1、 The drilling is preferred for the hole making of steel structure. When it is proved that the quality, thickness and hole diameter of some materials will not cause brittleness after punching, punching is allowed.Drilling is carried out on the drilling machine and other machinery, and steel structure members (parts) of any thickness can be drilled.The advantages of drilling are less damage to the wall of bolt hole and better quality.

2、 In steel structure processing and manufacturing, punching is generally only used for punching non-circular holes and thin plate holes. The hole diameter of punching must be greater than the plate thickness. Punching is allowed for all common steel structure parts with thickness less than 5mm, and punching is allowed for minor structure parts with thickness less than 12mm. On punching holes, no subsequent welding (groove shape) is allowed, unless it is proved that the material retains considerable toughness after punching, then welding can be carried out.In general, when the hole to be punched is expanded, the punching must be 3 mm smaller than the specified diameter.

3、 When the processing accuracy of Guiyang steel structure is high, there are many layers of plate stack and many holes of the same kind, the method of drilling mould holes or pre drilling small holes and expanding holes during assembly can be used. When the plate stack is less than 5 layers, the diameter of pre-drilling small holes is less than the first class of nominal diameter (3mm), and when the plate stack is greater than 5 layers, it is less than the second class of nominal diameter (6mm).

4、 When drilling, the flat bit is often used, and the point bit is used when drilling holes.When the stack is thick, the diameter is large, or the material strength is high, the group drill bit that can reduce the cutting force should be used to facilitate chip removal and reduce the wear of the drill bit.

5、 The long hole can be processed by oxygen cutting between two ends of the hole, but the length of the hole must be greater than 2 times of the hole diameter.

6、 High strength bolt holes shall be drilled when steel structure parts are drilled.