Learn About Welding Plastics

Plastic Welding – The basics
We recently took a trip to RIPCO who are a long established plastic fabrication company and asked Steve the owner to give a few tips on the basics. What we discovered is as always, there’s a lot more to this plastic welding and fabrication industry than initially meets the eye and we’re only going to be able to scratch the surface.

Preparation
RIPCO like to scrape the immediate faces of the plastic at the joint area, this apparently helps remove any unwanted surface contaminants and also gives a better key because the shiny surface has been removed.

Tacking things in place
Holding the plastics exactly where he wants them, Steve runs the welding torch down the whole joint without the weld rod in, this creates a joint strong enough to hold the materials in place and also helps prevent distortion when the real welding starts.

The actual welding bit
After cutting a length of welding rod off the roll at a few inches longer than the length of the weld he’s going to do. Steve starts the process by holding the nozzle tight into the joint and at forty five degrees to the corner; Steve then works his way down the joint feeding the welding wire in as he goes. Now this is the bit that he makes look very easy but you can just tell that the speed and feed that he’s moving down the joint has come about through many years of practice. To increase the strength even more by the way, extra lines of weld can be added either side to build up the weld joint.

Welding guns & machines
The welder in the video is apparently a Wegener brand and we’re told they are around £300 but there are probably equivalents out there equally as good, this type has a heating element inside and a fan which blows the hot air which is directed by the special nozzles to melt the plastic together. RIPCO have other types of welders called “extruder welder”, they are a bit more complex in the way that they actually completely melt the welding rod inside the gun and the molten plastic is extruded out of the nozzle, these are for the bigger jobs, its a good job because they cost an estimated £3000 each

Welding rod
One thing to remember is that the welding rod needs to be the same plastic, pretty obvious i suppose but for example if you’re welding polypropylene homopolymer or copolymer grade, you will need to be exact and get the right matching weld rod.

We noticed there are different shapes of welding rod, Steve suggest that 3mm diameter round rod is a pretty good bet for most jobs and the 4mm diameter is used on bigger projects.

Elf & Safety
Obviously these heat guns are incredibly hot so the whole weld area is going to be pretty warm for quite a while but the gun and nozzle themselves are going to be super hot so be careful going anywhere near the nozzle and take care where you put the machine down and it would probably be a great idea to wear protective gloves etc.