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How to choose plastic welding equipment
Jan 24, 2018

There are generally two ways to connect plastic: bonding and welding. Generally speaking, the bonding process production efficiency is low, not beautiful, and adhesives have a certain degree of toxicity, and the welding process relatively high production efficiency, beautiful welding, high welding strength, so the plastic welding process has been more and more widely used.

First, select the correct weldable material. In the actual production process, only the molecular structure of the same or similar to the thermoplastic plastic can be welded. In the welding surface is the chemical bond between the molecules, so the more similar maternal materials, the better the welding effect. At the same time, the content of filler in plastics has a great relationship with the weldability and welding quality of plastics, and they change the physical properties of the material. When the filler content is more than 30%, due to insufficient surface plastic ratio, the fusion between molecules is not enough, will reduce the welding tightness.

Secondly, according to the type of material and product shape, cost of the high and low to take appropriate welding methods. According to the different heating and softening method, plastic welding can be divided into several kinds, such as heat source, mechanical motion and softening of electromagnetic action.

First, through the addition of heat softening welding technology:

1, Hot plate welding

Hot plate welding is to use planar heating plate will need to weld the two plane melt softened quickly remove the heating plate, a welding method incorporating two planes and afterburner to cool is suitable for the weld of a non rotating workpiece or a large plastic workpiece, which is difficult to melt, this method has high welding strength and the shape design of welding parts is relatively easy, for example, the car water tank , automobile toolbox, car combination lamp, washing machine balance ring and other products.

2. Hot Air Welding

When the hot air airflow is blown directly to the seam zone, the filler wire and the seam zone are fused with the material of the base material, and the filler material melts with the welded plastic to form the weld seam. The advantage of this welding method is that the welding equipment is lightweight and easy to carry, but the welding skill of the operator is very high.

3, Hot rod and pulse welding

These two techniques are mainly used in the welding of small plastic film. And the two methods are similar, are two film tightly pressed together, the use of hot rods or Shan generated by instantaneous heat to complete the welding.

Second, through mechanical movement to soften the completion of the welding method:

Mechanical movement welding is a fully automatic welding process, the use of pressure under the two workpiece in the friction process of heat generated to melt the contact surface of the plastic, on the fixed until the condensation firmly, the need for special welding equipment. Once the correct welding parameters have been determined, the operator can stabilize the production. Its advantages are: fast, flexible, stable welding process and no flux or protection of gas, also do not produce harmful gas or slag, product welding quality assurance. According to the movement of the track can be divided into linear and rotational type: linear type can be used for straight line weld and planar weld, rotary type can be used for welding round welds.

1. Ultrasonic welding

Ultrasonic welding is generated by the signal generator high-frequency sine wave signal, by converting the transducer into high-frequency mechanical vibration energy, and then by the horn and the welding head to the amplified vibration coupled to the welded plastic parts, high pressure high frequency friction makes the plastic contact surface instantly produce high temperature melting, after the ultrasonic stopped, After a brief cooling of two plastic parts will be welded into one, welding process generally not more than a second, welding strong

Degree can be comparable to the body, widely used in electronic appliances, auto parts, packaging, plastic toys, stationery, daily necessities, handicrafts and other industries. When welding plastic products, do not add any adhesive, filler or flux, also do not consume a large number of heat sources, with easy to operate, welding speed, high welding strength, beautiful welding, the advantages of high production efficiency. In addition, the ultrasonic welding process can also achieve the plastic and metal parts riveting. Therefore, ultrasonic welding technology is more and more widely used.

2. Rotary Friction Welding

The mechanical energy can be converted into heat energy by the workpiece's relatively high speed rotational friction, which heats up the contact surface friction of the workpiece, and then is pressurized and welded together. Compared with the ultrasonic welding, the process is not limited by workpiece size and material, and the welding strength of other plastic welding process is higher, almost close to the plastic body strength. It is suitable for the welding of workpiece such as cartridge, plastic cup, float ball, toy ball and shower.

Welding method of softening surface by electromagnetic action:

1, high-frequency welding

High-frequency welding is the use of electromagnetic induction principle of high-frequency induction heating technology, penetrating plastic products to the internal plastic embedded in the sensor body or magnetic plastic to produce induction heating, so that the welded plastic in the rapid alternating heat and make the welding site quickly softened melting, and then fill the interface gap, and supplemented by a perfect mechanical device to achieve perfect welding. Apply to Stationery folder, inflatable items, waterproof clothing and blood bags and other products welding.

2, Infrared welding

This technology is similar to the electric heating plate welding, will need to weld the two parts fixed in close to the heating plate place but not with the electric plate contact. Under the action of heat radiation, the connection part is melted, then the heat source is removed, and the two parts are docked and pressed together to complete the welding. This method does not produce solder slag, non-polluting, welding strength, mainly for PVDF, PP and other high-precision piping system welding.

3. Laser Welding

The principle is a light path system consisting of a laser beam generated by a reflector, lens, or fiber. Focusing on the area to be welded, forming the thermal zone, the plastic in the hot zone is softened and melted, in the subsequent solidification process, the melted material forms a joint, the parts to be welded are connected, usually used for PMMA, PC, ABS, LDPE, HDPE, PVC, PA6, PA66, PS and other materials such as good transmittance welding, in the thermal action zone, such as carbon black and other absorbent to enhance the endothermic effect. Plastic laser welding has many advantages: fast welding speed, high precision, automation, precision CNC easy to implement. Therefore, the plastic laser welding technology in the automotive, medical equipment, packaging and other fields have been more widely used.

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