dombanks Posted January 21, 2011 Posted January 21, 2011 right then i guess people about here have a decent enginnering background so can anyone tell me about ultasonic welding or point me in the right direction of some background info about it and its principals. ive had a bimble about the net so read the usual suspect site. if anyone near me might have one that i could maybe see i would be very greatful and will buy you a pint i've been playing with an ultrasonic cell disrupter and found i could make holes in plastics easilly and sort of stick some stuff together loosley but i think the tip is too focussed so making a hole was easy (couple that with my new 200mw laser and the lab was a happy place) whe you see the spec on one on the net it uses terms like 2000W and 20kHz. am i right in thinking it uses a wave that creates a 20khz vibration and the power is there so it can work on a larger area than a smaller power unit? i want to stick together 2 cd sized polycarbonate or perspex discs that have a thin plastic membrane in between them without using glue if i can. thanks all Quote
dombanks Posted January 21, 2011 Author Posted January 21, 2011 pretty well stuck such that they are liquid tight. imagine if each disc had a small well in it that was filled with fluid. when the two halves are stuck together the wells are sealed by the other disc, this join needs to be tight. now to add in complexity the two discs are separated by a mebrane that is say 50microns thick. this membrane needs to stay intact. its been suggested by a colaborator who knows about this kind of stuff and i trust to be right, i just would like to find out for myself about it so when we next meet i have a better understanding of the process etc. my concern is that of the video/images ive seen of the process there is always a sort of squidging of the plastics where the weld is...and this would not be good for the microfluidics on the discs, however i have read that if your careful and not harsh this can be all but eliminated. u get the fact that there this process basically melts/fusses the two elements together but i need the membrane between the to halves to stay intact. like i said, i really just need to be informed of the process, its advantages/linitations etc so next time we meet im have some sort of idea. Quote
dombanks Posted January 21, 2011 Author Posted January 21, 2011 are you taking the pish nope... just thinking out of the box as ever... as far as i can tell the complicated part will be the membrane in the middle, the rest should be ok. the problem with the membrane is it also performs other functions on the disc so has to be there. the people ive talked to seem to think they can do this and also retain optical transparency. i have ro reason to doubt them. ultasonic welding is a form of friction welding. its pretty impressive stuff. currently i use a membrane that is 25u thick but is coated with an adhesive either side so sort of posh double sided tape i want really to remove the adhesive as its not right. in doing so i need to figure out another way to stick it all together, i did wonder if in the lab i can use a spray adhesive? i also need to know about injection moulding. Quote
Westford Posted January 21, 2011 Posted January 21, 2011 Hi Dom, I am an engineer in a plastic injection moulding company, we also ultrasonic weld many parts. The subject would be too involved to discuss here, but if you pm me with details then I can help....... where abouts are you based? Westford Quote
dombanks Posted January 21, 2011 Author Posted January 21, 2011 will do westford, thanks... cant go into too much detail tho. Quote
pistonbroke Posted January 21, 2011 Posted January 21, 2011 Have you tried celotape works for me Quote
Gromit Posted January 24, 2011 Posted January 24, 2011 Could you not clamp the two discs together around the circumfrance with 2 metal/plastic rings or is that not an option. Quote
dombanks Posted January 24, 2011 Author Posted January 24, 2011 Could you not clamp the two discs together around the circumfrance with 2 metal/plastic rings or is that not an option. not really, the discs need to be sealed against eachother as both halves are covered in features that when stuck together make one complete disc. ISWIM (i have to be vague sorry) i currently use a 25u thick polyester doublesided sticky membrane but would like to change this as its not quite right. i didnt look into glues as previous work indicated there wasnt anything suitable but its something i will probably revisit if i get more funding. Quote
dombanks Posted January 24, 2011 Author Posted January 24, 2011 yes indeed. i think it might be easier. Quote
echoz Posted January 25, 2011 Posted January 25, 2011 This is like the 3rd thread you've made Dom, regarding these disc things you speak of lol. Surely you can ask whoever has asked you to make it? or is this a Dragons Den-esque invention that will make millions and save the world? Quote
dombanks Posted January 25, 2011 Author Posted January 25, 2011 i just wanted to know about ultrasonic welding as its been suggested to me as a possible method was it too much to ask? westford i will get round to PM in you just as soon as ive done with this sodding grant app Quote
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