In the first part of our Expert Hub series on seating control, our assembly expert Michael Laue describes what happens in a bolted joint after the seating point has been reached and what errors may occur.
This second article in the series deals with the specific benefits to customers of tightening process with seating control and the assembly applications for which this economical, reliable tightening strategy is especially well-suited.
Expert Hub: Mr. Laue, in the first part of this article, you described the many errors which may occur during the tightening of joints. On this basis, seating control is suitable for a wide variety of tightening operations. Could you give us some practical examples to demonstrate the benefits to users?
Michael Laue: Frequently, we use this strategy to provide support to customers faced by fluctuating hole diameters in plastic or diecast components. The components may be installed in equipment ranging from mobile phone housings to headlamps and rear lights or assemblies for medical ventilation systems.
[The Covid pandemic has led to tremendous demand for medical devices such as ventilation equipment. As a result, and also in view of the new EU Medical Devices Regulation in force since May 26 manufacturers have urgently needed support to meet the requirements of the MDR.]
Tightening strategies based solely on torque control cannot apply the clamping force required to the joint as precisely as required because the seating point may be reached at different torque levels.
With seating control, these factors can be detected and compensated for. Irrespective of the reached torque value, the seating point is detected and the required clamping force is applied to the joint by using a defined angle. This approach ensures constantly high quality and customers can depend on a safely assembled product. In addition, this approach is often considerably more economical than minimizing production tolerances on plastic and diecast parts.
Expert Hub: So this beneficial approach ensures greater process security in addition to saving costs. How do you achieve this objective?
Michael Laue: In order to define the optimum settings for the customer’s individual joint, a tightening analysis is required. For this purpose, various tightening tests are carried out on genuine new components supplied by the customer. Our objective is to develop the best possible tightening parameters for the tightening process analyzed and to confirm the functionality of these settings using verification measurements.
We start by requesting the customer to send us 10 new, genuine parts which we can use for seating point detection tests in connection with the proposed tightening process. If this initial investigation confirms that the procedure is feasible, we then offer the customer a full analysis.
Expert Hub: You had already mentioned a few components on which your laboratory conducted tightening analyses with a view to optimizing assembly. Could you give us some information on other products or sectors for which this tightening strategy is interesting?
Michael Laue: Generally, this approach is interesting for manufacturing industry as a whole. In the past, we have worked together with companies in the fields of electrical and electronic systems, optical systems, precision mechanics, communication systems, medical devices, the automotive industry, the aerospace industry and wood processing.
To date, seating control has mainly been used in the low torque range. Enquiries very often concern tightening operations with torque values from 1.2 Newton-centimeters (Ncm, - that is just 0.012 Newton-meters) to 2.5 Newton-meters (Nm). – This low torque range is fully covered by our Micro Torque tightening system. However, higher torque values can also be covered without any problems as Power Focus 6000 and Power MACS controllers now allow seating control strategies with considerably more powerful tools.
Atlas Copco customers with higher torque requirements have also started to recognize the benefits of a seating control strategy. Recently, we carried out analyses with tightening torque values up to 1,000 Nm, with the seating point reached at about 200 Nm.
The third part of our three-part Expert Hub series on the seating control tightening strategy, which you will find here, presents a practical example.
Download our flyer "Joint analysis with seating point detection":