UPVC windows are made from sections of profile, which are cut and joined together to for the shape of the window. These profiles are produced by forcing molten PVC through a precision die, the material is cooled almost immediately before being cut to length. The flatness, squareness, and straightness of the profile is maintained by the design characteristics of the profile and the tooling.
The windows are then fabricated from pieces of profile that have been cut to the correct size. These pieces of profiles are joined together using either heat-fusion welding or T-joint connectors. Steel or aluminium reinforcement sections are fixed inside the UPVC profiles to provide additional strength, where required.
Additives and Stabilisers
UPVC is based on the polyvinyl chloride polymer, however, in order to make the material suitable for use as a window, a number of different additives and stabilisers are used. These special heat and UV stabiliser additives are an essential part of any PVC formulations destined for the manufacture of PVC-U windows.
The choice of stabiliser will largely depend on the particular end-application, and there are good technical reasons why certain stabiliser types are used for specific applications. Stabilisers often comprise a metallic component together with various organic compounds - the simple elemental form of a metal is never used. There are several types of metal salts and soaps used to stabilise PVC for window applications.