Plastic welding

Hi everyone !
As I though it might be a good idea do find different way to assemble plastic together and I love welding, I made some trial on welding plastic.

I did it with an air heater, with a thin nozzle. I first apply it on the surface to be welded to start melting of the base material, then I added a thin part of an homogeneous plastic to create the joint.

I first try with 6 different ways of welding :
1- butt weld / no bevel / welded both side
2-  butt weld / V bevel / welded one side
3- butt weld / X bevel / welded both side
4- fillet weld / welded both side
5- angle weld / welded one side
6- socket weld / welded both side

On all of the sample I did a macro (this is why I used a rose plastic for filling) and a bend test up to rupture. On 1, 2, 4 & 5, it break in the weld or on the fusion line, mostly due to a bad fusion between my filler plastic and my plate. But 3 & 6 did well. It can open great possibilities for new design based on plates.

I fully documented it with picture and rupture facies description, what would be the best support to share it ?


Bonjour @lagrenouille !

Will you try other way to attach plastic ? A puzzle like way ? Screw ? …
I think it could be cool a topic where you share multiple way and tell advantages and disadvantages of each way.

To answer to your question, you can post it on the forum but you can only post 3 pictures, so you could do some montages but it’s not optimal.
I don’t really know where you can share it.
This site  could be used :

… I’m salvaging IR-Laserdiodes with 9Watts or 25Watts @976nm (they emits out of a fiber with 0,1mm, so usefull for laser-engraving) from broken fiberlasers (have more than hundred of the 9W and some ten of the 25W/30W-diodes) … or buying 25w @808nm diodes for around 65€ at ebay.

This 200W-diodes were a bit more expensive – 450€ the first four, then 300€ for the next four (two for a company projekt, six for my own).

So not this expensive 😉

You can find some infos about in this RepRap-threads:,13836,235148


100 watt diode lasers are quite expensive.  I think the last panasonic diode laser I handled was 40 watts and new price was more than my car.


Whereas a hot air plastic welder is less than a hundred USD



… use black (or dark dyed) sheets — then any high energy light source will melt it … e.g. focussed light of halogen bulbs (commonly used for soldering) or too focussed sun light.

I’m developing around high power laser diodes (200 Watts @965nm on a spot of 0,2mm!) for fusing/welding/3Dprinting with metal and other “tough” materials.

Here a video testing with roughly 100 Watts (half the CW power of a single diode) on a tile:

You can see the result of this test (a 4mm deep hole with 1mm diameter and “glassified” borders ) in the attached image.

My idea is to use several of this diodes (two for the actual project … have plans and 6 more of this diodes for a private buildup) from different sides …


Hi, I was just about to start a post on this topic.


I was thinking about welding plastic sheets together for a HDPE boat.


Any thoughts?

Hola la grenouille
vuala un link pour une machine pour souder plastics
ca pourra te donner des idées

Something for you to think about, maybe even try:- rough up the plastic a little in the area to be welded then run two small grooves parallel. As the weld then goes over top. The heat will penetrate further into both pieces and create a much stronger bond. If you were to angle the groove in a different  direction this may also add or detract strength.

I’ve done some tests with laser-welding plastics with laser-diodes and fiber-lasers – it works — the strength of the fused areas depends on injected energy and “treatment” or pulsing/pulse-shaping the laser beam.

But actually more focussed on fusing/welding metal wires …


have you tried LDPE ? (it fuses remarquably well together, have been testing it quite a lot recently) but then maybe would it create contamination if welded with HDPE  ?

Okay I understand 😉
I didn’t talk about glue :stuck_out_tongue: I know that glue it’s horrible (Bottles…)

But I think that assemble parts like puzzles could be nice 😀 And Plastic only
And this more discreet

You could also assemble parts like puzzle and then weld them to be sure that they stay stick.

I first planed to concentrate on a way of attachment that would also play a sealing part, and I don’t want to glue them for plastic contamination reason. But you idea is great, and plenty of attachment can be tested !