Joining mechanisms Welding, vibration

The part assembly design addresses the ability to join/assemble the component parts. Where the components are assembled with adhesives, it is important to know the compatibility and strength of adhesion to dissimilar substrates, in addition to the chemical compatibility of the plastic with the specific adhesive and its constituents. If melt bonding methods, like ultrasonic, vibration, or spin-welding processes, are employed, thermal compatibility aspects have to be taken into account. The broad possibilities of mechanical assembly methods include snap fits, press fits, bolts, and threads. The material properties needed for each of these design calculations are listed in Table 11.9. 

In ultrasonic welding, high-frequency vibrations in the form of mechanical motion are used to melt the joining surfaces of glass-reinforced parts and fuse them together with a strong molecular bond. Weld strengths are about 70% of the ulti-... 

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