Plastic welding

[oldsohc]

Just curious what the success rate for plastic welding is? I'm talking typical plastics you find on automobiles, plastic interior panels etc... I've tried my luck on some cracked polypropylene interior pieces in the past and the weld is always brittle and hairline cracks with ease. Perhaps it's because the iron was too hot? Or the plastic was too old? What are the variables in play here?

I know PP is a low surface energy plastic, so it's hard for glue to bond to it. But how about the ability of PP to fuse with itself or to fresh PP filler rod in regards to plastic welding?

I'm curious know other's people experiences with plastic welding.

 

[JeffKeryk]

My body man tells me it works fine for appropriate applications.
But an inappropriate fix is temporary at best.
A friend's TSX had a cracked grille; I thought he hit something. He said no...
Took it to Alex; he knew immeadiately it was a plastic weld which was a bad fix.

 

[AutoMechanic]

Never done it except with JB Weld lol

 

[tnt_motorsports]

I plastic welded the hood on my JD LT150. I bought the welder at HF and the filler rod of Amazon. The key is to use the correct filler rod.

1300 Watt Plastic Welding Kit with Air Motor and Temperature Adjustment

Amazing deals on this 1300W Plastic Welder Air Motor & Adj Temp at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Just my $0.02

 

[ABN_CBT_ENGR]

What are the variables in play here?

Had to NDT and DT a few, let me give you some guidelines as to what to look for based on failure analysis. Assuming a plastic that can be welded...

1- obviously get the right filler and heat source

Assuming weathered material- you must do an aging check to determine hw much ( if any) loss of working ability in the plastic. ( that's a wide range) because there is a "point of no return" where the repair simply cannot be done.

Grind the surface a bit- no matter how much you may think you clean, you don't - because things can imbed as well as bond with a plastic. Don use anything that sheds.

Prep like a regular tapered butt joint

Make sure there is mechanical tension/placement present so the weld is not stressed during the welding and curing cycle.

Know the temp and preheat until soft for the greater mass then apply the filler to temp so they bond.

Control cool if possible ( like a casting)

A lot of what's important depends on the specific material/aging and the joint geometry.

 

[atikovi]

Just curious what the success rate for plastic welding is? I'm talking typical plastics you find on automobiles, plastic interior panels etc... I've tried my luck on some cracked polypropylene interior pieces in the past and the weld is always brittle and hairline cracks with ease.

If you're working on old dried out pieces, nothing is going to work or last for long. The weld might hold up but the piece will crack somewhere else. Also, there are many high strength plastic adhesives nowadays that work as well as welding. Some manufacturers use it in place of welding metal body panels.

 

[Trav]

Just curious what the success rate for plastic welding is? I'm talking typical plastics you find on automobiles, plastic interior panels etc... I've tried my luck on some cracked polypropylene interior pieces in the past and the weld is always brittle and hairline cracks with ease. Perhaps it's because the iron was too hot? Or the plastic was too old? What are the variables in play here?

I know PP is a low surface energy plastic, so it's hard for glue to bond to it. But how about the ability of PP to fuse with itself or to fresh PP filler rod in regards to plastic welding?

I'm curious know other's people experiences with plastic welding.

I have found that regardless of the method used reinforcement with hot staples really helps strengthens the part if its thick enough to be used on eg, bumper, fan shroud, etc. I use this little thing, it does a good job.

Amazon.com

 

[mattwithcats]

Acetone...

Acetone dissolves the polyner strings of the plastic, then when it evaporates, they reform.

I fixed my LEGO’s this way...

Wipe the edges with a soaked q-tip, then push together until dry....

Does not work on all plastics, however...