Joining Two Piece of Glass Filled (30%) Nylon

[Wchen]

Hello everyone. I have small personal project that I would like some help on. I need to join two piece of glass filled nylon with not a lot of surface area to work with. The joint needs to withstand 200+ degrees Fahrenheit as well as some impulse energy. My primary question is should I use adhesive or plastic welding to join the two pieces. I have some scarp that I can use for the plastic welding by using a small soldering iron-like hand tool but I would like to know if Devcon Plastic Welder adhesive might give a similar result. Thanks for reading.

 

[patprimmer]

Nylon is quite difficult to join.

It is even more difficult when it is glass filled.

Acrylocyanurates give a reasonable result with a good joint design like if it has dowels or stakes or dovetails and the glue simply holds it in place but mechanical design takes most of the load or if there is a large surface area more in shear than tension.

Ultrasonic welding works well if you have the time and equipment to experiment a bit and get it right. I very much doubt that is your case from what you say.

Concentrated formic acid works well as a solvent glue on unfilled. I can work on glass filled but not so well. It is a moderately dangerous chemical to handle, being the sting in an ants sting.

Dissolving extra unfilled nylon of the same type in the formic before using might help with a glass filled grade as it will act as a filler to prevent the joint becoming glass rich and not fusing.

They will all work best if you can dry the naturally absorbed water out of the nylon first. How to do that best depends on a number of variables.

Regards
Pat
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[Wchen]

Thank you very much for the prompt response. I really appreciate it. Instead doing solvent welding with formic acid, what do you think about melting the contact area with heat while feeding scrap of the same material into the joint?

 

[patprimmer]

You will end up with a dirty contaminated charred and burned mess that will be glass rich as the resin melts away and burns.

You cannot do nylon by a soldering iron. It degrades quite quickly at its melting point when in contact with air and even more so if it has absorbed water, which it does fairly quickly on exposure to normal air.

Regards
Pat
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[dgallup]

Ultrasonic welding can work well with filled nylons. But you need to design the joint and the tooling specifically for the weld. Spin welding can work well to if the parts can rotate as they come together.

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[Demon3]

Vibrational welding is the same as ultrasonic welding essentially (same idea just different frequencies) and will work too. Except ultrasonic welding requires you to design the joint to concentrate the energy correctly but vibrational welding does not. I am not an expert on this but I have used both on a small scale to join glass-filled nylon.

Chris DeArmitt - PhD FRSC CChem
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