WELDING AT HIGH FREQUENCY

Welding at High Frequency Dielectric heating is accomplished with electrodes that are connected to a generator of voltage at high frequency. This method is very efficient but is restricted to polymers that exhibit a high electrical loss factor like PVC and other polar polymers. 

Bonding The use of solvents (mostly with a cement made of a viscous solution of the same polymer) is common for easily soluble amorphous polymers like acrylics, polystyrene, cellulose, and PVC. However, this method does not apply to most crystalline polymers. The proper choice of solvent (or mixture of solvents) also takes into account the desired rate of diffusion. In this matter, the concept of solubility parameters may be exploited when there is a similarity between polymer and solvent. Various glues may also be used (contact glue, epoxy) in order to bind plastics to each other, including crystalline polymers or thermosets. 

Another combination method is mechanical. It consists of using screws and pins, or ball and socket joints, wherein the elasticity and contractability are utilized for successful contact. Milling of most polymers resembles, in principle, that of soft metals, but in the case of rigid polymers care must be taken against cracking and intrusion of mechanical stresses. In design, sharp comers should definitely be avoided. 

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