Screw Compatibility Table (Torx)
Coversion Table of Diameter
# 4 ＝ 2.84mm
# 5 ＝ 3.17mm
# 6 ＝ 3.50mm
# 8 ＝ 4.16mm
#10 ＝ 4.82mm
1/4″ ＝ 6.35mm
3/8″ ＝ 9.53mm
What is torque?
- Torque is the measure of a force’s tendency to produce rotation or torsion.
- The measure of Torque is now used for screw fastening using a tools like hexagon wrenches.
- Torque is defined as “Force” × “Lever-arm distance”.
For instance, when holding and applying force to a hexagon wrench inserted in a hexagon socket head bolt at 0.2m away from the center of the bolt with force of 10N, the tightening force is;
from the Formula : FXL=T (F: Force N, L: Lever-arm distance m, T: Torque N・m)
10N × 0.2m = 2.0 N・m It is also deduced from the Formula that F (force applied) necessary to obtain the tightening torque of 2.0 N・m with L:0.4m is 5N.
- ISO and JIS stipulate a guaranteed torque value for each size of hexagon wrenches within which they will not be broken, twisted, distorted in a hexagon shape or bent to the extent that they will become unusable. They also demonstrate the test method with a torque wrench.
- ISO and JIS specify that hexagonal wrenches shall not be broken or cause any irregularities such as twisting, deformation in the hexagon shape, or bending when used within proof torque values (ISO 2934,JIS B 41648).
-JIS specification shows proof torque values for each size as well as the test method using a torque wrench.
Maximum torque that human hands can produce
(test value of hexagon wrenches)
||L-Type Standard Size
||L-Type Extra Long
||L 2 (mm)
||L 2 (mm)
*The figures with (*) mark = The maximum torque human hands can produce exceeds the maximum value of hexagon wrench.
Directions for Use
Followings are the instructions and directions to prevent product damages or bends as well as to prevent accidents or injuries. We cannot guarantee the quality of our products and we are not responsible for any injury if the instructions and directions are not followed.
* Guaranteed torque value for our hexagon wrenches are in Torque Comparison Table.
Precautions for Products
Please use a product within the proper guaranteed torque value.
Fastening a screw with too much torque does not work well. It may end up wearing out the screw or damaging the bearing surface greatly, which would lead to a screw loose in time.
Regarding screws for a cutting turning tool, loosening a screw requires larger force than fastening it because of a thermal expansion after use. Please be aware that you might break a wrench or get seriously injured if you use a product with more than the guaranteed torque value.
- Use a product only for the purpose of turning a screw.
- Use a hexagon wrench that fits the screw hole.
- Do not use any pipe or ring wrench unless it is an attached accessory.
- Do not hammer a wrench or give it an impact torque. Rough use may reduce product life or break the product.
- Do not burr a slot.
- Do not use a deformed wrench. Since the strength of a twisted or bended wrench is greatly deteriorated due to the metal fatigue, using a deformed wrench even within the guaranteed torque value may cause a damage.
- Do not weight on the product for fastening. The wrench may slip and the metal fatigue may cause the bolt to twist off or the wrench to break.
- Since thin wrenches can be broken with a hand, overuse of a wrench is dangerous.
- Be careful about straining the products with small neck diameters such as taper head wrench and ball point wrench.
- Wear protective goggles. (when you cannot avoid overuse of a product)
- Clear the bolt hole. Chips in the hole disturb the wrench fit, which may result in a decrease of life duration of a bolt and wrench.
- Do not use a wrench for a worn-down bolt. The wrench may slip and it’s dangerous.
- Do not reprocess the chip of a wrench. Heat deteriorates the material and it may result in a damage or abrasion.
- Beware of electrical shock. Wrenches are metal. You will get an electric shock if you use a wrench when electricity is around.
- Since the hole of a Torx screw is shallow, insert a wrench straight. Otherwise, the wrench may slip and damage a screw and it’s dangerous.
- Tamper resistant screws are used to maintain the function of equipment, or to prevent accidents including gas leakage. Therefore, they must not be loosened. Please use a product only when you can make sure of the safety. We are not responsible for any accidents arising from what is explained above.
- Use a product that fits a screw hole.
- Some of the blister packs and mat boards for our products have angular corners. Be careful when you open a product especially for staplers.
- Do not use an impact wrench for an O-ring socket or a socket with no pins.
Wrench and Metal Fatigue
– Compared to other tools, a hexagon wrench is long and thin, and has a smaller cross-sectional area in relation to thread diameter. A large force will result in a flexibility and twist of a product.
Therefore, brute force as for another tool in a bigger size of the cross-section will lead to damages of a product.
The stress point at which a material, if subjected to higher stress, will no longer return to its original shape, is called “Elastic Limit”. Our ”guaranteed torque value” is based on the “Elastic Limit” according to ISO/JIS. Therefore, the stress at “Elastic Limit” can be considered to be the “guaranteed torque value”.
– Stress over the “Elastic Limit” ≒ “Guaranteed torque value” causes the mental fatigue to a wrench.
– “Guaranteed torque value” is the value before the mental fatigue is caused. Once the mental fatigue is caused to a product, the possibility that stress even within the “guaranteed torque value” may damage a product will be extremely high.
– Once a wrench becomes twisted or bended, the metal fatigue stays even if the wrench is brought back to its original form
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