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What materials can be ultrasonically welded?

Ultrasonic plastic welding machines have been widely used in industrial production. Generally, all thermoplastics except PTFE(a synthetic fluoropolymer of tetrafluoroethylene) can be welded ultrasonically. Especially ABS and PS can be welded to perfect and traceless products through ultrasonic. However, due to differences in acoustic resistance, melting point, etc., different materials generally cannot be welded together by ultrasonic.

How to distinguish thermoplastics and thermosetting plastics

Plastics can be divided into thermoplastics and thermosetting plastics based on processing properties. Thermoplastics soften as temperatures rise, harden as temperatures fall, and so on. Thermoset plastics are plastics that solidify at a certain temperature. After solidification, chemical reactions and repeated softening no longer occur. But when the temperature is too high, thermoset plastics will break down.
From a chemical perspective, thermoplastics are composed of linear molecular chains. When the glass transition temperature is reached, the molecular chains begin to move and combine with each other. After the temperature is lowered, the recombined molecular chains gradually stabilize, which is also the principle why ultrasonic waves can stably weld thermoplastics. The molecular chains of thermosetting plastics form a grid, and the molecular chains will be destroyed and decomposed when heated.

What materials can be ultrasonically welded
plastic materials

Can Plastics Transmit Ultrasonic Energy Well?

Through the principle of ultrasonic welding, we know that ultrasonic welding is to pressurize the high-frequency vibration energy to the surface of the plastic product, and the ultrasonic energy is transmitted between the plastic upper shell and the lower shell, because the acoustic resistance is large here, and heat occurs here. , thereby melting the plastic. Therefore, whether the plastic can be welded by the ultrasonic plastic welding process, it is necessary to understand that this plastic can effectively transmit ultrasonic energy. For plastics that cannot transmit ultrasonic energy well, heat will occur on the surface of the product, that is, where it is in contact with the ultrasonic mold. Therefore, the surface of plastic products that cannot be welded will be very hot or even rotten after welding.

Choose Ultrasonic Welder for Your Project

Many plastics of different materials can be ultrasonically welded, but some plastics of the same material cannot be ultrasonically welded. For materials that are more difficult to weld, it is necessary to select ultrasonic welding equipment with higher power and stronger amplitude according to the characteristics of the material and the specific structure of the product, and some products need to choose a higher frequency ultrasonic welding machine to achieve welding. For details, please feel free to consult our professional technical personnel for judgment.

plastic product

Plastic Materials Much Suitable for Ultrasonic Welding

ABS

ABS is a styrene copolymer, this material is the best material for ultrasonic welding, but this material is more expensive. ABS has the advantages of light weight, high impact resistance, high heat resistance, flame retardancy, reinforcement, and transparency; it is a thermoplastic engineering plastic with a wide range of uses. Widely used in machinery, automobiles, electronic appliances, instrumentation, textiles and construction, and other industrial fields.

PS

PS is polystyrene, this material is also a relatively light material, with good transparency (light transmittance 88%-92%) and surface gloss, easy to dye, high hardness, good rigidity, and good water resistance. It is widely used in industrial fields such as electronic appliances, construction, and daily necessities, and is suitable for welding with ultrasonic welding machines.

PMMA

PMMA is an acrylic material with a low melting point, high light transmittance, low density, good processing performance, and good stability, and is more suitable for ultrasonic welding. Acrylic plastic is relatively brittle, and the pressure time of ultrasonic welding should not be too long, otherwise, it will cause cracks.

plastic material analyse for ultrasonic welding
Analysis of Plastic Materials that difficult welded in Ultrasonic Plastic Welding

1 Polypropylene, referred to as PP, is the only plastic material that can be placed in a microwave oven, with a melting point of 167°C. Moreover, the material is relatively light, has good insulation, and the low elastic coefficient is easier to slow down the ultrasonic vibration;
2 Nylon, referred to as PA, nylon is a synthetic thermoplastic linear polyamide with excellent strength, relatively good wear resistance, and moisture absorption;
Polyoxymethylene, referred to as POM, is easy to crystallize, with a crystallinity of 70%; high strength and stiffness;
3 Polyphenylene sulfide referred to as PPS, has high mechanical strength, high-temperature resistance, and good thermal stability.
4 Polyethylene, referred to as PE, this material is relatively soft, so it is not easy to weld, and the difficulty of welding is relatively reduced with high density.
5 Polyvinyl chloride, referred to as PVC, therefore, the material is soft and difficult to weld, so few people use this material, and the products of this material are generally welded with high-frequency waves.
6 Polycarbonate referred to as PC, high melting point and a long welding time.
7 Polypropylene referred to as PP, this material is difficult to weld due to its low elastic coefficient, which is easy to attenuate sonic vibration.

 

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