Hot plate welding

Ethylene—tetrafluoroethylene copolymers respond weU to melt bonding to untreated aluminum, steel, and copper with peel strengths above 3.5 kN/m (20 Ibf/in.). Eor melt bonding to itself, hot-plate welding is used. The material is heated to 271—276°C, and the parts are pressed together during cooling. 

Welding ultrasound, friction, vibration and induction techniques give good results. Hot plate welding is not recommended. 

Heat Sealing - A method of joining plastic films by the simultaneous application of heat and pressure to the areas in contact. Heat can be applied using hot plate welding, dielectric heating, or ladiofrequency welding. 

This result governs melting, both in an extruder and in hot-plate welding. It only applies while is much less than the sheet thickness. It shows that conduction alone is too slow to melt thick layers of plastic it would take 100 s to melt a 3 mm surface layer. 

Polymers of different colors can be expected to weld differently by infrared welding. Not only are the issues of pigment-polymer interactions present such as the differences in weldability caused by white (titanium dioxide), hlack (carbon black) or other pigments, but heating times and depth of heating are likely to he affected by part color. This kind of phenomenon can already occur in conventional hot plate welding when, in some cases, red and black parts weld differently. It can be expected to become even more of an issue with infrared welding. These effects can he easily handled, but workers must be aware of their presence and how to control them. 

Polystyrene modified polyphenylene oxide (PPO) or Noryl can be hot plate welded at 260 to 288°C and 20 to 30 s contact time. Unmodified PPO can be welded at hot plate temperatures of 343°C. Excellent spin welded bonds are possible with modified polyphenylene oxide (PPO), because the low thermal conductivity of the resin prevents heat dissipation from the bonding surfaces. Typical spin welding conditions are rotational speed of 40 to 50 ft/min and a pressure of 300 to 400 psi. Spin time should be sufficient to ensure molten surfaces. 

The joining of two melt fronts that meet and solidify in a mold cavity. A bond formed during the assembly operation where the joint line is melted before assembly. See Hot-plate welding, Induction welding, and Ultrasonic sealing. ... 

Infrared welding has a number of advantages over hot-plate welding weld times are reduced, the joints are free from contamination (since it is a non-contact process) and low-modulus materials can be welded (since there is little or no shearing of the parts during heating). 

In hot-plate welding, the parts to be welded are held in fixtures, which press them against either side of a heated platen. Once the parts are sufficiently molten, the platen is removed. The components are then pressed together and held until they cool. Hot-plate welding is a... 

The most important application of hot-plate welding is in the joining of thermoplastic water, gas and effluent pipes, where it is often referred to as butt-fusion welding. It is also used by the automotive industry in the manufacmre of fluid reservoirs and in the welding of PVC door and window frames. 

Hot-plate welding (hot-tool welding) n. Two plastic surfaces to be joined are first held lightly against a heated metal surface, which may be coated with polytetrafluor-oethylene to prevent sticking, until the surface layers have melted. The surfaces are then quickly joined and held under fight pressure until the joint has cooled. 

Thermoband welding n. Trade name for a variant of hot-plate welding in which a metallic tape acting as a resistance element is adhered to the material to be welded. Low voltage is applied to heat the tape, and the adjacent plastic, to the plastic s melting range. Pressure may be applied to the joint while it cools. 

Figure H.2 In direct hot plate welding, two fixtures press components into a hot, movable plate, causing the plastic to melt at the interface. Subsequent removal of the plate, application of pressure on the joint, and cooling time allows the welded joint to form and gain strength.

Joining of plastic pipes is shown to be done more effectively, economically and in a much shorter time on-site by linear vibration welding , rather than the conventional hot plate welding or electrofusion welding techniques. 

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