Plastic Welding: How to Weld Plastic

The plastic welding technique is almost similar to spot welding, but only differs by the fact that in plastic welding, heat is supplied through convection of the pincher tips, in place of electrical conduction. The two plastic pieces are brought together and heated tips pinch them, which causes them to melt and join. During welding, a jet of hot air is produced which melts the parts to be joined along with the plastic filler rod. As the rod melts, it is forced into the joint and fused to the parts.

The first thing to be considered while welding plastic, is to have good plastic identification, so you can accordingly choose an appropriate plastic welding rod. A plastic welding rod or thermoplastic welding rod, is of a constant cross-section shape which is used to combine two pieces of plastic together. It is commonly used for plastic welding and may have a circular or triangular cross section. An important feature of the plastic welding rod is its porosity. A rod with high porosity will cause air bubbles in the rod, which decreases the quality of the welding. Hence, the rods used should have zero porosity or should be voidless.

How to Weld Plastic

Before starting, make sure the work area is clean and ventilated. While using the mini-weld plastic welder, be careful as it is very hot and can cause burns or can even start a fire. Set the welder to preheat and keep the welder in the stand. Clean the part that you want to weld, and this can be done by using water and soap. Place the pieces together and use alumni tape to hold them in position. If the pieces are painted, then it is required to sand away the paint from the area you are working on. Make a v-groove at the spot you are welding with the help of a grinder. Melt the rod by placing the welder tip on the surface of the plastic. Draw the welder towards yourself in order to see the welding rod fill the v-groove as you make the pass. Before the melted rod cools down, take the hot welding tip to the same point and thoroughly melt the rod and the base material together. Maintain the heat till you have a good blend between the rod and the base material. If required, wire mesh can also be heated into the repair area for additional support, but make sure that it should be covered with plastic. While welding thin plastic, be careful as it can melt a hole in the base material. Once done with the front side, repeat the same procedure for the back side also. Now after the part has cooled, you can grind the weld down. Initially, use a coarse sandpaper and then use a finer one. Once you are done, don't forget to turn off the welder, place it in its holder and allow it cool down.

Plastic welding is a technique used for manufacturing products like chemical tanks, water tanks, heat exchangers and plumbing fittings. It not only saves money, but if done safely, it can be fun too.