22. March 2021

Test-Fuchs optimizes aerospace test stands

Linz, Groß-Siegharts - A turnover of over 60 million euros, 600 employees, an export quota of over 90%, prestige customers such as Airbus, BOEING or Lufthansa: Test-Fuchs GmbH from Groß-Siegharts (Lower Austria ) has been an indispensable partner of the international aerospace industry for over 70 years. The family company's test systems check the operational capability of a wide variety of aircraft components such as hydraulic pumps, cylinders for rudders and tail units or hydraulic motors. In the future, a robot arm with a highly specialized screwing unit will be used for a very challenging test bench project, where settings must also be made on the test item during the up to 30 test cycles. For the operator, who previously had to make the settings manually, this not only saves time but also means a significantly higher level of comfort and safety. The highly specialized screwing unit was developed in just two months by the systems engineering experts at the Linz Center of Mechatronics GmbH (LCM). It recognizes a wide variety of screw heads, carries out the necessary tool changes, fixes the test settings, logs the results - and all of this completely automatically. The reactions from customers have so far been extremely positive. The first test stand with a robot arm will be delivered in February 2021.

To test a hydraulic pump, the flow restriction must be changed up to 30 times. Each pump is operated over the entire speed range, which gradually creates a family of characteristics. The maximum output of the pump must be set using an adjusting screw. Up until now, the tester had to adjust the screw manually and run the test cycle. "That is why we wanted to offer our customers the option of automating this central aspect of pump testing," emphasizes Testfuchs owner Volker Fuchs, who is now the third generation to run the family business. "When looking for a suitable development partner for this, we quickly chose LCM because we had already worked together successfully on other projects."

Pit stop in small format

The Linz mechatronics experts have developed a highly specialized screwing unit for a standard Kuka robotic arm. “The demands on speed and precision could best be compared with a pit stop in Formula 1,” recalls Bernd Winkler, who heads the Systems Engineering department for overall mechatronic systems at LCM. “In contrast to Formula 1, however, the screws on the hydraulic pumps to be tested are sometimes very hidden. So we had to keep the system as small as possible, which made the task even more difficult. ”The problem was solved with a space-saving 3D CAD design. For this purpose, two high-precision harmonic drives with high torque were installed - one for the adjusting screw, the other for the lock nut. A high-precision force and torque sensor is mounted between the two units, which precisely sets and automatically records the tightening torque specified in the standard. In addition, the system recognizes a wide variety of screws such as head-slotted, head-Phillips, external hexagon, internal hexagon or internal square and carries out any necessary tool changes automatically. The screwing unit detects the exact location of each screw, puts it down gently, loosens the screws, and fixes them in the new position.

Speed ​​miracle with high potential

Thanks to the new robot arm, the setting processes are much faster and more reproducible than previously possible. In addition, an examiner can no longer operate just one, but, in this case, up to five test stands at the same time without having to leave his workplace. Because the test environment is naturally oily, hot and, at up to 95 decibels, extremely loud, there is also a noticeable improvement in occupational safety. “With our expanded system, around 800 test runs can be carried out per year,” emphasizes Volker Fuchs. “But we were not only able to noticeably increase the number of test results, but also the reliability of individual test results through the automation of processes and meticulous logging together with LCM. A continuation of the partnership is therefore quite likely and we are extremely optimistic that our new test stands will meet with broad interest from our customers has been received by Test-Fuchs.