Welding plastic



All welding does not require melting the material. Copper to copper can be done with just pressure. And then there is forge welding. But I agree, it isn't what I normally think of as welding. From Wiki
Forge welding is a welding process of heating two or more pieces of metal and then hammering them together. The process is one of the simplest methods of joining metals and has been used since ancient times. Forge welding is versatile, being able to join a host of similar and dissimilar metals. With the invention of electrical and gas welding methods during the Industrial Revolution, forge welding has been largely replaced.
Forge welding between similar materials is caused by solid-state diffusion. This results in a weld that consists of only the welded materials without any fillers or bridging materials.
Forge welding between dissimilar materials is caused by the formation of a lower melting temperature eutectic between the materials. Due to this the weld is often stronger than the individual metals.
The temperature required to forge weld is typically 50 to 90 percent of the melting temperature. Steel welds at a lower temperature than iron. The metal may take on a glossy or wet appearance at the welding temperature. Care must be taken to avoid overheating the metal to the point that it gives off sparks from rapid oxidation (burning).
Dan
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Can any plastic be welded? Any thermoplastic, that is?
Given that the filler has to be the same material as the "stock", is it hard to identify it?
Thanks, Bob
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I think you had the idea - thermo - might be the issue.
Some are not by a long shot.
Martin
Bob Engelhardt wrote:

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This might help:
http://www.boedeker.com/burntest.htmhttp://www.boedeker.com/burn test.htm
I have another link, I think at work, that includes whether if floats or not. It really works.
Ken
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Ken Moffett wrote:

Make that: http://www.boedeker.com/burntest.htm
Thanks - read & bookmarked.

The more, the better. In the past I've been frustrated using plastics identifiers. One I remember used a question-answer decision tree, usually ending with "Sorry, there are no plastics that fit those answers". Gaaa!!
Bob
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I couldn't find it yesterday. Buried in a list of links. I'll keep looking.
I just got to get organized....next week!
Ken
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^^^^^^^^^^^^^^^^^^^^ For me, right now, that's the $64 question. My HF welder came with a small bundle of filler rod, in three different colors--each color is a different plastic, but not a clue as to what each one is. When I approach a repair job, I won't usually know what plastic it is either. So what do I do? Try one thing after another until I either ruin the job or find the right filler by trial and error?
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says...

"Late model" plastics may have a recycle number moulded into them- check the "out-of-sight" areas to see if it's there. Wiki has a listing of the numbers and what the materials are.
You may be able to "reverse-engineer" by checking Wikipedia's recyle number listing, and seeing if any of the characteristics of the plastic you have match up. Not quite as easy as a spark test, but might work...
--
Tin Lizzie
"Elephant: A mouse built to government specifications."-Lazarus Long
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Leo Lichtman wrote:

White - ABS Green - Polypropylene Gray - Polyvinyl Chloride
BUT you can buy filler rods from other sources as well.
http://www.tempatron.co.uk/weld_rods.htm
http://www.sailing-starting-over.com/plastic-welding.html
http://www.urethanesupply.com/storerods.php
http://www.articlesbase.com/tools-and-equipment-articles /identifying-plastics-for-plastic-welding-815080.html
--
Steve W.

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Bob Engelhardt wrote:

I was all keen to get a plastic welder until I read the replies & remembered the futility of my trying to identify plastics in the past. Now I think that plastic welding may be great in an industrial setting where the material is known precisely, but not so much for the hobbiest.
Thanks for helping me avoid that frustration, Bob
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