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Do you know these correct positions of tightening torque?

March 25, 2024

Q1: Due to high beat requirements and fast speed, the final torque is not real. How to verify the final torque after tightening?
First of all, there is a contradiction between the tightening quality and the beat, but we all need to optimize the beat while ensuring the quality.
Second, we tighten in a step-by-step manner throughout the tightening process, after pre-tightening, screw in at a high speed, and then at a slow speed for final tightening.
How can the final tightening torque be verified? In our field tightening quality control process, we test the final tightening torque by checking MNA1 (retightening torque).


What is retightening torque and how to detect it?
As the name suggests, the retightening torque is the torque obtained by applying a certain Angle to the bolt using a tightening wrench after tightening. The resulting torque MNA1 is compared with the torque on the tightening tool, and its tolerance range is divided according to the material of the connector.


Q2: The site is also tightened in a step-by-step manner, but some torque exceeds the final torque, what should I do?
Tightening is carried out in a step-by-step manner on site. The first step is to identify the tools and bolts. The second step is to tighten the bolt to 3nm at high speed, and finally tighten it at low speed to the torque required by the process (torque + Angle), but after pre-tightening, some torque exceeds the final torque.


How many revolutions per minute is the high speed set for pre-tightening? How many revolutions per minute is the low speed set?
The high RPM reached 1000 RPM. In the tightening tool at 1000 RPM, its motor brake in fact many times is not brake, this step is set to the torque control of 4Nm target, the final torque will exceed the set torque of 4Nm, may also exceed the final control torque.
Here, a suggestion: set the target of the high speed step to Angle control. The set target Angle is calculated by the matching length of the bolt connection. This step is completed before fitting, and then tightened to fit at a slightly lower speed, and finally tightened to the target process at a low speed.