There is an increasing rate in the use of automation in materials testing, especially since even the smallest disruptions can alter measured values. Time consuming and monotonous tasks are also often carried out by robots. ZwickRoell offers a wide range of possibilities for automation in materials testing. Testing systems range from efficient automation of small series tests using collaborating robots in the lab to fully automated testing laboratories that work around the clock.
Classic robotic testing systems, for example based on industry robots, have been used successfully for years. Because of their high load capacity they are able to move even heavy specimens. The wide range of specimen magazines makes them ideal for long test series – hundreds, and even thousands of specimens are autonomously processed magazine by magazine. In example, through the use of different roboTest testing systems from ZwickRoell. In connection with the corresponding testing machine, they are not only the perfect solution for standard tensile tests on metals or plastics under normal conditions, but flexure tests, temperature controlled tensile, notch impact and puncture tests, as well as measurements of ball indentation hardness can also be automated.
Not only can the actual test be performed without employee intervention, but ZwickRoell also builds fully autonomous testing laboratories using AGVs (automated guided vehicles) and additional handling robots that are coordinated with ZwickRoell’s autoEdition 3, just like the robots used for the testing process. When necessary, they run 24 hours a day and autonomously assume materials testing, from placement of the specimens onto a transport belt to the disposal of the destroyed specimen. All that's left for workers to do are specimen production and preparation. A fully automated testing lab is especially worthwhile for quality assurance in ongoing production with high material throughput. After removing the specimens or materials from the manufacturing process, they are formed into the required shape and size. Every specimen is given a bar code or 2D code and can the be automatically and clearly identified in the system. The only thing left is transfer of the specimens to the robot testing lab: the specimens are placed on a belt conveyor and sent risk-free within reach of the robot, they are recognized by their code, assigned to the correct test and testing machine, and sorted onto the proper tray.
Further transport is carried out by AGVs, which take the trays to the corresponding testing machine. With an integrated laser navigation system they create a map of their surroundings and independently determine the ideal route to their destination. With the autonomous navigation, they are superior to the classic solutions that, for example, have to follow a wire embedded in their path or an adhered contrast line. Their only option to react to obstacles is to stop and wait until their path is clear or by communicating with an operator. If the path is not cleared, the delivery is stopped, and worst case until there is no material left at the target destination, and an employee has to go search for it. The solution from ZwickRoell has the ability to drive around obstacles, ensuring an uninterrupted chain of transport. Once having arrived at the intended testing machine, the AGV loads the tray with the new specimens into the testing system’s magazine. One of the recognized robotic testing systems from ZwickRoell, for example the roboTest L, assumes processing of the delivered specimens: equipping the testing machine, the testing process and the transfer of data to the customer’s software systems and, of course, the removal of the destroyed specimen are fully automated. The identification numbers of the specimens are read by the cameras so that the test data can be correctly linked with the corresponding specimen. An AGV takes the empty trays and transports them back to specimen preparation. There they are refilled and the cycle starts over.
Automating small series
The work carried out successfully at a large scale saving a lot of time, up until now has not been economical at a small scale. The installation of stationary robotic testing systems is costly and requires time, as well as specialists who are familiar with their programming. In addition, depending on the system, a wide range of safety measures are necessary to avoid injuries and accidents: the powerful industry robots are not intended for use in direct collaboration with humans. They do not have the option to react to their environment such as through an emergency shut-off, if a person is within their working range. In most cases a safety barrier is required, which eliminates the direct interaction of man and robot. Therefore, up until now small series tests have been carried out by humans. Even if a task is extremely monotonous, it was much quicker to entrust an employee with 20 tensile tests or 50 Charpy impact tests, than to install a large robotic testing system. For the first time, with roboTest N, ZwickRoell is able to provide the possibility to automate series testing with a small number of specimens with a lower specimen weight. Based on a smart robot, the system is fully integrated in ZwickRoell’s autoEdition 3 and testXpert III. Therefore, a robot operator terminal or special robot programming and operating knowledge are not necessary. Instead the roboTest N, in the truest sense of the word, is taken “by the hand” and taught the necessary point of reference. In regards to software, parameters are set in a familiar software environment. Not only is the setup of the smart robot easy and uncomplicated, its work speed and force are similar to human proportions. Sensors detect external influences and stop the system if something gets in its way. Therefore, once cleared with laboratory safety personnel, the roboTest N can work alongside persons without the need for additional safety measures – locked off work areas are unnecessary.
Diverse application options
The light weight robot is fastened to a movable table specifically intended for the robot. With this mobile base, application options are widely expanded. The smart robot can be moved to the appropriate testing machine and connected to the system. This not only allows for uncomplicated processing of alternating small series, but also automated performance of a variety of tests. Tensile and compression tests can be as autonomously processed as three-point-flexure tests, Charpy impact tests or hardness tests. The movable base also provides space for custom manufactured magazines – for example in a 3D printer – from which the roboTest N can automatically take additional specimens. If started just before the end of a shift, the robot extends the workday by the contents in a magazine, and the results are available at the start of the next day. Automation of monotonous standard tests allows qualified employees to focus on more complex test applications that require more attention. The independence from the operator that is achieved with the use of a robot is also a benefit. The uniform movement sequences in feeding the testing machine and with that, consistent positioning of the specimens, eliminate user errors or inaccuracies and increase the reliability of test results.
Robotic testing systems provide the user with a number of benefits in series testing, from time savings all the way to improvement of the informative value of the test results. With various roboTest testing systems ZwickRoell covers the full range of testing automation – from short-term support for continually changing small series in the lab, all the way to fully automated testing laboratories without human intervention.