Letter 39089 Joining Polypropylene Sheet [New Zealand]  January 19, 2006 Hi, I operate a wind tunnel in New Zealand, We have just relaid our moat(which is our water coolant supply for a 950 HP Detroit) the PP is 1 mm thick and if you could tell me how to join it together it would be much appreciated,we were given some Butyl double sided tape to use but it did not hold, regards Ron Morgan bodyflying - Rotorua, New Zealand First of two simultaneous responses -- January 20, 2006 Hi Ron, Yucks, you were given some wrong info ... tape ????? Hell, no. To join PP sheet you'd need to weld it. Sorry. There's a good Company called Thermoplastic Engineering in N.Z. ... give them a call. If you have lots and lots of welding to do, ah, then try & get a welding gun WITH instructions (Over here it's LARAMY a U.S. Company) ...STOP ... I then re-read your message. You are only using an ultra thin l mm thick PP. Oh dear. This would really present problems due to heat distortion with such a thin laminate even to a fully experienced professional. H'mm. What about overlapping by an inch or so and then 'soldering' in on, ie. using an iron (?) ... so approach Thermoplastic Engineering. ... who might well proffer better advice. Freeman Newton - White Rock, B.C. Canada   Second of two simultaneous responses -- January 22, 2006 You have to hot weld it using parent rod of polypro and appropriate hot air guns (for very critical parts some recommend inert gas instead of air). Any good plastic fabricator can help you. Good luck. Guillermo Marrufo Monterrey, NL, Mexico First of two simultaneous responses -- January 23, 2006 The most effective method of joining polypropylene sheet is to weld it. Do a search on plastic or polypropylene welding for more info. John Martin - Wales Second of two simultaneous responses -- January 23, 2006 Hi Guillermo, Re an inert gas for welding, the problems in Ye Olden Days was with people using an ordinary compressor and ultra minute traces of oil or condensation would result in some poor welding. One Company used to use silica gel to get a 'clean' air. A low output compressor is the answer ... this idea came from Germany where, as you know, PVC was invented and where, initially the best welders came from. With Pe, the same family as PP, it seems that the surface builds up an ultra thin oxide layer ... I would get a poor result on welding a thin but clean l/8" laminate BUT if that surface were scraped beforehand, ah, the weld appeared good to an amateur like me. This is a REAL problem with l/16" PP but the given l mm = a lousy l/32" !!!! Yucks ! Freeman Newton - White Rock, B.C. Canada   January 24, 2006 Thanks to the two reply's , you have both been a lot of help ,I have got onto a company that think they should be able to weld it. Regards, Ron Morgan - Rotorua , New Zealand February 1, 2006 Sorry friends,,but for materials that thin , you need an ultrasonic welder.. [I have one] I have laramy - wegener - kamweld - liesters and god knows how many others...I've never seen a heat welder work on material .039 thick Ron Landrette - Bristol, CT, USA Thanks, Ron. I know Ron, and Ron would know! Ted Mooney, P.E.  finishing.com Brick, NJ

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