Cutting thin walled plastic tube

[alansimpson]

I have lengths 1200 of 44 mm dia 0.5 mm w.t. PET tubes I need to cut into 300 mm lengths. 300 in total.
I have tried various cutting and edge cleaning methods (hacksaw, sharp blade, high speed circular saw) and and haven't got clean cuts.
Tube manufacturers usually cut straight off extruder and couldn't give much advice.

Cant find recommend cutting method or speed data.

Can anybody make some recommendations?

Thanks

 

[unclesyd]

Here is just one of many automatic tube cutters available.
There are other machines that are not automatic out there also.
If this is a one off job there are several job shops that will do the cutting on a small lot basis in house.

http://www.automaticwirecutter.com/About_Us.asp

Google around.

tube cutting +plastic

 

[btrueblood]

Is the problem that the edge is not straight, or that you are getting burrs or non-smooth edges of the cut.

Sounds like the latter. Have you tried an abrasive cutoff wheel, with or without coolant?

 

[alansimpson]

The problem is burrs. I have tried diamond abrasive disk. No luck.

 

[SincoTC]

I think that the biggest problem you've got, is that the wall thickness is only half a millimeter, so so with its 44mm diameter, even holding it without crushing or distorting it is not easy and you would need very low force cutting methods to have any chance.

If I had 300 to do, I'd make a simple tool comprising a fairly close fitting plug, a bit longer than the finished length and mounted with one end screwed to a block on the LH end of a bench; so that the plug is horizontal and pointing along the bench, arrange an arm to carry a scalpel blade or similar at the right length. As you hardly need any travel, just ensure that the blade arm is wide enough to be rigid laterally so that the cut doesn't wander but thin enough so you can flex it to apply the cut (like a steel rule). Now slide the tube onto the plug and hold it against the block while you turn it with your left hand and pull the blade down with the other hand until it cuts through, slide that piece off the plug and repeat the process. The tool would be quite simple to make and could easily be made of wood, just make sure the tube turns easily on the plug without too much slack.


Trevor Clarke. (R & D) Scientific Instruments.Somerset. UK

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[unclesyd]

A lot of the plastic tube cutting machines actually flatten the tube prior to cutting. The flattening is an essential part of the cutting process.

 

[tanbui]

To cut thin plastic tubing, considering these followings:
1. Bushing with tight tolerant to constrain against flattening
2. Using Knife, very sharp recommended
3. Very high cutting speed. For this size, 60ft/s cutting through speed is OK. This is from experience, theory far to be developed!

 

[ornerynorsk]

If you've got a gazillion of these things to cut, it would be worth investing into a high-end cut off die. Either a 2 knife style like Vogel makes for metallic tubing or an orbital "wobble" type of die that is basically an oversize outer ring die that is driven off center to initiate the cut and orbited through one revolution off-axis to produce a continuous external shear towards the inner die (mandrel). Neither one of these options is going to be inexpensive.

 

[Jabberwocky]

I'm no expert in this field, but could you fill the tubes with a fluid to hold their shape while the cut takes place? Similar to what is done when bending around a mandrel to keep the cross-section constant?

Otherwise maybe something like a waterjet that's not supposed to introduce much force into the part - don't know about the divergence angle of the spray...

maybe even a wire EDM if it won't cause melting issues?