cleaning injection mold screws & barrels
cleaning injection mold screws & barrels
(OP)
i was curious if any of you might share how you are going about cleaning your screws and barrels. we are trying to re evaluate the way we do it at my company to try and reduce contamination. and help would be greatly appreciated. thanks






RE: cleaning injection mold screws & barrels
RE: cleaning injection mold screws & barrels
Frank M.
Tradewind Resources
http://www.tr-usa.com
RE: cleaning injection mold screws & barrels
we also just use a brass wire brush attatched to a large drill to clean out the barrel.
about the tide idea....we use radel at 740degrees F. would the tide gas off at that temp or cause any internal damage??
RE: cleaning injection mold screws & barrels
I've heard all types of methods for cleaning screws & barrels. One of the most interesting is to run kitty litter (unused, of course) through the machine. The granuals seem
If you have brass scrapers, you can get the poly off as the screw is pushed out. Using some WD-40 will usually help get some of the poly off the screw.
As for the barrel, the brass wire brush is a good idea. Possibly some copper gauze wrapped around the brush would help as well.
Hopefully, that'll help you out some.
JeffdlS
RE: cleaning injection mold screws & barrels
The best I have come across so far is to mix 1 or 2 % of water with some natural PP and purge it through. The melt will fizz, pop and bang a fair bit but you will find the the vapourised water has a great cleaning effect. It also foams the PP, this also apears to have an effect.
If after this you still have contamination it is likely that your nozzle seat or screw tip need cleaning.
In cases where the material is degrded to carbon and fussed to you screw you have little option but to strip it and clean it properly, check the damage to your seats and re-machine if required.
If you find that you spend too much time stripping and cleaning screws and barrels you may consider a furnace. It is like a fluidised bed, the sand inside is airated with super hot air, the parts are lowered in and burnt clean - the advantage is that it is non-abraisive.
Good luck
RE: cleaning injection mold screws & barrels
RE: cleaning injection mold screws & barrels
A) PS resins of low MFI are popular generic purging agents.
B) If PS is difficult to clean out, many others try PVC, allowing it to come out gelled and then add water till they see water coming out. By far, HDPE or PP are easier to clean out as they stick lesser, and do not degrade inside the barrel.
C) Proponents of chemical cleaning use Dynapurge or other suitable commercial compounds. These compounds have an initial light abrasive action. When you dead-stop the machine (5-10 minutes) and allow the chemical additive (solvent) in it to diffuse out, you either swell or dissolve the resin inside the barrel and flush it out.
E) Open cleaning with solvent and brass brushes (operator intensive)
F) Procedyne or suitable hot-sand bath (fluidized bed) can burn and clean out all material sticking to the walls and elements. However, it takes about 4 hrs to get the parts cleaned and ready for re-loading into the machine.
Note: It is imperative that the operator keep the purge agent's viscosity high enough (you should see high torque, high current draw on the extruder) to get good purging action due to enhanced shear effects. This is achieved by lowering the temperature on various zones, and running at low RPM. (20-25 on single screw and about 100 on twin)
RE: cleaning injection mold screws & barrels
We are looking for someone who can lead us to a manufacturer of Hot Sand bath units to clean nozzles and tips
RE: cleaning injection mold screws & barrels
RE: cleaning injection mold screws & barrels
RE: cleaning injection mold screws & barrels
RE: cleaning injection mold screws & barrels
Now when you say:
we are trying to re evaluate the way we do it at my company to try and reduce contamination.
It seems to me there is contamination even after the barrel/screw have been pulled and cleaned, if so we might be dealing another issues for example:
*Running PVC if the melt temperature is too high, molded parts will show not only burning but also “black specs.”
*Polysulfone mixed with liquid dye colors that are not a resin grade comparable will show as contamination.
*A worn out screw and barrel with all kinds of deep drag marks, collecting a small amount of molted plastic, and then at some point and time now carbonized breaking lose from the barrel during the run.
Could there be any resemblance?
Best regards.
RE: cleaning injection mold screws & barrels