Welding methods for plastics

Welding methods for plastics

Welding methods for plastics – Overview of welding methods for plastic.  Plastic welding – Welding of plastics – Welding af thermoplastics.

Welding of the plastic comprises a heating to melt the surfaces to be welded, and a compression. Heating is achieved through direct contact, heat radiation, frictional heat or electricity.

It is assumed in few simple steps before, the plastic parts are welded together, and optionally filler, are of the same type of plastics;. In general, cleaning, scraping of old surfaces, etc.. important, but is not mentioned further below.

Welding methods for plastics


Electrofusion –  Welding with Electrofusion Control Units

Used for pipes where fittings installed, after which heating is supplied fitting through an external source.

Fittings that can be formed as T-pieces, decreases joints etc.. consists in principle of a sleeve with 2 Contact, which shrinks upon heating. Inside the fittings are mounted a spiral of a resistance wire that generates heating , when power from electro-sleeve welding machine.

 


Extrusion welding

The plastic pieces to be welded, fixed relative to one another.

The weld surface is melted with hot air. Welding wire or granules driven through a heated screw, and into the weld through a teflonsko, which forms the weld groove at the same time it presses the molten plastic into the heated groove.

Extruder welding is used to PP, PE , PVDF, COULD, Nylon , PVC , PVC-C og PFA

 


High Frequency Welding , Radio Frequency (RF) Welding, HF welding

The area on the welding plastic workpieces with dielectric properties are pressed together and exposed to an electromagnetic field at high frequency. 13 to 100 MHz.

The heating power generated by the dielectric loss in the base material.

The items are held together until they are cooled.

Welding method can be used for Thermoplastic Polyurethane, Nylon, Celuoseacetat, PET, Some ABS blends, soft PVC soft or hard PVC, Soft PVC for polyurethane,

There are on the market individual films of PE and PP which can be welded.

Of materials that generally can not be welded , include PTFE, Polycarbonate,, acetal, Polystyrene, as well as to hard PVC produce poor results.

welding plastic butt welding extrudersvejsning sleeve welding hot air welding


 Induction welding

Ferromagnetic electric circuit incorporated in the welding area of the plastic goods.

The materials are pressed together and exposed to an electromagnetic field.

The heating power generated by the electrical losses in the electromagnetic field.

The items are held together until they are cooled.


Infrared welding – IR welding.

The joint area of the plastic goods are kept at a distance from a hot plate, to the surfaces of melt. The hot plate is removed and the melted surfaces are pressed together, and maintained for the items has cooled.

Heating – input through infrared radiation. When the heating is contactless is the maximum temperature is not limited by an anti-slip coating.

 


Wedge Welding  – Over lap welding with hot wedge.

Typically used for welding of geomembranes , tarpaulins, PE / PP and PVC foil.

Heating wedge heats surfaces between membranes , which are then compressed.

 


Laser welding 

Overlap weld: When 2 foils or thin items assembled, the laser light is transmitted unhindered through one material, so that the energy absorbed at the interface between the two sheets. Thus creating a very local melting zone between the two layers of plastic. Topics cools down under pressure.

Laser welding allows precise heat and high speeds on long runs.

The colors of the subjects is very important to how suitable a topic for this method where transparent to black the easiest to laser welding and white to white is the hardest.


Microwave welding

The area on the welding plastic workpieces with dielectric properties are pressed together and exposed to a microwave field in the area 2-10 GHz.

The heating power generated by the phase shift and the effect of polarization renounced energy in the base material. The items are held together until they are cooled.

welding plastic butt welding extrudersvejsning sleeve welding hot air welding


Socket welding 

The ends of the plastic blanks are heated respectively by inserting one end into a socket, and the other being outside a corresponding mandrel. Socket-forming mandrels are removed and the heated objects stuck together.

Sleeve-mandrels are typically made of aluminum, coated with Teflon, and stretched on a hot plate. Coated socket punches can be used up to 270 ° C. Muffedornsvejsning used for pipes of plastic types PP – PVDF GO ON , to which there are fittings.

 


Rotation friction welding  –  Spin Welding

The welding area should be symmetrical around , pressed against each other one topic during rotation, the other issue fixed.

The thus heat generated in the contact zone, welds the pieces together. Subjects are held together under pressure during the cooling.

The welding time can be controlled by, torsion resistance or distance on the finished item. It is possible to weld the connecting pieces and the like. angle.

The method is suitable for oxidation patch. Plastic der er rotationssvejst, must typically be reworked with a cutting tool. Spin welding is used for all types of thermoplastics. Spin welding is used for all types of thermoplastics.

 


Butt Welding – Mirror Welding – Hot Plate Welding

The joint area of the plastic pieces is held against a hot plate, to the surfaces of melt. The hot plate is removed and the melted surfaces are pressed together, and maintained for the items has cooled.

 

Injection molded items can often readily welded, pipes must be planed flat and cleaned , machined parts to be cleaned.

Method with standard temperature: The hot plate consists of an aluminum plate, coated with an anti-slip coating (tefloncoating), with built-in electric heaters, and controlled by a thermostatic or electronic control. This method, wherein the molten plastic achieves the same temperature as the hot plate, used for the thermoplastic welding with temperatures up to 270 ° C. This hot plate is also called a heating element.

Method of high temperature: The hot plate consists of a metal plate, without coating, with built-in electric heaters, and controlled by a thermostatic or electronic control. This method is used for thermoplastic welding temperatures above 270 ° C. The hot plate has a higher temperature than the melt onto the plastic. This method develops depending on the type of plastic a heavy smoke.

 



Ultrasonic welding 

The welding area on the plastic threads are pressed together. One topic is stuck in a fixture, whereas the other is affected by an ultrasonic welding horn. The horn to vibrate about. 20.000 to 50.000 times per second. The friction heat melts the plastic along the contact surface. The items are held together until they are cooled.

Ultrasonic welding is a very fast welding method , that’s used for spot welding, riveting of rivets and inserting metal objects and thread pieces in plast.Ultralyd also used for cutting textiles.

There are different welding equipment from handheld devices to fully automatic welding robots.

This method is best for plastics with a low modulus of elasticity. Small variations (eg. additives ) can significantly affect the strength of the weld. Ultrasound can be used for welding of Polystyrene – ABS – SAN – PC – PMMA – Polyester – PA 15% to 50% Glass fibers – PP + 15% Glass fibers – POM – amorphous PET.

 


Hot gas welding with welding wire

Typically used for plastic over 2 mm. thickness.

Wire welding: The plastic pieces to be welded, fixed relative to one another.

The weld, and a bit of the filler wire is heated with hot air, while the welding wire is pressed into the heated groove.

 


Hot gas welding with overlap 

Typically used for plastic films, tarpaulins and membranes up to 2 mm. thickness.

Overlap weld: The foil is placed with an overlap, typically between 10-50 mm. on top of a firm base. Between the layers melted the surface with a flat air nozzle, after which the two layers are pressed together with a pressure roller.

 


 Linear vibration friction welding – High Frequency Welding – Low Frequency Welding

High Frequency Welding: The materials are pressed against each other and vibrated with a frequency of 190 to 240Hz and a motion 0,07 to 2 mm.

Low Frequency Welding: The materials are pressed against each other and vibrated with a frequency of about. 100Hz and a motion 2 to 4 mm.

It thus accumulated heat seal plastic together. Subjects are held together under pressure during the cooling.

Welding method can be used for PUR – PA – PMMA – ABS – PP – PVC – PC – POM – PS – SAN – THAT

 

Welding methods for plastics