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What is Torque?

From Mountz, Inc.
 

 

(Diagram A) As the nut and bolt are tightened, the two plates are clamped together. The thread angle in the bolt converts the force applied into tension (or stretch) in the bolt shank. The amount of the tension created in the bolt is critical.

A bolt tensioned properly works at its optimum efficiency and will resist coming undone. However, if the tension is too low, the nut could vibrate or work loose. If the tension is too high (overstretched), the bolt could break. Ever y bolt has a correct optimum torque/tension figure for each fastening application. It is important to have these figures available so that the end product will be safe, efficient and economical.

Another factor that affects applied torque when using torque wrenches is if it is "length dependent," which means that the actual torque applied to the fastener varies if the hand position on the wrench is varied (even if the wrench is preset). This occurs if the pivot point of the wrench mechanism is not coincidental with the point of application of torque.

Product Announcements
Stress Indicators Inc. - DTI SmartBolts
Critical bolted joints often require exacting tightening procedures to establish the optimum clamp load. While tightening by torque wrenching methods is quick and easy, extensive tests have shown that... (read more)
Mountz, Inc. - TorqueMate Electronic Torque Wrench
The TorqueMate is a microprocessor controlled electronic torque wrench. The electronic wrench enhances process reliability through complete monitoring of the fastening and assembly process with full... (read more)
Mountz, Inc. - TB (Break-Over Torque Wrenches)
The TB torque wrench ensures proper torque is achieved with its break-over design. It breaks-over at 90ยบ once the preset torque is reached, which eliminates overtorquing. The versatile wrench features... (read more)
Mountz, Inc. - Cap & Tube Tightening Torque Wrench
Mountz, Inc. introduces new torque wrench designed for cap, SMA connector and tube tightening applications. The head of the wrench can used for round knurled or non-knurled nuts where gripping to... (read more)
Mountz, Inc. - CLD (Pneumatic Torque Multiplier)
CLD Pneumatic Torque Multiplier provides precision tightening and loosening of all heavy duty fastening connections. Shuts-off when pre-set torque is achieved. Non-impacting and operates at a smooth,... (read more)
Mountz, Inc. - TorqueMate Digital Screwdriver
The digital screwdriver ensures product quality, cost savings and a reduction in overall production failures through complete monitoring of the fastening and assembly process with full data collection... (read more)
Mountz, Inc. - Screw Counter
The Scout is like putting the eyes and ears of a Quality Control Manager where they are needed most; right on the assembly line. The Scout screw counter prevents costly screw fastening errors on the... (read more)
Mountz, Inc. - Clean Room Torque Screwdrivers
Clean Room Torque Screwdrivers are manufactured to comply with Class 100 Clean Room standards and are polished and sealed with a PTFE impregnated anodized coating that creates a tool nearly 40 times... (read more)
Valley Forge & Bolt Mfg. Co. - Constantly Monitor Clamp Load on a Bolted Joint
Valley Forge & Bolt Manufacturing Co. is a manufacturer of hot forged standard and special fasteners with the capability to machine and roll thread to customer specifications. (read more)
 
Topics of Interest
Torque is a 'turning' or 'twisting' force and differs from tension which is created by a straight pull. However, torque is used to create tension. How? As the nut and bolt are tightened the two plates... (Read More)
Torque wrenches are often regarded as a means to improve control over bolt preload in comparison with hammer-tightening methods. However, as indicated in Table A7.19, significant variation in... (Read More)
In the world of engineered components, let's face it, fasteners aren't the first thing engineers think about. They're not exciting, they're not sexy. They're commonly treated as routine. But choose... (Read More)
The function of a bolt is to provide a clamp load or preload (Fp) to sufficiently compress and stress the gasket and resist the parting forces exerted by the hydrostatic end force and other external... (Read More)
Bolting material for cast-iron flanges is listed in ASME B16.1. Generally, ASTM A307, grade B material is suitable. For steel flanges, acceptable bolting material is listed in ASME B16.5. (Read More)