.... 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:
.... 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:
like cell phone LCD displays and keychain auto lock/alarm cases
sonic weld; it is a very specific wedge-shaped geometry which heats and collapses to produce the bonding material.
appended:
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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.
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.
Maybe that's a good sign. You'd think if it was a big problem, designs would account for and accommodate it. But, if I were in your shoes I'd be looking for a troubleshooting guide ~ one that lists the problems and explains the solutions. Failing that, I'd be looking for an industry association, a place where all the experts hang out, and get on the phone with them. Highly technical questions really need expert input.
.... 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:
called Dukane Corp. We specialize in ultrasonic and vibration welding for many different applications. Although I specialize in vibration welding, I've seen many applications that have "stuff" inside the clam shell and most weld without any problems.
mechanical energy through parts and the resulting heat generated by the mechanical movement (vertical movement in the case of ultrasonic welding) joins the parts together. Most joints use some type of energy director to "focus" the energy to a certain point in the model. Some types of joints use a shear joint which generally has the strongest mechanincal weld result.
Materials like ABS or PC weld the best although PP or vinyl or even 20% GF nylon yield good results also. You'd be surprised at how many everyday items are either ultrasonically welded or cut into pieces. Welding everything from cell phone lens bezels to baby diapers, or cutting everything from pizza to dog food.
15KHz to 50KHz although most handheld size components are probably 20KHz. Bigger stuff welds at lower frequencies and small stuff welds very quickly at
40KHz. Your exact application requirements will vary with the design of the parts, the joint design, size linear inches of the weld and the materials to be welded.
the size of the weld area. Ultrasonic welding has limits to the amount of energy you can pass through components and maintain the weld integerity. There are other alternative available, like vibration welding (my area of expertese) or hot plate welding, to name a few. The tuning process for the horns are based on a mathematical length and will take into account the location of the energy director. Internal stuff can be designed in such a way that the ultrasonic energy won't see these features.
is not intended as a sales pitch) there is a lot of useful information there. p.s. We are a big Pro/E house.http://www.dukcorp.com/us>
like cell phone LCD displays and keychain auto lock/alarm cases
easily sonic weld; it is a very specific wedge-shaped geometry which heats and collapses to produce the bonding material.
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.
Since I've been involved with ultrasonic welding (about a year), I'm astounded at what types of applications come in every single day. It's truely amazing.
In ultrasonic welding, the cost of the horns (sonotrobes) are relatively low but some of the lower "support" fixturing can get costly, depending on the design and materials used. The biggest single cost is of course, the sonic welder. I know our company offers refurbished machines at big discount. I'm sure other manufacturers do the same. I believe we even have a rental or lease option available. So that cost would be a lot lower for someone just starting off with sonic welding.
Of course the great benefit of sonic welding is, no fasteners, no glue, no gaskets, no snap fit tabs, extremely quick assembly time, permanent adhesion and possible hermetic "water tight" seals (depending on the design). This technology has been around since the early 60's and is well developed and mature.
For your future designs, please keep ultrasonic welding or other methods of welding plastic in mind. These are ultrasonic welding, vibration welding, laser welding, hot plate welding and spin welding. These are really great options for assembling plastics quickly and permanently.
This sounds like an elegant solution for packaging of some small electronics assemblies, but the obvious question, I guess, is what about serviceability?
Lee, there's the rub... You can't service anything once it's welded. The material from the two welded parts infuse with each other making it impossible to take apart; without destroying the joint.
You may be able to get some of the assemblies apart with fair results, but generally, once welded... and your done. Like I mentioned before, in small electronics, things like "sub-components" or a lens to a bezel type of weld are good choices. Main clamshell type components are probably not the best choice for this type of assembly method. Although sometimes that is exactly what is really required and then it works great !
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