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1 Introduction
The TCV/FM Switch Wrench System is designed to assist the manufacturer in closing sev-
eral gaps in the quality system that have hindered their quality improvement efforts. The
key capabilities this system enables are:
1. The ability to integrate manual torque wrenches into the automated line control system.
2. The ability to attain control of the actual torque wrench use process, not just the
wrench calibration process.
3. The ability to provide rapid and effective training in proper torque wrench use through
reinforcement of proper technique with every cycle of the wrench.
1.1 Control Concepts
The TCV works with the FM Switch Wrenches to bring systematized control to the use of
manual torque wrenches. The control is applied as follows:
1.
There are three ways to use a clicker-type torque wrench. When used properly, a steadi-
ly increasing force is applied until the wrench clicks and the pressure is immediately
released and the tool resets. One improper use technique consists of applying force too
quickly (”jerking” the wrench). The other improper technique is to continue to apply force
after the click and overtorque the fastener.
2.
When the correct technique is used the torque wrench spends a certain amount of time
in the “clicked” position. When the wrench is used too quickly it spends less time in the
clicked position. When it is rotated past the click it spends more time in the clicked posi-
tion.
3.
The FM Switch Wrench is a preset clicker-type torque wrench. The torque is preset using
a torque tester to assure the wrench is accurately set. The torque setting is then locked
in.
4. The FM Switch Wrench has a timer that measures the duration of a click (cycle) of the
wrench. once the wrench has been accurately adjusted on the tester, variation in tech-
nique can be controlled by measuring and controlling the duration of the click.
5.
An experiment is conducted to determine the correct use of the torque wrench (duration
of time in the clicked position) to obtain the correct torque on the joint. The accurately-
preset torque wrench is used to tighten the fastener(s) on the joint and an indicating
torque wrench is used to check the torque after the tightening. The experiment deter-
mines the minimum and maximum click duration to attain proper torque.
6.
The minimum and maximum duration of a proper click is programmed into the TCV.
[Time Minimum or TMIN and Time Maximum of TMAX]
Summary of Contents for TCV
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