· Customer needs:

M8x22 outer hexagon flange screw, the interference surface height of the product is 85mm;

· Working condition analysis：

1.Considering the height of the interference surface, select a screw driver with a telescopic head to meet the telescopic stroke within 50mm;

2. For the external hexagonal bolt, it is necessary to pay attention to the reverse rotation of the identification cap at the initial stage of tightening, and a multi-step tightening procedure can be set, first reverse and then pre-tighten (fast), stop the 0.1 S (release torque attenuation), and then final tighten (speed reduction), which can ensure the rhythm of 4S;

3. The effective and stable verification of this tightening strategy was put into use in the production line after 2 years.