posted 06-20-2001 10:32 PM
How do I know if my screw and barrel are straight and in alignment without pulling the screw and have an alienment done? In other words, what are the problems that can arise should the machine be out of alienment or the screw or barrel be bent that would tip me off I have a problem.
posted 06-21-2001 09:01 AM
Look at the die head. Does it move around slightly?
Do your heaters try to rotate around the barrel over time?
Can you get the screw in and out of the barrel easily?
Most problems can be seen in screw wear patterns which will require a screw pull.
In a single screw extruder, screw to barrel clearance is very important. Getting a tight fit and keeping it requires good alignment. Without good alignment a whole list of bad things can happen.
If you are not sure about the alignment of your extruder, pay the price to get it done right. Find someone with a laser alignment tools. It could cost a lot more later on if you don't have it done. I think the larger the extruder, the more important it is to have and alignment performed.
posted 06-21-2001 02:03 PM
THE FACT THAT YOU GET MOVEMENT SIDE TO SIDE AT THE HEAD IS A TIP OFF THAT YOU HAVE MAJOR ALIGNMENT PROBLEMS OR EXTREME WEAR AT THE HEAD END OF THE BARREL AND SCREW. ALIGNMENT CAN CAUSE THIS WEAR. THE NRM EXTRUDERS WE HAVE IN PLANT HAVE A SET OF BLOCKS ON A SUPPORT YOKE AT THE HEAD END. THIS IS WHERE MINOR ADJUSTMENTS ARE DONE. YOU CAN TAKE THE COVERS OFF AND LOOK TO SEE IF THE BARREL IS SETTING ON THESE BLOCKS, POSSIBLY THERE MAY BE SHIMS THAT HAVE FALLEN OUT. IF YOU HAVE RECIENTLY MOVED AN EXTRUDER YOU SHOULD HAVE IT BARREL SCOPED TO REALIGN DUE TO BASE CHANGES. WE HAVE A LARGE NUMBER OF EXTRUDERS AND FOUND IT COST EFFECTIVE TO PURCHASE A BARREL SCOPE AND TRAIN OUR MAINTENANCE PEOPLE IN IT'S USE. WHEN WE CHANGE A FEED BOX OR A BARREL WE SCOPE IT. IT IS NOT THAT DIFFICULT JUST TIME CONSUMING AND REQUIRES SOME PATICENCE. HOPE THIS HELPS
quote:Originally posted by jesperpetersen: How do I know if my screw and barrel are straight and in alignment without pulling the screw and have an alienment done? In other words, what are the problems that can arise should the machine be out of alienment or the screw or barrel be bent that would tip me off I have a problem.
Jesper
That was two questions. The answer to the first is let the screw run dry and turn at slow RPM - If you hear a consytant rubbing when it hits the same spot in the 360 degree rotation, you have a problem.
Question two, the problems that can arise are;
Look for contaminatian in the form of metal chips in your product.
Radiopaque extrudate. (Just kidding here, but metal contaminants would show up under X-Ray.)
My suggestion would be to check to see that the screw goes into the barrel and seats with a minimum of hand pressure. Any resistance indicates a problem. Do this check when you pull the screw for periodic inspection. You do pull the screw on occasion don't you
posted 06-20-2001 10:32 PM
(Just kidding here, but metal contaminants would show up under X-Ray.)
Do this check when you pull the screw for periodic inspection. You do pull the screw on occasion don't you 