Raw materials. All vinyl products are made from combinations of vinyl resin and various additives which give these products their particular properties. For more information on the vinyl resin process, see general vinyl section. Every formulation is different, and most are proprietary. Most vinyl window formulations are made up of about 80 percent vinyl resin. Some of the additives commonly used in vinyl window and door profiles include:
- Stabilizers, which help minimize the degradation of the vinyl during exposures to high temperatures in the extrusion process. They also help prevent cracking, splitting, pitting, peeling or chalking.
- Pigments to provide consistent color throughout the product and to screen or absorb UV radiation, which would otherwise cause rapid degradation of the product.
- Modifiers to provide impact properties, or resistance to cracking or breaking during the fabrication processes, including sawing, routing and punching. These additives also improve resistance to general abuse during transportation, storage and installation
Processing/fabricating. Once the additives have been combined with the resin, the resulting material is called vinyl compound. The vinyl additives are mixed evenly throughout vinyl compounds, which ensures consistency of color, strength and UV resistance. Once compounded, these additives are chemically combined or locked into the structure of the profile material, minimizing any loss of properties or discoloration. The compound is then softened or melted, mixed and forced through a uniquely shaped opening or die in a process called extrusion.
These extrusions, which form the basis for a vinyl window assembly, are shipped to a window fabricator on pallets in 16- or 20-foot lengths. The window fabricator then cuts the bulk lengths to the specified dimensions of the window. Machines cut the profiles to accept the appropriate hardware and prepare the components for assembly. The frame and sash components are most often fusion-welded together to form air- and water-tight corners. The remainder of the assembly entails installation of locks, keepers, balances, operators, weatherstripping and insulated glass, after which the completed window is ready to be shipped to the job site.