Effect of plastic parts on ultrasonic welding

- Aug 24, 2018 -

1. Ultrasonic waves propagate in plastic parts. Plastic parts absorb or attenuate ultrasonic energy more or less, which has certain influence on ultrasonic processing. Plastics generally have amorphous materials, and hard rubber and soft rubber according to hardness. The distinction between the modulus and the modulus is, in general, the high-hardness, low-melting plastic ultrasonic processing performance is superior to the low-hardness, high-melting plastic. Therefore, this involves the near-far problem of ultrasonic machining distance.


2. The influence of the processing conditions of plastic parts on ultrasonic welding, the different processing forms of plastic parts through injection molding, extrusion or blow molding, and different processing conditions will form factors that have certain influence on ultrasonic welding.

  A. Humidity Defect: Humidity defects are generally formed during the process of making streaks or loose plastic parts. Humidity defects attenuate energy during welding, so that the sealing position seeps and lengthens the welding time. Therefore, the plastic parts with high humidity should be made before welding. Drying treatment. Such as polyoxymethylene.

  B. Influence of the injection molding process: The adjustment of the parameters of the injection molding process will lead to the following defects: a dimensional change (shrinkage, bending deformation) 2 weight change, three surface damage, four uniformity

  C. Storage period: After the plastic parts are injection-molded, they are generally placed for at least 24 hours, and then welded to eliminate the stress and deformation of the plastic parts. Plastic parts that are molded from amorphous plastics may not meet this requirement.

  D. Recycled plastics: The strength of recycled plastics is relatively poor, and the adaptability to ultrasonic welding is also poor. Therefore, if recycled plastics are used, various design dimensions should be considered as appropriate.

  E. Release agent and impurities: Release agents and impurities have a certain influence on ultrasonic welding. Although ultrasonic waves can shake off solvents, impurities, etc. on the machined surface, they should be removed as much as possible for sealing or high strength. In some cases, it is necessary to clean the plastic parts first.