Endcap/Barrel Removal

[brstuczko]

Hi All,

We are having difficulties removing endcaps and barrels on our molding machines. I haven't been able to find a best practice for this task so I wanted to ask the forum! We apply anti-seize prior to installation and torque to the manufacturer specs for both the endcap and barrel. Some of our injection units have probably been running for about 3 to 4 years without being disassembled and these are typically the ones we have the most trouble with.

Is it best to perform the removal while the injection unit still has the heats on? I am considering purchasing an impact wrench for just the removal portion and replacing the cap screws with new ones when re-installing with a torque wrench. The endcap cap screws are M20 and the barrel cap screws are M24.

We are looking to create a yearly TPM program of injection unit wear measurements and inspections, however with the lack of proper tools and amount of time required to perform this job this TPM program is just a dream for now.

Thanks guys!

[rickbatey]

Purge press empty then I prefer to Chrystal PS through unit. It's easy to peel off after cooling.
Now remove while hot. It'll be easier. Replace hot as well. I put anti-seize around end cap to barrel mating surfaces. Makes them easier on next tear down. DO not over torque bolts as that can cause end of barrel to collapse in and be too tight around screw tip. Replace bolts each time due to heat/torque. Liberal amounts of anti-seize on bolts and start tightening in a star or criss cross pattern. Tighten in at least three steps to torque settings, BUT only after reaching operating/tear down temp. Take your time cuz you only want to do this once!
Rick.

[ArikB]

I would just like to point out that if you are going 3-4 years without looking at your screw and barrel conditions you probably nailed it when you said those are the ones you have the most problems with.

Do you, yourself, apply the anti-seize? If not, I would consider the possibility that maybe you aren't putting anti seize on as often as you think. I get on some of my maintenance guys for trying to sell me that crap. Its pretty easy to tell when its been applied (although after 3 or 4 years maybe not so much)

Check the procedure your guys are using when tightening the bolts. I usually grab four bolts 90 degrees offset from each other and the incrementally work around the adapter clockwise. If you put the adapter in a big enough bind you can also bind the bolts.

One last thing that I hate having to suggest is that maybe the wrong bolts were put in. Just this year we had a new guy replace a bolt with a different thread and cross threaded that bolt all the way in. (That employee is now a PM tech)