Plastic welding methods

The experimental titanium alloy T110 produced by EBCH melting, subjected to plastic deformation and heat treatment, has characteristics of strength at a level of commercial alloy VT22, and is superior to this alloy in ductility and fatigue strength. The alloy is well-weldable with any fusion welding method. 

Welding methods are listed in Table 7.1. Ultrasonic welding is one of the most efficient methods of joining plastic parts, and different materials can be welded so long as they have a common monomer. While particularly useful for hard rigid materials, it may generate particles. 

The spin welding method is applicable to circular surfaces which must be bonded. The two pieces to be joined are slightly pressed together while one of the pieces is rapidly rotated. The friction thus generated heats the plastic... 

There are many different, cost-effective welding methods suitable for industrial mass production of plastics engineering components including ultrasonic, laser, spin, hot plate, linear and orbital vibration welding. Here we will deal with inexpensive manual methods for low quantities which can be carried out in small workshops or on site. 

Rigid polyvinyl chloride can be easily bonded with epoxies, urethanes, cyanoacrylates, and thermosetting acrylics. Flexible polyvinyl chloride parts present a problem because of plasticizer migration over time. Nitrile adhesives are recommended for bonding flexible polyvinyl chloride because of compatibility with the plasticizers used. Adhesives that are found to be compatible with one particular polyvinyl chloride plasticizer may not work with another formulation. Solvent cementing and thermal welding methods are also commonly used to bond both rigid and flexible polyvinyl chloride parts. 

It is possible to strip undercuts for parts molded of these processes in some cases and threads can be molded-in. However, side actions or split cavities, as would be required for details A and G, are more commonplace. Threaded inserts, like those at E and H, can also be molded-in. However, it may be more advantageous to emplace them after molding with adhesives since the molding cycle will be shorter and the risk of one misplaced insert ruining an entire moldment is ehminated. The other common methods of assembling compression, transfer, and thermoset injection-molded parts are self-tapping screws (holes can be tapped), adhesives, snap-fits, press-fits, and the usual screw and bolt techniques. None of the plastics welding techniques can be used with thermoset parts. 

Different rates of melting and different viscosities in the melt mean that individual plastics respond differently to the common welding methods. All of the following systems are in use ... 

Although other bonding methods were considered and evaluated, the results of which are beyond the scope of this paper, hot air bonding was the simplest to implement, most robust, and least expensive of the plastic welding alternatives considered in this study. Hot air bonding tests were conducted to fabricate felt-to-felt bonds (FFB) and TPU tape-to-TPU-coated felt bonds (TTB) in order to characterize the development of interfacial bond strength as a function of line speed (time) and temperature. 

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