Plastic welding

Emp_Fab

Would anyone know what type of plastic is used in dishwashers ?  The plastic screw mounting posts that hold the fascia of my dishwasher onto the metal panel behind have snapped off (due to repeated dismantling for repairs !).  I've lost several of the posts so need to recreate them using some plastic round bar stock.  I can weld it to the back of the fascia with a soldering iron, as glue is a complete waste of time as I've learned over the years.  Plastic welding FTW !

Anyhoo...  you can only weld plastics of the same kind and I don't want to order a length of, say, HDPE if it turns out the fascia is made of, polypropylene for example.

I can't see any obvious marks to indicate the type of plastic it is and the burn test is open to misinterpretation of the results.

Any plastics peeps here ?

Nikko

No specs on the manufacturers website?

Mkjackary

Best to contact the manufacturer and ask them, may take a while, but should eventually get you the right answer

octatonic

I did this as part of my B.Sc.
The best way to work it out, unfortunately, is the burn test.
If you do it properly then the results should not be inconclusive.

Have a look here: http://www.boedeker.com/bpi-burn.pdf

Col_Decker

What something like an epoxy-resin? much stronger than glue.

Nomad

Quite likely to be ABS. Sand a bit of scrap and see if it smells like ABS.

octatonic

If it is ABS then you can melt and re-bond with acetone.

Emp_Fab

I just tried it with acetone... nothing doing.  Didn't melt it at all despite furious rubbing.  Must be something else.

Corvus

Re the above a biker's dodge is get some lego & acetone, dissolve the bits in it to make a paste. Soften up the bits to be joined, they do need to be quite soft there to 'weld' and acetone dries pdq so it's a chasing game. Then 'glue' the bits together with your lego glop, Often used to repair cracks and sometimes fix bust lugs so might work. Messy & smelly though.
But welding with an iron is smelly (and poisonous I think), I repaired a bit of bike helmet visor with it lots of times, it works but you have to really stir it around to get a decent bond going. Didn't worry too much about the filler plastic, just picked stuff that felt & looked the same.

octatonic

Emp_Fab said:

I just tried it with acetone... nothing doing.  Didn't melt it at all despite furious rubbing.  Must be something else.

Yes, it isn't ABS if acetone doesn't melt it.
Also assuming you used 100% acetone.
Some cheap nail polish removers are labelled acetone but seem to be adulterated with other stuff.

lasermonkey

Maybe worth trying MEK (methyl ethyl ketone) which is often sold in model shops as Plastic Weld or Plastic Magic, etc.

bazxkr

How about using another method like the plastic 'rivets' that they use on cars that act like a rawlplug when you drive home the rivet. Some of the car ones are cosmetically decent looking and should do the job. And if you want them out it's easy although you have to replace with new. They use these on exterior trim as well as interior so there are varying types from a strength point of view. Do away with the original method entirely. Just thinking outside the box for an easy hit.