Not exactly a ProE post....

..... but I don't post to any newsgroups or boards to do with
manufacturing.

Does anyone know much about ultrasonic welding of plastic parts? Is it
possible to weld two halves of an enclosure closed with several
internal components sandwiched between these two halves? They would be
completely contained within the two halves, nothing protruding beyond
the perimeter of the two halves being welded. I want a waterproof seal
around the weld. My concern is whether the other internal stuff might
absorb the energy of the weld. They would have to touch the internal
surface of the two parts being welded, otherwise they would rattle
around inside.

 

.... but I don't post to any newsgroups or boards to do with
manufacturing.

Does anyone know much about ultrasonic welding of plastic parts? Is it
possible to weld two halves of an enclosure closed with several
internal components sandwiched between these two halves? They would be
completely contained within the two halves, nothing protruding beyond
the perimeter of the two halves being welded. I want a waterproof seal
around the weld. My concern is whether the other internal stuff might
absorb the energy of the weld. They would have to touch the internal
surface of the two parts being welded, otherwise they would rattle
around inside.

I don't believe the sandwiched stuff would absorb the energy because
1.. sonic welding is extremely localized and is used mainly on small units like cell phone LCD displays and keychain auto lock/alarm cases
2.. parts made for sonic welding are designed with features that will easily sonic weld; it is a very specific wedge-shaped geometry which heats and collapses to produce the bonding material.
This is a good general description with some detailed references appended:
http://en.wikipedia.org/wiki/Ultrasonic_welding

David Janes

 

.... but I don't post to any newsgroups or boards to do with
manufacturing.

Does anyone know much about ultrasonic welding of plastic parts? Is it
possible to weld two halves of an enclosure closed with several
internal components sandwiched between these two halves? They would be
completely contained within the two halves, nothing protruding beyond
the perimeter of the two halves being welded. I want a waterproof seal
around the weld. My concern is whether the other internal stuff might
absorb the energy of the weld. They would have to touch the internal
surface of the two parts being welded, otherwise they would rattle
around inside.

I don't believe the sandwiched stuff would absorb the energy because
1.. sonic welding is extremely localized and is used mainly on small units like cell phone LCD displays and keychain auto lock/alarm cases
2.. parts made for sonic welding are designed with features that will easily sonic weld; it is a very specific wedge-shaped geometry which heats and collapses to produce the bonding material.
This is a good general description with some detailed references appended:
http://en.wikipedia.org/wiki/Ultrasonic_welding

David Janes

 

Thanks Dave. The thing I'm looking at welding is about the size of a
cell phone in fact a bit smaller. I've read a tonne of online stuff
about the subject and everything has been about the design of the part
of your component which melts and welds. There's lots of details out
there, but nothing about the rest of the welded components and what
effect they have on the welding process.

 

Thanks for this info, Bob. Unfortunately I've pushed this barrow as
far as it will go. The manufacturers for our client aren't willing to
try it as they're not experienced........ so we'll be using dirty
great screws and gaskets. Dumb.

 

Yes, it seems like a no-brainer to me, but I'm not the one who has to
implement it. I think what we're going to do is when we get some off-
tool parts we might try and machine around the part line to leave an
energy director and experiment with welding them.

 

This sounds like an elegant solution for packaging of some small
electronics
assemblies, but the obvious question, I guess, is what about
serviceability?

Lee Braden