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| plastic welding http://forum.triumphdolomite.co.uk/viewtopic.php?t=36756 |
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| Author: | new to this [ Mon Jun 21, 2021 12:40 pm ] |
| Post subject: | plastic welding |
Has any one tried plastic welding,is the weak point the joint where youve welded ? Dave |
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| Author: | marshman [ Mon Jun 21, 2021 2:28 pm ] |
| Post subject: | Re: plastic welding |
Can be depends what techniques you are using, how well you do it and the type of plastic. Remember only thermal plastics can be welded, thermoset types cannot. We used to Ultrasonic weld ABS parts together where I used to work. Basically the two parts are vibrated together and heat is generated between the two surfaces which melts the plastic together - one part usually has a small sacrificial peak which melts to fill the joint. In those cases the joint was stronger than the surrounding case but only I suspect because the joint was thicker. On another product we "solvent welded" parts together using granules of raw plastic "melted" or "dissolved" in a 3M's solvent. This was painted into the joint to fill/stick/weld/seal the joint. Similar to the solvent cement used on plastic waste pipes except we dissolved plastic the same colour as the mouldings. Finally we also joined very large polypropylene mouldings together. These were heat welded via a conductive metal braid laid in the plastic rim, mouldings were clamped together and large current passed through the braid to heat the joint and melt the plastic together. The same mouldings sometimes came in for repair and in that case we used a filler rod of the same plastic and melted it into the repair using a hot gun with a fine nozzle. As with normal welding of steel, cleanliness is important. In all the above cases I would say the join was stronger than the surrounding moulding, but only because of increased local thickness. At the end of the day it is the same material so unless it has been mistreated - over heated, contaminated with the wrong type of solvent or stressed in a way that breaks the length of the polymer chains then it will be as strong as the "base" plastic part. What are you wanting to join? And how are you proposing to do it? Roger |
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| Author: | new to this [ Mon Jun 21, 2021 10:30 pm ] |
| Post subject: | Re: plastic welding |
Roger Thanks for feed back,im tring to modify a inner plastic front arch to fit the Dolomite,So far i tiried closing off gaps with fibre glass but have found it to rigid,so now thought about plastic welding to close of gaps Dave |
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| Author: | TrustNo1 [ Tue Jun 22, 2021 7:59 pm ] |
| Post subject: | Re: plastic welding |
Quote: On another product we "solvent welded" parts together using granules of raw plastic "melted" or "dissolved" in a 3M's solvent. This was painted into the joint to fill/stick/weld/seal the joint. Similar to the solvent cement used on plastic waste pipes except we dissolved plastic the same colour as the mouldings. Roger Best method for DIY would be a a plastic cement as said similar as used for pipe work. as with any type of welding the type of joint (Lapping/ butt/ folding) when done properly will dictate the strength. |
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| Author: | naskeet [ Tue Aug 23, 2022 8:53 pm ] |
| Post subject: | Re: plastic welding |
I have done plastic welding in the past using one or both of an electric soldering iron or a metal spatula / palette-knife heated on the gas stove; infilling with slivers of the appropriate type of plastic. This tecnique worked well for me when modifying a Vauxhall Cavalier fuse cum relay box for use in my 1973 VW Type 2 Transporter. 
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