The weldable relay of thermoplastics can not fail to mention the requirements of ultrasonic welding for various plastics. The main factors include plastic structure, melting temperature, flexibility (hardness) and so on.
1. Plastic structure
The amorphous plastic molecules are arranged in disorder, showing a marked softening, melting and flowing temperature (Tg glass transition temperature). This type of resin can normally transmit supersonic vibration effectively and achieve good welding in a wide range of pressure / amplitude.
Semicrystalline plastic molecules are arranged orderly, with obvious melting point (Tm melting temperature) and refreezing point. Solid crystalline plastics are elastic and absorb part of the high frequency mechanical vibrations. Therefore, this kind of plastic is not easy to transmit ultrasonic vibration energy to the compression surface, which requires higher amplitude. A high energy (high melting heat) can be needed to break the semi crystalline structure and make the material from crystallizing to a viscous flow state, which determines the apparent melting point of this kind of material. Once the melting material leaves the heat source, the temperature decrease will result in the rapid solidification of the material. So the particularity of this kind of material must be considered (such as high amplitude, good design of joint point, effective contact with supersonic clamps, and excellent working equipment) to achieve the success of ultrasonic welding.
2. Types of plastics
The process of combining monomers is called polymerization. Plastic can be basically divided into two main categories: thermoplastic and thermosetting. The thermoplastic material can also be softened and molded again after heating and molding, which is only the change of the State - this characteristic makes the adaptability of the thermoplastic material ultrasonic welding. Thermosetting materials are produced by non inverse chemical reactions, and reheating or pressurizing can not soften the formed thermosetting products, so thermosetting materials have traditionally been considered to be unsuitable for the use of ultrasound.
3. Melting temperature
The higher the melting point of plastic, the more ultrasonic energy it needs to weld.
4. Hardness (elastic coefficient)
The hardness of materials affects the transmission of supersonic vibration effectively. In general, the harder material is, the stronger its conductivity.
Contact Person: Mrs. Admin/Abby/May/Tina//Aimee