I have serious problems with HST, because all my glass plates break during the process (every 100 plates 80 are broken). The plates are 1500 x 2500 mm, glass tickness is 12 mm, the holes are D=12mm and are 24mm distant from the long sides. There are total 8 holes. At the corners the holes are 160mm and 30mm distant (from the edges). During the tempering process all is OK. In the HST process during the cooling phase the glass break.
I don't know if the problem is the tempering process or maybe the position and the diameter of the holes.What do you suggest me?
Thanks in advance
Robert from Italy.