It is important to prepare the wood of window frames and sashes well for coating. On the one hand it is about the visual appearance of the window. A smooth surface also improves the weather resistance of the finished surface.

Sanding the individual parts before gluing

Machine sanding of the profiled longitudinal sides of the window components is only possible before gluing. For this purpose, a profile sanding machine is used, which is specially designed for this purpose. If the longitudinal profiling is done in particularly good quality, mechanical profile sanding can also be omitted. This requires the use of high-quality machines and tools with good sharpness.

Sanding of window sashes and frames after gluing

At the latest after gluing, the wood surface must be prepared for lacquering: Any planing marks must be removed. In addition, any glue that has escaped at the corner joints must be removed. After gluing, however, only the flat facing sides can be machine-sanded - sanding the profiles is then no longer possible.

A wide-belt sanding machine is used for sanding the facing surfaces (inside and outside) of standard windows and small window combinations. A brush sanding machine serves the same purpose, but also covers deeper lying areas of the surface. Hybrid concepts with brush and sanding belts are also offered. The size of the windows that can be processed in this way is limited by the working width of the machine.

For larger windows and window combinations, all that remains is sanding by hand with an orbital sander.

Profile sanding machine

Often the profile of the long sides of all window components is sanded before gluing. All individual parts pass the profile sanding machine in longitudinal direction. Through a combination of sanding belts, lamella rollers and discs, the parts are sanded from all four longitudinal sides ready for lacquering. Top models detect the width and profile of the parts without contact and adjust themselves automatically accordingly.

Wide belt sanding machine

Wide belt sanding machines guarantee a very good surface quality and are efficient. Models with different numbers of belts are available. They can only sand the flat facing surfaces; the maximum possible width is limited.

Brush sanding machine

The material is removed here by several brushes moved along and across the window frame or window sash. A motor-driven height adjustment as well as speed control of the individual aggregates enables a flexible adaptation to different part geometries.

Orbital sander

Orbital sanders differ mainly in the removal rate, weight, service life and the quality of the dust extraction.

Gluing of window frames and sashes

During gluing, the corner joints of the window frames and sashes are assembled. Gluing is done manually or automatically, as well as the insertion of connecting parts (dowels or screws). A typical window corner contains four dowels; an element with sash and frame has eight corner joints, i.e. 32 dowels (which makes 64 drillings). In a small production facility, the dowels can still be glued and inserted by hand. For a larger daily production of window elements, a dowel inserting machine is the more economical method. Then the window sash or window frame is brought into its shape in a press and held for a certain time until the glue has hardened sufficiently.

Dowel inserting machine

The dowel inserting machine apllies the correct amount of glue and inserts the dowels.

Frame press

The press seals the joint tightly and guarantees that the raw window is perfectly square. Simple variants are the manually operated frame press or also a universal table press. In mass production, hydraulic frame presses that can be automatically operated are usually used.