Moller International, a Danish specialist in identifying engineering solutions suitable for the farm equipment sector, exhibited the Bolt-Check system at Agritechnica in November 2019. The system is capable of measuring bolt tension with high accuracy, and using it during assembly could have significant safety and product reliability benefits for farm equipment manufacturers.
Bolt-check is especially suitable for farm equipment since the vibrations resulting from heavy work in the field is similar to that of wind turbines – the sector the system was developed for. Bolt fatigue and loosening through vibrations can be prevented by achieving and maintaining a correct bolt tension in the bolt joint, a process that begins in the factory at the assembly point.
Maintaining the right tension of bolt joints on farm equipment increases safety while minimising the risk of failure and downtime of equipment, which can be especially costly during harvest time. Installation and service costs can also be reduced, a benefit to the machinery manufacturer because product reliability, and thereby company image, is enhanced.
The Bolt-check system was originally developed in Denmark by R&D A/S to ensure more reliable and, above all, safer operation of wind turbines.
“We noticed our engineers were called to fix jobs where the fault was a bolt that had worked its way lose,” tools and structures director at R&D A/S, Søren Schmidt Kellenberger, said. “We started analysing and found out the root cause of the problem was not the bolts themselves, as they were of the highest quality, but it was the wrong clamping force that was the culprit. So, we decided to find a solution, and that is how Bolt-check was developed.
“The correct tension for a particular set of bolt joints is already known to engineers as we can calculate what the optimal tension should be,” Kellenberger added. “What’s difficult, however, is to actually measure if that tension has been achieved. To be exact it’s the friction between the nut and bolt, which is hard to measure. The error tolerance can be as much 30 per cent using standard methods.”
High accuracy achieved through ultrasonic sensors
The Bolt-Check system can measure the right tension to within five per cent accuracy, which is a real improvement to alternative solutions in this price bracket. The Bolt-Check is priced competitively so that it fits volume production when farm equipment makers employ larger bolts of M16 or larger.
Highly accurate ultrasonic sensors and software analysis are used to measure the length of the bolt, which stretches according to how much clamping force is applied. This way of measuring makes the Bolt-Check system a direct measurement method and very precise, whereas using the standard torque method doesn’t render the same accuracy.
Bolt-Check can be used when installing new bolts and when evaluating existing bolts as part of the determining the lifespan of farm equipment. Furthermore, as a part of the process, a unique Bolt-Tag is added to each bolt. The tag gives farm machinery manufacturers full traceability of all bolts. The location of each bolt, as well as service schedule and maintenance, are made easy.
Achieving a consistent clamp force in the bolted joint during assembly is essential for bolted joint integrity. The tool is suitable for most bolt types and requires no special pre-treatment of the bolts.
For more information visit: www.mollerint.dk.
