How to Use Flat-head Screws

Most of the head screws are used in the need to install, the surface of the part can not have a raised place, the fastened parts and thick and thin two, so-called thick, that is, the thickness of the tight part is greater than the thickness of the head of the head of the sink screw, after the screw is tight, there is still a part of the screw thread did not enter the threaded hole. In this case, the head screw strained. Usually there is also a situation, the thickness of the fastened part is less than the height of the head of the head of the sink screw, which is common in mechanical equipment sheet metal parts, such as the chassis of the sheet of the joint with the door and box body; Due to the small thickness of the part, tighted sheet metal parts, screw through the hole completely become a conical hole, in this case, when the head screw is tightened, the screw head is not a tapered clasp sheet metal, but the bottom of the screw root and the top of the threaded hole squeeze, although feel the screw is tightened, but the sheet metal piece is stuck rather than tightened, in this case, feel tight, but the sheet metal is not tightened. This is a very common situation.

Again, the reason for the processing: the head of the head of the head screw is 90 degrees cone angle, usually the top angle of the newly purchased drill bit is 118 degrees-120 degrees, some untrained workers do not know the angle difference, often directly with 120 degrees of drill head expansion hole, which causes the head screw tight is not the head cone hard, but the bottom of the head of the head hard, this is the so-called screw head tight one of the reasons.