When it comes to forced convection tempering furnace, we have to mention low-E glass. Low-E glass, also known as low-radiation glass, is a film product consisting of multi-layer metals or other compounds coated on the surface of glass. When ordinary transparent float glass is tempered, the low temperature of glass is required to reach 40-50 C above Tg. Because the low-E glass coating has high reflectivity to infrared radiation, the heat absorption rate of the glass surface is reduced, and the heating temperature can not exceed 630 C. In order to ensure the tempering temperature of the glass plate, the heating time in the furnace should be prolonged, which will result in low-E glass. Low-E glass has the characteristics of film surface, which affects the basic properties of glass due to the oxidation or even combustion of film surface, the decrease of surface quality and the destruction or even loss of basic functions of film surface after long-term exposure to high temperature.

       In addition, another problem still exists when tempering low-E glass in ordinary radiation heating furnace: the upper and lower surfaces of glass are not uniformly heated, the temperature difference is too large, warping occurs, and the required temperature curve is not easy to form. Roller mark and white fog are easy to appear on the lower surface of warped glass in tempering furnace, and the flatness of glass decreases. When making sandwich glass, film thickness increases and cost increases. 。 Although some results can be achieved by adding the upper auxiliary convection tube, the injection of compressed air at room temperature into the furnace results in a decrease in thermal efficiency and an increase in energy consumption of the FRP furnace.

      Due to the limitation of the equipment itself, it is easier to produce product defects when tempering low-E glass with ordinary radiation heating furnace, such as obvious concentration of stress spots in finished glass, excessive flatness, and adverse phenomena such as excessive surface stress, increasing the self-explosion rate of nickel sulfide, etc. At the same time, the operation level is very high, the product quality is not easy to control and the production efficiency is low. The advantage of forced convection furnace is that it is used to process coated glass. In addition, we can also find that the production efficiency and product quality of forced convection furnace are obviously better than those of ordinary radiation furnace when processing ordinary white glass. Combined with the requirements of energy saving and emission reduction and green building materials, energy-saving glass is the inevitable trend of glass processing development in the future, so in general, we would recommend that customers choose forced convection tempering furnace instead of radiation furnace.

       Secondly, let's talk about the difference between full convection glass tempering furnace and upper half convection glass tempering furnace. The upper half convection tempering furnace is actually an intermediate product between full convection tempering furnace and radiation furnace. The upper part uses air convection to heat the upper surface of glass, and the lower part adopts traditional radiation heating method, which can solve the low-E glass surface radiation rate. The problem is that some low-E glass can be processed. Suitable for customers with low-E glass processing specifications and small orders. The convection device is also added to the lower part of the fully convective steelmaking furnace, which strengthens the heat transfer in the lower part. It solves the problem that the convective heat transfer is only used in the upper part of the tempering furnace when processing large plate glass and coated glass less than 4mm, but the heat transfer rate of the upper surface of the glass is obviously accelerated, the heat transfer of the lower part is relatively slow, and the defects of spherical bending are easy to occur. It can make the upper and lower surfaces of the glass heated synchronously, so the heating quality of the glass is better and the production efficiency is higher. Full convection tempering furnace is suitable for enterprises with more than 30% processing capacity of coated glass or many kinds of glass processing.