Each welding method has its own characteristic properties and it is therefore important to make the right choice of welding method. There is a high level of flexibility in plastics today, and a wide variety of structures can now be made for all kinds of applications. 

The following is an overview of the leading welding techniques that are in use.

The following information is intended to provide theoretical explanations. No unconditional guarantee is therefore offered if it is used as described.

Do you want to know more about welding? NKI can help you in this regard.

Extrusion welding

Where used– in all kinds of PE/PP structures with plate material or for processing thick-walled material.

Principle - The extruder is fed with PE / PP welding wire (2 mm to 5 mm) from a roll. The welding wire heats up immediately after uptake, and the worm screw then works it into a mouldable mass. This mass leaves the extruder via the discharge opening and the welder ensures that the desired welding joints are made with a specific pressure, speed and conduction

Electrical socket welding

Where used- where it is preferred to weld a pipe and injection-moulded electrically welded fittings to each other, this can be easily done using a welding transformer.

Principle - The injection-moulded fittings are fitted with a positive and a negative pole in the form of welding pins.
The plugs of the welding transformer are attached to the welding pins and when the button is pressed, the welding process is started and ended via a computer-controlled system. Since the sockets of the electrical welding fittings are equipped with a copper coil that heats up greatly due to electrical conduction, the tube and the fitting take on a mouldable form, and through heat expansion of the tube and fitting, and after the welding procedure, they automatically cool down under pressure and the electrical welding connection is thereby created.

heat reflector welding

Where used - if you want to weld a PE / PP tube and/or (key) fittings to each other. 

Principle - The material becomes mouldable due to the heat transfer (under pressure) from the heat reflector on the tube and/or fittings to be welded.
The heat-reflector connection will be completed if cooling is done at the correct temperature and pressure for the exact time.

wire welding

Where used - this versatile technology can be used everywhere for the following applications due to its easy-to-use design. In many kinds of structures, equipment manufacturing and pipeline construction.

Principle - The welding gun is a manually operated device equipped with a welding nozzle through which the PP/PE/PVC welding wire passes. A heating element brings the welding wire (2mm/3mm) to near-moulding consistency. The welder shall decide the type of welding wire to be used, the speed of welding, the trigger pressure on the welding gun, and the method of making the various welding joints.

socket welding

Where used -for PP tubes and fittings. The major advantage in this welding method is that no welding groove is formed on the inside of the tube or fitting. There is therefore no narrowing, deposit of contaminants or pressure loss in the pipeline system.

Principle - The outer side of the tube and the inner side of the fitting simultaneously become mouldable. The tube and the fitting are directly pushed into each other so that they can cool.