NH4000 atc door closes very hard

[dwatsonftech]

ATC door just before closing all the way then reverses for just an instant and then closes all the way with a hard slam. Just started happening recently.

Any ideas?

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[chippslinger]

We had the same problem with our NH4000 and let it go till we ended up having to replace linear guides, pneumatic cylinder, linear rail, and all proximity switches. What the problem is is the internal buffer in the cylinder has failed and you cannot rebuild it. You will need to get a new cylinder. If you let it go it will damage your linear guide bearings and then the rail causing the door to droop and then start to chop up your proximity switches which will give you alarms that the door is not closed or not open. I know this from running our machine balls to the wall and owner not wanting to stop and address situation till machine just stopped and I rebuilt whole ATC door assembly. Fix it now before more problems arise.

[WallyL7]

Very common problem with those machines. Need a new cylinder like chippslinger said.

[dwatsonftech]

Many thanks to all.

New cylinder to be ordered.

[coolhand03]

not sure if anyone is still following this thread, but we had the exact same problem with our NH5000 DCG. we payed over $1600 for a new cylinder from Mori. the cylinder is available from SMC for $376.(i was told 8 weeks lead time, mori had it in stock) we installed the new cylinder and the door opens/closes as smooth as can be. i just wanted to share the fact that these cylinders ARE completly rebuildable. we disassembled the old cylinder after we put the new one in. it comes apart with no trouble. the part that fails inside is the nylon wear band on the piston. once air gets past it and blows on both sides, the cylinder fights itself. thats what causes the jerking at the end of the stroke. i hope this helps someone.

[SurfcamProgrammer]

Hello,

I am having the same problem with our NH4000. By any chance does anyone know the SMC part number for the replacement cylinder? I've been searching for it without success.

Thanks!

[KPG9198]

You can sometimes adjust this out of the door with the needle valves on the cylinder, it may also be some debris caught in the detent (small straight slotted screw next to needle valve)
the detent is what cushions the cylinder in the last 1/2 " of the stroke