How to choose torque measuring devices and torque screwdrivers

TOHNICHI JAPAN'S TIGHTENING AND FORCE MEASUREMENT SOLUTIONS

Things to know before using a torque tool Tohnichi

Tohnichi torque wrench

Nowadays, there are many methods to assemble machine parts together such as gluing, welding, pressing, etc. But the method of using bolts and nuts is still used more because of its convenience, economy and ease of operation. But how to tighten properly, what are the benefits of using a torque wrench or torque screwdriver? How to choose the right torque tools for your work requirements. The following article will help you answer the above questions.

1. What is Torque?

Torque is a physical quantity generated when a force F acts perpendicular to a lever arm of length D.

T = F x D (Torque = Force x Distance).

Example 1: D = 1 m, F = 100N, T = 100 Nm

Example 2: D = 2 m, F = 100N, T = 200 Nm

2. The importance of Torque control

Nowadays, there are many methods to assemble machine parts together such as gluing, welding, pressing, etc. But the method of using bolts and nuts is still used the most because of its convenience, economy and ease of operation.

One problem that arises in assembling parts using bolts and nuts is the tightening force, also known as Torque. Over-tightening will reduce the durability of the bolt and nut, which can lead to destruction and damage to the parts. If the tightening force is too small, the joint becomes less durable and is prone to peeling off during operation/use.

For the above reasons, the Torque Tool was born. With an accuracy of ±4% (according to ISO6789 standard, some other brands have higher accuracy of ±3% such as Norbar Torque Tool.

3. Units used in force instruments (Torque)

Unit to convert	SI units		British units			Metric Units
Unit to convert	cN.m	Nm	ozf.in	lbf.in	lbf.ft	kgf.cm	kgf.m
1 cN.m =	1	0,01	1,416	0.088	0,007	0.102	0,001
1 nm =	100	1	141.6	8.851	0.738	10,20	0.102
1 ozf.in =	0.706	0,007	1	0.0625	0,005	0.072	0,0007
1 lbf.in =	11.3	0,113	16	1	0.083	1.152	0.0115
1 lbf.ft =	135.6	1.356	192	12	1	13,83	0.138
1 kgf.cm =	9.807	0.098	13.89	0.868	0.072	1	0,01
1 kgf.m =	980.7	9.807	1389	86.8	7.233	100	1