Tempered glass cannot be cut with a grinder, if you try to cut tempered glass, no matter what polishing machine you use, even if it is a diamond disc, the tempered glass will break, because the tempered glass in its composition is designed to work that way.
Although it may not seem like it, the grinding machines when rotating the disc at a high speed produce a lot of vibrations, this, apart from the attempt to compromise the tempered glass structure, will cause the tempered glass to break rather than cut.
Tempered safety glass can not be processed either on the edge or on the surface after the toughening process. Possible processing such as grinding/polishing edges as well as drilling holes, corner cutouts, etc, but it cannot be cut.
Provided you have the necessary experience, cutting glass is usually not a difficult task. Any glazing company can process and cut glass of any type, shape, and color, with one exception: If you are asked to cut or process tempered glass, all professionals will refuse to do so, because, due to its nature, tempered glass is not suitable for cutting.
Why can’t tempered glass be cut with a grinder?
Tempered glass is also known as toughened safety glass or safety glass. In reality, as its name might suggest, it is not extra hard or stable glass, but safety glass that breaks into thousands of small pieces without sharp edges when shattered.
This quality of tempered glass is generally used by the automotive industry to manufacture the side windows of cars, thereby reducing the risk of injury from broken glass in the event of an accident.
Tempered glass is produced by intense heating and subsequent cooling with cold air, resulting in differing stresses in the glass, which ensure that the glass is relatively safe to break in the event of breakage.
Tempered glass is about seven times harder than plain glass and is particularly stable against blunt forces such as fist blows. In contrast, minor damage caused by sharp objects quickly shatters the glass. Therefore, it is not possible to cut or drill through tempered glass.
Once the tempered glass is finished, it cannot be cut, drilled, or shaped. Since tempered glass is specially designed to distribute pressure, it will crack and break if the glass stress breaks. Therefore, any tempered glass unit must be cut to size and shape before the tempering process takes place.
If the tempered glass breaks, shards of glass will break off, which could be very sharp and dangerous. However, the internal and surface tension of the glass pane is created during the hardening process to increase its strength and durability.
This also ensures that if the glass breaks, small, harmless shards of glass will break.
How do you recognize tempered glass?
Tempered safety glass must be marked, this is done using an ESG stamp in the glass corners.
Labeling is not mandatory for laminated safety glass, but in most cases, the manufacturers attach a corresponding stamp or sticker to the glass pane.
This type of glass cannot be recognized in the undamaged, installed state. A pane that has not been installed can be identified by the profile of the outer edges.
One way to recognize tempered glass in a practical way is a simple trick: hold a flame in front of the glass. If the flame reflects twice on the glass, it is most likely tempered safety glass.
How to cut tempered glass?
If you want to cut tempered glass, just return it to the furnace and heat it to a temperature above 600 degrees to remove the stress, and then you can cut it.
There is also the possibility of laser cutting the tempered glass, but this is a job that only qualified professionals can do.
Alternative safety glass to tempered glass that can be cut
While tempered glass cannot be cut, alternative types of safety glass can be cut. The most common types are laminated safety glass and wired glass. Depending on the intended use, refractory borosilicate glass can also be used.
Laminated safety glass
In contrast to ESG, so-called laminated safety glass (VSG), which is mainly used for car windshields, balcony glazing for fall protection, and as a basis for burglar protection, can be cut.
It consists of at least two glass panes pressed with a highly tear-resistant film, which makes it very robust is. To cut it, a glass cutter is needed, with which the glass is cut and broken in a controlled manner along the cutting line.
The best way to cut the sheet is with a cutter or scissors. Under no circumstances should it be broken, otherwise it could tear the panes of glass and lose its safety effect.
Wired glass is fused glass inlaid with fine wire, which is quite stable. It is used, among other things, for glass door infills and for glazing canopies and balconies.
Thanks to the wire insertion, the resulting glass splinters are held together in the event of breakage, which considerably reduces the risk of injury. However, unlike conventional flat glass, it is not very rigid and therefore not suitable as protection against break-ins. It is also susceptible to temperature fluctuations.
Unlike tempered glass, wired glass can also be cut: For this purpose, in addition to the glass cutter, an angle grinder is required, with which the pieces of wire can be cut in a controlled manner after the glass has been broken.
Borosilicate glass or Jena glass
This extremely temperature-, fire- and chemical-resistant glass is used in the chemical industry, in lighting technology, but also in the household, e.g. for various heat-resistant kitchen utensils and as a window for space heating devices.
The high-temperature resistance is due to the high quartz sand and boric acid content of the glass, which means that there is little thermal expansion. To cut this refractory glass, a diamond-tipped glass cutter is usually required.