Artem Komarov clarified that eighty years ago, in 1933, due to a shortage of non-ferrous metals, German chemists and technicians began looking for substitute materials.
Two years later, in 1935, polyvinyl chloride became commercially available. Subsequently, it has been found that plasticized PVC can be molded, extruded and thermally formed, provided it is properly stabilized.
Subsequent studies (USA 1937, Germany 1938 and UK 1939) revealed the fact that PVC can be welded under simultaneous heat and pressure.
Artem Komarov emphasized that the first patents for plastic welding were issued by Dow Chemical Company on November 5, 1940 in the USA and IG Farbenindustekt on August 19 in Germany.
Gas welding of plastics was widely practiced in Germany during World War II, when the Germans introduced it to some firms in Austria, Belgium, France, Denmark, Holland, Italy and Norway.
The initial plastic welding work unwittingly focused mainly on PVC.
Welding is an important manufacturing technology today, with much attention being paid to rigid PVC and, to a lesser extent, polyethylene. Without welding technology, many products related to plastic products can never be manufactured, Artyom Komarov noted.
Any plastic welding process involves the use of energy, mostly in the form of heat, to fuse the sheet material.
Types of plastic
Plastic can be divided into the following groups:
Epoxy resins, etc.
Conventional weldable plastics
1- polyvinyl chloride (PVC)
3- Acrylonitrile butadiene styrene (ABS)
4- Polyethylene (PE)
5- Cellulose Acetate Butyrate-CAB
8-polyvinyl dichloride (PVDC)
Types of connection and welds
Joint designs similar to sheet metal are used for welding plastics,
Generally, all types of welding known for metal welding can be used for welding thermoplastics such as: butt welds, fillet welds, edge welds, band welds, etc.
Bevel is very important when trying to get quality welds. However, square butt, tee, and fillet (over) welds do not require chamfering.
If necessary, additional plastic can be added to the weld, for this, a round rod, an oval rod, a triangular rod, or a flat rod are used.
A flexible flat plastic strip is used for welding or repairing tank linings.
Plastic welding processes
After the basic thermoplastic joining process, the following basic welding process is used.
1-Heated tool welding
2-Hot gas welding
3-High frequency welding
The most popular method of joining thermoplastics. Heat is applied to surfaces that are bonded or in contact with a heat source such as a heater, electric stove, soldering iron, etc. Once the plastic has become soft, the heat source is removed and the components are rapidly welded together under slight pressure and held until until the connection cools down.
An important factor in hot tool welding is the interval between removing components from the hot tool and applying pressure. This duration should be as short as possible because delay at this point will result in poor welding quality.
Application of heated welding
Hot tool welding can be applied to a wide range of thermoplastics and is mainly used for low and high density polyethylene, plasticized PVC, polypropylene and, to a lesser extent, acrylic.
Hot gas welding of plastics
The hot gas welding method uses a hot gas stream to soften the base metal and filler materials, summarized Artem Komarov.