INJECTION MOLDING PROBLEM SOLVING REPORT
LET'S ASSUME THE FOLLOWING PROBLEM - WE ARE EXPERIENCING BURNING
ON THE PLASTIC PARTS. OUR MATERIAL IS GLASS FILLED ABS. TOOLING
IS A THREE PLATE MOLD, ONE EDGE GATE PER CAVITY, WITH A SMALL
SHOT SIZE IN THE MACHINE.
THIS PROBLEM CAN BE CAUSED BY THE FOLLOWING CONDITIONS:
- THE INJECTION SPEED MAY BE TOO FAST, ADJUST THE FLOW CONTROL VALVE.
A fast injection speed will cause a faster plastic flow rate which
will result in greater compression of air in the cavity. A greater
compression of air in the cavity will cause an air temperature
greater than the plastic ignition temperature which may result
in a burning condition.
- THE 1ST STAGE PRESSURE MAY BE TOO HIGH. (80%)
A high 1st stage pressure will cause a faster plastic flow rate
- THE NOZZLE TEMPERATURE MAY BE TOO HIGH. (66%)
A high nozzle will also cause a higher plastic temperature.
- THE BACK PRESSURE / BARREL TEMPERATURE MAY BE TOO HIGH. (63%)
Again, a higher back pressure will lead to a higher plastic temp.
and a lower plastic viscosity as noted above.
- THE CLAMP FORCE MAY BE TOO HIGH. (50%)
A high clamp force will lead to less air flow between the parting
lines and that will produce the greater compression of air in
(%) indicates probability that this is the problem.
+ correcting this condition may decrease cycle time.
- correcting this condition may decrease cycle time
[Return to Processing Archive]
THE PLASCO NETWORK is published by PLASCO INC. information contained
in the newsletter has been taken from sources which we deem reliable.
we cannot assure its accuracy. any opinions expressed reflect
our judgment and are subject to change. all rights reserved. reproduction
or copying in any form, requires written permission from PLASCO
INC. M. LODICO -editor