How to fix mechanical problems with your loss-in-weight feeder — Part I
A loss-in-weight feeder can accurately meter powders, granules, and pellets in several industries, including foods, chemicals, pharmaceuticals, and plastics. But if the feeder hasn't been installed correctly, mechanical problems can create slight upsets or artificial forces that disturb the weight readings and affect the feedrate. Part I of this two-part article explains how a loss-in-weight feeder operates, how to recognize symptoms of mechanical problems, and how to run feeder tests. Part II, which will appear in the January 1999 issue, discusses how to find and fm mechanical problems.
Even with the most advanced control algorithms and material handling components, a loss-in-weight [LIW] feeder can't perform reliably if its weighing mechanism doesn't function as intended. This problem typically stems from a poor feeder installation. [Author's note: While this article concentrates on finding and fixing mechanical problems with continuous LIW feeders, many of the principles also apply to batching LIW feeders.]