(171b) Developing a Loss-in-Weight Feeder Design Space Based on Performance and Material Properties

Abstract

Loss-in-weight
feeders play a vital role in controlling content uniformity in continuous
manufacturing.  If, in a brief period of time, the feed rate of one
ingredient changes with respect to the others, the change in concentration of
the process stream can propagate throughout the system.  Understanding how
the feeder and the material behave is vital. Powder properties, such as density
and cohesion, can cause large variability in the flow rate of ingredients fed
from powder feeders. Also, one needs to understand the operational ranges of
the feeder, i.e. percent motor power, which coincides directly with screw speed.
 Knowing an ideal range of operation and correlating powder properties to
process performance can lead to determining the design space of the feeder accurately,
and to faster optimization of feeder performance, which also saves money and
material.  In this work, a K-Tron KT-20 pharmaceutical loss-in-weight
feeder has been evaluated with four common screw types (coarse auger, fine
auger, coarse concave, fine concave), for various pharmaceutical (Avicel, Lactose Monohydrate, Magnesium Stearate,
Acetaminophen, Prosolv, etc.) and catalytic powders, at
multiple feed rates.