The existence of a vacuum chamber sets apart the vacuum insulated glass from other glass products. The vacuum insulated glass consists of two parallel flat glass plates that will be pressed inward under atmospheric pressure which will get the vacuum chamber between the adjacent glass panes gradually reduced or even disappeared. When the vacuum chamber is gone, the vacuum insulated glass is no better than ordinary dual-pane glass. Its performance will also be greatly compromised. In order to ensure the presence of the vacuum chamber, the spacers are placed between the two glass plates as the support.
There are stringent requirements for the selection of spacers:
1. It is required to minimize the volume and overall number of spacers so as not to increase thermal conductivity and reduce the transparency of glass;
2. If the volume of the spacers is too small, the atmospheric pressure will create a concentrated load over areas where the glass plate coming into contact with the spacers, resulting in easy breakage of glass due to the tensile stress increased in the glass above the spacers;
3. The shape of the spacers: Currently, most spacers are cylindrical. They may also be square-shaped, oval, linear, or grid;
4. The spacers can be made of stainless steel, tungsten carbide steel, chromium steel, aluminum alloy, nickel, molybdenum, tantalum, ceramic, etc.
The distances between the spacers are also subject to certain criteria:
In general, the distance between spacers is determined according to the parameters such as the type of glass, thickness, type of spacer and diameter, etc. before the production. In the event of displacement of spacers, the permanent residual stress in glass will increase, leading to an increased probability of breakage of the vacuum insulated glass in future applications. In severe cases, it can directly cause the glass substrate to contact each other or crack.
In terms of spacers placement, at present, most enterprises do it manually. The approach requires more investment in manpower and is labor-intensive, less accurate, easy to cause pollution, and extremely low inefficiency, which is difficult to carry out In context of this situation, LandGlass invested a large amount of manpower, time, and money to develop its automated spacers placement solution during the R&D of LandVac. This automated placement device can place spacers according to the pattern and distance set in the operation control program, eliminating the problems associated with manual operation. It provides a perfect solution to the spacer placement problem in the production of vacuum insulated glass and greatly improves the yield and quality of the vacuum insulated glass.