Butt welding is a welding technique used to connect parts which are nearly parallel and don't overlap. It can be used to run a processing machine continuously, as opposed to having to restart such machine with a new supply of metals. Butt-welding is an economical and reliable way of joining without using additional components.
Usually, a butt-welding joint is made by gradually heating up the two weld ends with a weld plate and then joining them under a specific pressure. This process is very suitable for prefabrication and producing special fittings. Afterward, the material is usually ground down to a smooth finish and either sent on its way to the processing machine, or sold as a completed product.
Heat fusion (sometimes called heat welding, butt welding or simply fusion) is a welding process used to join two different pieces of a thermoplastic. This process involves heating both pieces simultaneously and pressing them together. The two pieces then cool together and form a permanent bond. When done properly, the two pieces become indistinguishable from each other. Dissimilar plastics can result in improper bonding. This process is commonly used in plastic pressure pipe systems to join a pipe and fitting together, or to join a length of pipe directly to another length of pipe. Generally, polyolefins (such as polypropylene, polyethylene, and polybutylene) and PVC are used for these applications.