Determining the precise torque specifications for your manufacturing processes is crucial for ensuring product integrity and operational efficiency.
In many applications, a joint's reliability hinges on a bolt's ability to clamp parts together effectively. Proper clamping prevents relative motion between joint components and leakage from gasketed joints. However, measuring a bolt's clamp force directly, especially in production assembly settings, can be challenging.
For more comprehensive information on these topics, please watch our webinars, “How Friction Impacts Torque and the Fastening Process" and: "A Guide to the Fundamentals of Torque Control."
Controlling Clamp Force Through Torque
Torque control is a popular method for indirectly controlling a bolt's clamp force. This method regulates the applied torque to achieve the desired preload, which refers to the initial clamp force generated by the bolt.
Relationship Between Torque and Preload
A relationship exists between the torque applied to a bolt and the resulting preload. However, friction plays a significant role in converting torque into preload. Typically, only 10% to 15% of the torque stretches the bolt, while the rest dissipates as friction, with approximately 30% in the threads and 50% to 55% under the nut face. Variations in friction due to different bolt surface finishes can significantly affect preload.
Effect of Bolt Design on Torque Requirements
The torque required for different bolt designs can vary. For example, a socket head screw may require different torque compared to a standard hexagon bolt of the same size. This difference is due to the larger bearing face of the standard bolt, which dissipates more torque between the nut face and the joint surface.
Stresses in a Bolt
When tightening a bolt, it experiences direct (tensile) stress from stretching and torsional stress from torque acting on the threads. These stresses are combined into an equivalent stress compared to the bolt's yield strength. Typically, an equivalent stress of 90% yield is used to effectively utilize the bolt's strength while allowing a safety margin for service loading.
Advantages of Equivalent Stress Approach
Using an equivalent stress approach offers advantages over assuming a direct stress and preload value in the bolt. For instance, high thread friction values result in higher torsional stress and lower preload, while low thread friction values lead to higher preloads.
Practical Considerations
It's important to note that the information provided guides engineers in determining theoretical torque values based on selected friction values. However, practical tests should be conducted to validate torque values derived from formulas before they are applied in real-world scenarios.
Need Help figuring out Where to Start?
Determining the precise torque specifications for your manufacturing processes is crucial for ensuring product integrity and operational efficiency.
At Mountz Torque, our application specialists are ready to assist you in conducting comprehensive torque studies tailored to your needs. Our team can provide guidance and recommend equipment, such as torque analyzers and sensors, for your team to determine torque value requirements.
As part of your research and development evaluation process, your team should perform destructive tests on the material and fastener to be joined using a calibrated torque measuring instrument.
The goal is to find the fastener's yield point and determine the application's torque specification.
With years of expertise and a deep understanding of torque applications across various industries, our specialists collaborate closely with manufacturers to identify the optimal torque settings for their unique applications. Through meticulous analysis and testing, we provide invaluable insights that enable you to achieve precise and consistent torque results, ultimately enhancing product quality and reliability.
Whether you're seeking to establish torque parameters for assembly lines, quality control procedures, or specialized manufacturing processes, Mountz Torque offers unparalleled expertise and support at every step. Trust in our commitment to excellence as we empower you to optimize your torque applications and drive success in your operations.
The Mountz Advantage
At Mountz, we understand the importance of human customer support. That's why our experienced team takes the time to understand your application requirements comprehensively. Drawing on our extensive industry experience, we offer personalized recommendations to streamline your assembly processes and enhance efficiency.
Mountz stands out in terms of durability. We know that preventing downtime is paramount to your success, so our tools are built to last. Rigorously tested to meet the highest standards, our products deliver unmatched reliability, ensuring your operations run smoothly without interruption.
Trust Mountz for industry-leading torque solutions designed by experts, backed by exceptional customer support, and built to withstand the demands of your assembly processes. Contact us today and experience the Mountz advantage firsthand.
