What Effect Will Plastic Parts Treatment Have On Ultrasonic Welding?

Different processing forms such as extrusion, blow molding or injection molding and different processing conditions will have a certain impact on ultrasonic welding.

A. Humidity defect

Humidity defects are generally formed in the process of making striped or loose plastic parts. Humidity defects attenuate useful energy during welding, which makes the sealing position seep and lengthens the welding time. Therefore, plastic parts with high humidity shall be dried before welding. Such as polyoxymethylene.

B. Effect of injection molding process

The adjustment of injection molding process parameters will lead to the following defects:

① Dimensional change (shrinkage, bending deformation)

② Weight change

③ Surface damage

④ Poor uniformity

C. Shelf life

After the plastic parts are processed by injection molding, they are generally placed for 24 hours before welding, so as to eliminate the stress, deformation and other factors of the plastic parts. Plastic parts made of amorphous plastic through injection molding may not meet this requirement.

D. Recycled plastics

Recycled plastics have poor strength and poor adaptability to ultrasonic welding. Therefore, if recycled plastics are used, various design sizes should be considered as appropriate.

E. Release agent and impurities

Mold release agent and impurities have certain influence on ultrasonic welding. Although the solvents and impurities on the machined surface can be shaken off during ultrasonic processing, they should be removed as much as possible when sealing is required or when high strength is required. In some cases, it is necessary to clean the plastic parts first.