Consistent quality and quantity of product
from extrusion machineries depend on nos. of refinement equipments
and limitation of plant.
First three problems are basic and it
has bearing on product specification and application. This paper describe
process related and operational related problems in
| TROUBLE SHOOTING
GUIDE FOR GENERAL EXTRUSION |
| PROBLEM |
POSSIBLE CAUSES |
SOLUTIONS |
| NO EXTRUDER OUTPUT |
Hopper empty. Hopper feed
throat bridge Complete screw bridge. |
Fill hopper. Cool hopper feed
throat locket. Clean feed throat coolent Channel. Do not use hopper
dryer. Cool rear barrel heat zone to 150 °C or less Internal screw
cooling first 4-5 turns of feed section. Cool hopper feed throat jacket.
Calibrate rear barrel heat zone controller. |
| EXCESSIVE EXTRUDER DRIVE
POWER REQUIREMENT |
Rear barrel heat zone too
low. Barrel heat zone over screw transition zone too low. Melt temp.
too low. |
Increase rear barrel temperature
Increase temperature of barrel heat zone over screw transition zone
Increase barrel temperature. Increase screw rpm to increase shear
working. |
| SURGING |
Screw design Extruder drive variation
Improper temperature Gradient (barrel) Improper water circulation
in feed section. (Grooved feed barrel) improper mixing of end trim
|
Select screw with Metering zone Higher
compression ration. More shallow metering depth. Feed zone atleast
25% of length. Gradual transition. Check drive performance. Increase
barrel feed zone & Compression zone temperature Reduce screw speed.
Clean water circulation path with anti-sealing solution. Increase
water flow rate. Check water temp. (inlet & outlet) Adjust and
trim feeding system. Minimise film shiffting. Check quantity of end
trim. |
|
Courtesy: Mr. P.M. Jariwala, Kolsite Industries
|