a successful moulding operation.
