Electric wrench is in the power supply or battery powered wrench, is a tool which is used to tighten the bolt. Mainly used in steel structure installation industry, special installation of steel structure high strength bolt, high strength bolt is used to connect steel structure contact, usually with bolts. Evenly as the strength should be soft and wrench. Definitely don't want to pull (with short, impulse force, because yank will produce an impulse, at the moment stop hard, screw or bolt may have turned her head. And pollutants can interfere with accurate torque value. If there are pollutants parts and screw hole, will not be able to have the correct torque value. , friction is a widespread phenomenon, but there are good and bad two aspects. The good thing is make the parts stay together; The bad aspect is, when tightened, it may lead to wrong result. A mechanic hand tight coupling force only % -% is used to tighten, and in many cases, there is % -% of torque is used to overcome the friction between bolt head and parts, along the bolt and screw hole spouse also generate additional thread surface friction. Therefore, when tightening bolts, should put all of the friction factor and other factors are taken into account. , on the screw thread damage or dysfunction of nut or bolt, attention should be paid to by injury need to how much additional torque, this additional torque to the recommended torque values.
