The Gravimetric Feeding Triangle
All gravimetric feeders, regardless of type or operating principle, must meet three core requirements, here represented as the three sides of a triangle.
- Material Handling: Condition the material to minimize density variation (as required), and then produce a volumetrically uniform discharge stream
- Weighing: Continuously perform accurate, high-resolution weight measurements to form the basis for subsequent control actions
- Control: Continually determine and execute appropriate control actions to achieve or maintain the required gravimetric discharge rate
Each side of the feeding triangle presents its own unique array of challenges, and each dynamically interacts with the other two. Successfully producing an accurate and consistent discharge rate demands a careful blend and balancing of these three important aspects of gravimetric feeding.
Before focusing more closely on each leg of the feeding triangle (Focus on Material Handling, Focus on Weighing, and Focus on Control), the following section provides a brief introduction to the operating principles behind the most commonly employed approaches to gravimetric feeding in plastics processing (Core Operating Principles).