Test tubes must be placed in a centrifuge, components placed in correct positions, and packages placed on a conveyor belt. Grabbing an object and placing it somewhere else is a fundamental mechanical motion in most work processes. In modern systems pick and place is performed by automatic grippers. It has to work powerfully and delicately millions of times. An increasing need for power comes from electric motors such as the BX4. foul harborThe Zimmer Group uses this for their GEP2000 gripper series, commonly found in laboratory automation.

Testing and vaccination have proven effective against coronavirus, offering a way out of the lockdown. But the pandemic has also revealed the limits of what is possible. Demand exploded as the virus spread exponentially. First PCR lab tests, then rapid tests, and later vaccines. Capacity was inadequate at every step, and for many the wait for test kits and vaccines seemed endless.

Inspection automation against Covid-19
The pharmaceutical industry, medical technology and medical laboratories worked quickly. This also applies to expanding production and increasing testing capabilities. A key factor in this success is automation. In the lab, the pandemic has proven to be a major driver of automation. Automated laboratory equipment and universal, flexible robots can reduce the work of experts and increase throughput and efficiency. Automated gripping and handling of samples, pipettes or reagents is one of the central and ever-repeating process steps here. For this purpose you need a delicate industrial small part gripper. Maik Decker, his product manager in the field at southwestern German manufacturer Zimmer Group, explains that in general he has two technologies available for grips. “To date, most grippers in the industry have been pneumatic, i.e. driven by compressed air. However, this technology is not suitable for the hygienic environment required in laboratories, medicine, pharmaceuticals and medical technology. Therefore, electrically driven grippers are used in these areas.”

Electric motor makes the gripper flexible
Besides hygiene, these grippers have another advantage. Works without compressed air systems and associated lines. In some industrial sectors these are standard equipment in production facilities as the machines on which the grippers are fitted run on electricity and electrical connections are much easier to install than compressed air supplies. Controlling electrical components is easier and more flexible than working with pneumatics. “There is a clear trend towards electric drives, especially in the automotive industry,” Decker explains.

Zimmer Group’s new products, such as the GEP2000 series, respond to and enhance this trend. The small part gripper can hold parts weighing up to 5kg and delicate parts such as test tubes. Volker Kimmig, leader of his software team at Zimmer Group, explains: “With the right controller, you can switch the gripper to different parts during the running process.”

10 million cycles without maintenance
Power for these work steps is supplied by FAULHABER’s BX4 series brushless DC servomotors. The strengths of 4-pole drive are high torque, low vibration/noise, compact design, and long life. “This product guarantees him over 10 million cycles without maintenance,” he says Kimmig.

Such motors must also offer additional features to meet the demands of continuous motion in typical pick-and-place applications. The development engineer cites the manufacture of car keys as an example. “High volume production and high throughput set the tone here. Gripper robots operate under very fast-paced permanent stress with short cycle times. The decisive factor here is the acceleration of the motor: “For the whole process, every tenth of a second is critical. We need to be able to efficiently dissipate the heat generated by such operations.”

Proven collaboration

Zimmer Group’s gripper experts knew that FAULHABER’s BX4 meets these requirements. They had previously fitted this series of motors to his GEH6000 gripper family. Basically, this gripper works like the small part gripper. Its stroke, or the distance between the open and closed positions of the gripper jaws, is significantly larger, up to 80mm.

“So the device can cover a wider range of objects of different sizes in the same process,” explains Decker. “On the other hand, the smaller GEP2000 can work even under very limited conditions. Of course, this only works with motors that offer very high power in very tight spaces.”

mechanical self lock
The Gripper series has one special feature in common with other Zimmer Group products. The power of the motor is transmitted to the jaws by a steep pitch worm gear drive. Retains gripping force and retains each position even during power outages. Once gripped, the workpiece is securely held without additional devices such as brakes.

The drive electronics for the two gripper types operate slightly differently. In the GEH6000 the drive’s encoder signal is used for jaw positioning. In GEP2000 this task is performed with the help of a position sensor. Both solutions offer a high degree of reproducibility. Joe’s specified path is reproduced within 1 in 100.

“For many applications, prepositioning the gripper as it is lowered onto the object is very important,” explains Kimmig. “In confined spaces, the open position can often only be slightly larger than the closed position. When manipulating robotic arms in complex environments, very precise pre-settings need to be made. We do this in a very precise way: electric machines with motors again playing an important role and flexible data connections.Our devices include IO-Link and digital I/O You can equip it. This makes it easy to move your device around. Almost anywhere.”