Thermoplastics induction welding

Thermoplastics Mechanical Fasteners Adhesives Spin and Vibration Welding Thermal Welding Ultrasonic Welding Induction Welding Remarks... 

Ultrasonic welding is a frictional process that has been well established for heat welding thermoplastic parts. Like induction welding, it also has been adapted for curing structural adhesives such as epoxy. 

Based on the principle of dielectric loss, induction welding is particularly suitable for high-loss thermoplastics such as PVC. However, by adapting certain measures, PVDF films from 10 to 50 pm can be welded. 

One of the fastest methods of bonding ABS and acetal thermoplastics is induction welding. This process usually takes 3 to 10 s, but can be done in as little as 1 s. During welding, a constant pressure of at least 100 Ih/in should be applied on the joint to minimize the development of bubbles this pressure should be maintained until the joint has sufficiently cooled. When used, metal inserts should be 0.02 to 0.04 in thick. Joints should be designed to enclose the metal insert completely. Inserts made of carbon steel require less power for heating althougdi other types of metal can be used. The insert should be located... 

Plastics that are readily bonded with induction methods include all grades of acrylonitrile butadiene styrene (ABS), nylon, polyester, polyethylene, polypropylene, and polystyrene, as well as those materials often considered more difficult to bond such as acetals, modified polyphenylene oxide, and polycarbonate. Reinforced thermoplastics with filler levels up to 65 pCTcent have been joined successfully. Many combinations of dissimilar materials can be bonded with induction welding processes. 

Moser L, Mitschang P and Schlarb A K (2008) Induction welding of thermoplastic polymer composites using robotic techniques, SAMPE J 44 43-49. 

In implant resistance welding, an electrically resistive element that is placed at the joint interface is heating by either direct or alternating current [2], The resistive implant may be as simple as a nichrome or stainless steel wire or mesh. More complex implants can be tapes of braided metallic wire with thermoplastic monofilaments or a composite of polymer matrix with electrically conductive particles or fibers. As shown in Fig. 26.26, during implant induction welding, the resistive implant is placed between the two parts. Electric current is then passed for a preset time through the resistance implant while the parts are under pressure. Then the current flow stops and the parts are kept under pressure while the weld cools, and the implant remains at the joint interface. 

Induction welding is less dependent than other welding methods on the properties of the materials being welded. It can be used to weld almost all thermoplastics, crystalline and amorphous. 

Butt Joint Strength of Thermoplastics from Induction Welding... 

R. Nichols, V. Kagan, Induction welding takes aim for reinforced thermoplastics in high performance and load bearing applications , Proc. of ANTEC (2004)... 

R. Nichols, Advances in the Emabond Induction Welding Process for High Performance Assembly of Demanding Thermoplastics , Assembly Technical Expo (2003)... 

A joint of the same thermoplastic to be welded or compatible with it, containing ferromagnetic particles, is located between the two surfaces to be welded. When passed through an induction coil, this joint melts and causes melting of the surfaces in contact. 

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