PT ZONE: Core Operating Principles
Loss-in-Weight Overview4.3.1.2 – Elements and Operation Schematic 4.3.1.3 – Photo (upper right)PrincipleIn loss-in-weight feeding, the entire feeder, hopper and material are continuously weighed. More (+)
Loss-in-Weight Enhancements4.3.2.2 – Photo (upper right) 4.3.2.3 – Perturbation Control Art 4.3.2.4 – Refill Control Art 4.3.2.5 – Pulsing Control ArtThe basic loss-in-weight operating principle requires that special enhancements to its control scheme be made if it is to be successfully applied in practice. More (+)
MOST RECENT CONTENT: Core Operating Principles
Weigh Belt Overview
6/29/2011Plastics Technology
4.3.3.2 – Elements and Operation Schematic 4.3.3.3 – Photo (upper right)PrincipleA weigh-belt feeder primarily consists of a short belt-type conveyor that moves the material from inlet to discharge.
Weigh Belt Enhancements6/29/2011Plastics Technology
4.3.4.2 – Photo 4.3.4.3 – AutoTare Art 4.3.4.4 – Transport Lag Art 4.3.4.5 – Belt Slip ArtThe basic weigh belt operating principle requires that special enhancements to its control scheme be made if it is to be successfully applied in practice.
Weigh Meter Overview6/29/2011Plastics Technology
4.3.5.2 – Elements and Operation Schematic 4.3.5.3 – Photo 4.3.5.4 – SFM Equation w/SchematicPrincipleMostly encountered in primary resin compounding where throughputs are high, the combination of rotary valve and a gravimetric solids flow meter offers a simplified alternative to the use of a weigh-belt feeder in controlling base resin (fluff) feed rate for the proportioning of additives prior to pelletization.
Weigh Meter Enhancements6/15/2011Plastics Technology
4.3.6.2 – PhotoBypass ChannelA bypass channel allows the meter to be tared at any time during the measurement process.
Batch Blending6/15/2011Plastics Technology
Proportioning ingredients by the batch method is the simplest, oldest and most straightforward approach to formulating a plastics recipe.
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OVERVIEW:
Core Operating Principles
What are the principles underlying feeder operation, and what strategies are employed to achieve precise flow rate control and proportioning accuracy in plastics processing?
The purpose of continuous gravimetric feeding is to uniformly discharge process material at an accurately controlled weight-based rate (e.g., lb/hr or kg/min). This section introduces three operating principles typically employed in plastics processes to accomplish this purpose: Loss-in-Weight, Weigh Belt, and Weigh Meter feeding. A more detailed discussion of the issues and challenges these principles encounter is presented in the sections following this module (Focus on Material Handling, Focus on Weighing, and Focus on Control).
Also presented in this section are profiles of the two most common methods of blending multiple ingredients in plastics compounding and extrusion operations: Batch Blending and Continuous Blending.
