Focus on Weighing

Key to gravimetric feeding, weight measurement provides the means to "close the loop" on feed rate control. This section details the unique challenges faced in precision weighing in the process environment, and profiles the technologies and application considerations surrounding this crucially important contributor to feeder performance.

The second leg of the gravimetric feeding triangle, weighing, refers to a feeder’s on-board measurement of this crucially important variable, essential to the accurate determination and control of gravimetric feed rate.

This section begins with the core challenges faced in the weighing operation. Next, the three most prevalent current technologies in weighing are introduced: the vibrating wire, the strain gauge, and the linear variable differential transformer, or LVDT.

And in the last three sections, weighing issues are detailed for each type of feeder operating principle (loss-in-weight, weigh belt  and weigh meter) commonly employed in plastics processing.