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Non-sticking coating for welding blade

 

Hi,

We are providing both thin film and thick film coating services. One of our customer has sticking problems with his PE plastic film welding blade. He has tried PTFE coating which improves but can not last long enough. The blade in made of Copper alloy. I would like to know if any thin film helps in reducing the sticking phenomenon?

Thanks in advance and best regards,

Ning Yang
- Hsinchu, Taiwan

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Hi Yang,

On the face of it what you are doing is apparently correct.

However, I am, to use an expression, a Doubting Thomas! You mention PTFE ... and I say to myself, really? Is he talking about a true PTFE or another of the 4 or so 'teflons' masquerading as Teflon rather than, say, FEP teflon or Halar. I was told (centuries ago) that PTFE was a sintered material and had to be made under high pressure, was 100 degrees better in heat applications than other 'fluorocarbons' but totally and utterly unweldable, hence unfuseable.

May HIS method of application is at fault, not yours?

I know of no material better in non-adhesion than Teflon.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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It's probably what you would call a thick film, but chromium plating has been the traditional standard for wear resistant non-stick applications.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
 

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I have checked it again with the customer. Mr. Newton was right---actually it was the Teflon coating. According to my limited knowledge about Teflon, it seems that there are various kind of Teflons. How can I find one which could last long under 300 °C?

Best regards,

Ning Yang,
- Hsinchu, Taiwan

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Hi again, Jang

300 C? Ow. I don't that even the true PTFE teflon would go that high.

As said, I'm a Doubting Thomas, meaning that when people say something to me, I take it with a big grain of salt.

If your customer is 'fusing' some plastic ... one assumes a Polyethylene but maybe a Polypropylene, surely, SURELY 300 degrees is far too high.

To check on the teflons, use the internet. Go, perhaps, to Dupont and see what they have to offer.

Cheers !

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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You might want to try some of the new carbon coatings such as the diamond-like carbon (DLC) which has a very low surface energy and very low coefficient of friction.

Donald M. Mattox
Society of Vacuum Coaters
Albuquerque, New Mexico  

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The application you are talking about it can be solved with a Teflon coating, but we must to take care with:

- The blade is made in copper. It is a problem. To cure the Teflon coating it must to achieve the 375°C, at this temp. the copper becomes oxidized and the adhesion of the coating will fail.
- Change the material into aluminium, it is faster to warm up and you'll have better adhesion.
- Reduce the operation temperature to 260°- 280°C the welding will take few seconds more, but the live of the coating will increase dramatically.
-Choose the right coating. I'll suggest you a PFA coating, or if you find it a mix of PTFE, PFA and any ceramic filler.

You'd better contact a Teflon coater.

Good luck,

Jordi Pujol
- Barcelona, Spain