Everything that is assembled on a manufacturing line is put together using some sort of fastening strategy, and torque is a large part of these strategies. Consider the measurement of torque and angle and the role it plays in how fasteners hold sophisticated mechanical devices together. The usual way that engineers and other assembly workers deal with torque and angle is through a torque tool that is equipped to measure angle.
What are Torque and Angle?
Torque is a simple measure of the rotational force applied to a fastener. It is determined by multiplying the force required to turn the fastener by the point of the application’s distance from the fastener. If too little torque is applied, then the fastener will not hold to specifications. If too much is applied, then the fastener or the substrate may deform, fracture, or fail. Measuring the angle allows the engineer or technician to turn the fastener the proper number of degrees to achieve the right fastener stretch. From an engineering standpoint, torque and angle provides a controlled way to measure and monitor quality during the fastening process in order to detect any component failures immediately.
The diagram below can help explain the logic behind torque and angle:
The proportional limit denotes the final point where stress is directly proportional to strain and the upper limit of elasticity—where material can “snap back” into shape when stress is released. Although, it should be noted that a fully tightened fastener will remain under tension. Below proportional limit tightening and loosening is infinitely repeatable since the fasteners and substrates retain their shape. The material does retain some elasticity above this point, but it marks the beginning of plasticity where the material will start to change dimensions. This will increase until the elastic limit where the material begins to yield and plastic deformation permanently alters the shape of the fastener or the substrate.
Torque and angle tightening strategies usually target the area between these two points. The plasticity of the bolts in this range helps ensure that the tension on the substrate is high and that components are clenched tightly together. However, there are special types of fasteners called stretch bolts that are designed to go beyond the elastic limit and permanently deform. They cannot be reused and are instead replaced for every fastening application. The most common place where torque angle and stretch bolts are encountered is in automotive head repair, where a good seal is vital to ensure proper airflow, fuel air mixing, and exhaust evacuation. They can also be encountered in other applications that involve gaskets and fluid or airflow sealing. Due to the importance of the situations where they are used, angle torque wrench accuracy is a crucial concept to understand.
Torque and Angle Sensors Ensure Accuracy
The usual way to apply torque angle is to torque a fastener to specifications with a click wrench, cam-over wrench, or break-over wrench. Then, a torque angle gauge—also called a degree wheel—is placed between a wrench with a ratchet head and the socket, and the fastener is turned to the specified angle. Some newer digital angle torque wrenches can determine not only when a specified torque setting has been reached but also offer the ability to measure torque angle on a digital display.
In repair shops, an issue that has come up with digital torque angle wrenches is that, while it does remove the extra step of having to grab and attach a torque angle gauge, it also adds the step of changing modes, and depending on the model, a need to lay on a level service to allow for the angle torque wrench to calibrate for torque plus angle mode. It is possible that accuracy could suffer due to a worker lacking a steady rest in an industrial environment or due to hurrying through the calibration. Delays could also occur due to confusion about how to navigate menus. In manufacturing and along assembly lines, torque angle wrenches are usually operated by automated systems, and there are various types of torque tools that can serve as angle torque wrenches with the proper controllers. In either case, torque analyzers and torque sensors are important for ensuring the accuracy of an angle torque wrench and are potentially useful for stage-by-stage assembly line design.
Torque analyzers and torque sensors provide a highly accurate measurement of a torque wrench’s output. Many of them have a torque plus angle setting that offers an accurate readout of the tension of a bolt tightened to torque specifications and then tightened to a specific angle. This is data that can be used to ensure that angle torque wrenches are properly calibrated and are working as intended, and they can provide the measures needed to control the quality of output by conduction audits with a dial torque wrench. It can also provide mechanical engineers with the testing data they need to design quality products, design the production lines that assemble them, and improve them over time.
Mountz, Inc. supports optimal torque control, quality control, and repair with a full range of torque analyzer and torque sensor equipment to measure the output of torque and angle wrenches. To see our full range of products, shop our store. Contact us anytime to ask a question. To inquire about price, request a quote. If you’d like to see our equipment in person, schedule an appointment.