Due to the fact that the curtain-wall is attached to the outer surface of the main structure, thus, to keep the curtain-wall smooth and even, the outer surface of the main structure (the base of curtain-wall) should be treated carefully under the help of some specific leveling devices like levels and theodolites. b) Fabrication of Column and Cross Beam After adjusting the base level, then installing columns and cross beams according to the design of basic joint points. For low-rise buildings, both expansion bolts and stay bolts could be used for the conjunction, however, for the high-rise building, only stay bolts could be used. If specific requirements mentioned, the pre-embedded parts are necessary. 2) Processing of ACP The tool used for grooving is called ??grooving machine??, which mainly adopts disc milling cutter because of its facility and convenience. As shown as the following picture, there are totally four kinds of milling cutters available in our company, and each of them will meet the different requirements of customers for the finished shapes of grooving respectively