Electric fusion welding is the process of joining two plastic pipes together using a single-use coupler with integrated wire heating coils. The fused control unit supplies power to the coil, heats and melts the plastic. When cooled, a gas tight joint is formed.
When the electric heating coil is energized, the plastic material in contact therewith melts and forms an expanded pool of molten plastic that is in contact with the surface of the pipe. Continued heating causes the pipe surface to melt and then mix with the molten plastic of the fitting. This mixing is critical to producing good welds. Also, proper delivery of energy to the heating coil is critical to producing molten plastic and making the process happen.
At the end of the heating cycle, the fittings and pipes are cooled and the molten material is cured to form a strong and strong joint. During this cooling phase, the joint must remain completely stationary as movement can break the interface and cause a leak path.
In order to ensure a high quality joint, the following conditions must be met:
The heating coil needs to be as close as possible to the pipe/fitting interface.
The heat distribution is uniform over the length of the "hot zone".
Precise control of melt pressure and temperature.
Protect the heating coil from damage before soldering and during soldering.