Machining Polyurathene

[Oompa LumpaParticipant @oompalumpa34302]

I have a specific job I need to do and it involves making some seals from Polyurathene. I have bought a couple of lengths and today I chucked up a 22mm diameter 50mm long piece in the lathe. I tried a few different cutters and produced a very attractive pile of "snowflakes" on the bench.

I have tried HSS, Tipped tools and Tungsten Carbide. Anyone had any experience of this material? The finish produced by the tipped tool was the most acceptable but I was unable to machine to any sort of tolerance. Very much hit and miss.

TIA.

graham.

[Oompa LumpaParticipant @oompalumpa34302]

[Ian PParticipant @ianp]

Graham

What do you mean by Polyurathane?

The Polyurethane I know of is a rubbery sort of material and certainly would not produce white snowflakes. I have only 'machined' it on the lathe with Stanley knife blades.

Can you give a better description of the material?

Ian P

[JasonBModerator @jasonb]

Probably more like a PU resin which is rigid and certainly makes the confetti. Quite similar to machining Corian which is almost crumbly.

[jason udallParticipant @jasonudall57142]

Used to turn “pelathane”..soft and bendy could tie 1/4″dia rod in a knot…turned 6.3 to 2 .00 +/- .05 mm over 100 mm with 1.2 mm hole down the lot….horrid.

[Oompa LumpaParticipant @oompalumpa34302]

Posted by Ian Phillips on 14/10/2013 19:14:10:

Graham

What do you mean by Polyurathane?

The Polyurethane I know of is a rubbery sort of material and certainly would not produce white snowflakes. I have only 'machined' it on the lathe with Stanley knife blades.

Can you give a better description of the material?

Ian P

Hi Ian and thank you all for your replies so far.

"Snowflakes" is probably a bit of a dramatic term. Lots of fine crumbly white bits is probably closer to the truth. It is yellowish translucent and as described above, soft and bendy. Yes – Horrid is a good description. You could almost certainly tie a knot in a piece of 8mm diameter.
Not like Corian Jason – which I have machined with great success in the past.

How do you use the Stanley blades to turn material, they are slicing blades?

[Sub MandrelParticipant @submandrel]

Hi Jason. How did you do that? dril hole, plug with a rod, turn outer diameter?

Neil

[jason udallParticipant @jasonudall57142]

Well we used to do about 500 a month ..we?used carbide..hi rake like you would for ali..tried the stanly knife thing..mount blade segment so as to achive a shaving cut ..I used 10 degrees to vertical snap blade to 5 mm wide and clamp..
Agin horrid…great on delrin and nylon , not bad on pvdf but no chance on pelathane..any way hi rake ..lots of coolant or air blast..to stear swarf..comes off as one piece. .horrid… and threading it was misery. ..

[Ian PParticipant @ianp]

Posted by Oompa Lumpa on 14/10/2013 20:48:08:

Posted by Ian Phillips on 14/10/2013 19:14:10:

Graham

What do you mean by Polyurathane?

The Polyurethane I know of is a rubbery sort of material and certainly would not produce white snowflakes. I have only 'machined' it on the lathe with Stanley knife blades.

Can you give a better description of the material?

Ian P

Hi Ian and thank you all for your replies so far.

How do you use the Stanley blades to turn material, they are slicing blades?

'Turning' only really related to the fact that the job was rotating!

Actually what I was doing was parting off polyurethane suspension bushes to length. I just used the Stanley blade as I would a parting tool. The bus were pushed on a bit of bar and only rotated slowly.

Ian P

[BazyleParticipant @bazyle]

I recall our workshop having to turn a PTFE spike something like 3in down to a point in 18 inches. Dunked it in liquid nitrogen. Had a big sphere to go with it. I don't think it went into production. overnight in the freezer might help.

[jason udallParticipant @jasonudall57142]

Freezer didn’t help with pelathane

[jason udallParticipant @jasonudall57142]

As to dimention…traveling steady .cut to size in one pass 3 mm doc
Finish grind

[John McNamaraParticipant @johnmcnamara74883]

Hi All

Reading the above made me think of this word among others.

CONTRIVANCE
A machine or piece of equipment made with skill cleverness

**LINK**

**LINK**

Skilled people doing difficult jobs in innovative ways………..

And my two bobs on plastic…. Watch out for heat build up if you are turning to a tight tolerance, plastics expand a lot on heating. you will get undersize parts when they cool if you turn them hot.

(Unless you dipped them in liquid nitrogen…. Cool!)

Regards
John

Edited By John McNamara on 15/10/2013 14:02:07

[Nick HulmeParticipant @nickhulme30114]

Massive cutting speeds, really, really Huge!

I turn Polyurethane seals at room temperature and use cutting speeds in excess of 600 m/s for clean surfaces, the heat is removed with the material at these speeds and the stock does not significantly change dimensions,

Regards,

Nick

[Author]

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