A complete, ready-to-install insulated window assembly consists of two major parts: the insulated glass sub-assembly and the window frame sub-assembly. We usually refer to construction of the insulated windowpanes as “glass fabrication,” and the machines used to make them as “glass fabrication machinery.” When we are talking about the entire unit with the frame, we refer to the construction process as “window fabrication,” which is performed by “windows fabrication machinery.” In this article, we will cover the typical steps in window fabrication and the machines that make it happen.
What Processes and Machines Are Used to Fabricate Window Assemblies?
Windows are made in a variety of configurations combining fixed lights and casements or sashes (windowpanes that can be opened). A variety of design-specific hinges, locks and opening mechanisms are used. These windows may be framed in wood, metal (usually aluminum), fiberglass or uPVC.
- Window machinery for creating the frame and sash elements
Typically, a window fabricator will purchase near-net shape bars of framing material in a range of convenient, standard lengths. This material may be wood, aluminum, or uPVC (vinyl). Whatever its nature, the bar stock needs to be cut to the proper length and angle, and the stile and rail pieces (or frame pieces) joined. Depending on the production volume of a shop and its level of automation, these processes may be accomplished using:
- Hand tools such as a miter saw with appropriate blade followed by hand drilling holes for fasteners to join the frame pieces
- Frame cutting machines from semi-automatic to full CNC cutting machines which may perform more than one type of task, such as cutting joining angles, making finger joints in wood frames, milling decorative profiles, or preparing the pieces for later hardware insertion.
- For window shapes that have curved edges, a frame-bending machine can be used on uPVC or aluminum materials.
- Window machinery for joining the sash or frame pieces
Once the stiles and rails (or frame components) have been cut to the correct angle and length, the options for joining them together into a complete frame depend on the frame material:
- Aluminum-framed windows offer several possibilities. They can be screwed together using simple hand tools, if desired, but even for relatively low production volumes, most window manufacturers would use a corner crimping machine, which securely forces aluminum tabs from one frame rail into slots in the adjacent corner pieces. Crimping results in more attractive, stable joints than screws. Aluminum-framed windows can also be welded, but aluminum is not the easiest material to weld, and crimping is more cost-effective.
- Wood-framed windows are most commonly assembled by milling mortise and tenon joints with a milling machine, then placing them into a frame press, where they are assembled with glue and held tightly together until the glue has set. This process can be performed at any level of automation up to a fully outfitted CNC machine, depending on the fabricator’s needs.
- UPVC-framed windows are normally welded together using the hot plate welding technique, in which the frame pieces are held in place but separated by a hot metal plate, which melts the two surfaces to be joined. After sufficient heating, the heating plate is removed, and precisely calibrated clamps apply pressure to fuse the frame pieces. A corner-cleaning machine maybe incorporated into this process to clean up the resulting welding flash, or may be performed at a separate station.
- Window Machinery for Adding Hardware to Frames
If a window is to have the capability to be opened, closed, and locked, window manufacturers have to add the needed attachment points to both the inner and outer window frame, and then install the hinges, window cranks and locks. Some of this preparation work may be done by milling, routing and drilling machines before the frame components are joined, but the rest is done once the frame are assembled.
- Window Machinery for Laying Glass into Window Sashes
Glass panes, usually insulated glass, can be laid into the sashes by several manufacturing processes. They can laid onto beads of caulk applied by machine, then fixed in place with glazing blocks and finished with weather stripping beads. Different techniques apply to different sash and frame types. But as with every step in the process, highly automated, specialized machines are available to make each of these final steps in window assembly as efficient as possible.
- Window Machinery for Shipping Completed Windows
By the time a fully assembled glass window, sash and frame rolls off the conveyor belt of the last machine in the fabrication process, the manufacturer has made a significant investment in materials and labor – and he has a commitment to deliver a quality product to his customer! Completed windows are carefully stored on manual carts or machine-driven racks. Prior to shipping, wrapping machines encase windows in plastic film and cushioning layers to protect them from the rigors of shipping.
Conclusion
Engineers love the challenge of creating the right machine for every job. Manufacturing a complete sash-and-frame insulated glass window assembly is a methodical process with a lot of steps, and a lot of variations on those steps depending on the materials and designs chosen for an application. Window Machinery Direct is here to help the growing window manufacturing entrepreneur take advantage of the opportunity to find the perfect, high-quality, pre-owned window fabrication machinery at attractive prices. Contact us today for expert assistance!
Sources
Parts of casement and sash windows explained (salisburyjoinery.com)
