The test tube must go into the centrifuge, the component at its correct position, and the package onto the conveyor belt: gripping objects and placing them someplace else is a fundamental mechanical action in most work processes. In modern systems, “pick-and-place” is performed by automated grippers. They must operate both powerfully and delicately millions of times over. Increasingly, the necessary power comes from electric motors, such as the BX4 from FAULHABER. The Zimmer Group uses it for its GEP2000 gripper series, which can often be found in laboratory automation.
Testing and vaccination have proven to be effective against coronavirus. They have provided a way out of lockdown and a return to normality. But the pandemic also revealed the limits of what is possible here. With the exponential spread of the virus, demand exploded — first for PCR laboratory tests, then for rapid tests, and later for vaccines. Capacity was inadequate every step of the way. For many, the wait for test kits and vaccines seemed endless.
Laboratory automation against Covid-19
The pharmaceutical industry, medical technology, and medical laboratories did work quickly. This also applies to the expansion of production and the increase of testing capabilities. A key factor in this success was automation. In laboratories, the pandemic proved to be a significant driver of automation. Automatic laboratory devices and universal, flexible robots can relieve specialists of a great deal of work and increase both throughput and efficiency.
The automatic gripping and handling of samples, pipettes, or reagents are among the central, constantly recurring process steps here. For this purpose, delicate, industrial small-parts grippers are required. Two different technologies are generally available for gripping, explained product manager Maik Decker, who is responsible for this area at the southwest German manufacturer Zimmer Group. “Up until now, most grippers in industry have been powered pneumatically — with compressed air. This technology is, however, not suitable for the hygienic environments required in laboratories, in medicine, and the pharmaceutical and medical technology industries. Grippers with electric drive are therefore used in these areas.”
Electric motor makes grippers flexible
These grippers also have another advantage — they function without a compressed air system and the associated lines. In some industrial sectors, these are standard equipment in production facilities — electricity is, after all, available everywhere. Besides, the machines in which the grippers are installed operate with electric power. An electrical connection is much easier to install than a compressed air supply. The control of electric components is both simpler and more flexible than working with pneumatics. “We see a clear trend toward the electric drive, not least in the automotive industry,” said Decker.
New products from the Zimmer Group, such as the new GEP2000 series, serve and consolidate this trend. The small parts gripper can — depending on the version — grip and hold components weighing up to five kilograms but can likewise handle delicate and sensitive parts such as a test tube without a problem. “The advantages of the electric drive also include the ability to adapt the gripping force to various objects at any time,” said Volker Kimmig, team leader for software at the Zimmer Group. “With the appropriate controller, the gripper can switch between different parts during a running process.”
10 million cycles without maintenance
The power for these work steps is supplied by a brushless DC-servomotor of the BX4 series from FAULHABER. In addition to high torque, the strengths of the four-pole drive include its low vibration and low noise, compact design, and a long service life.
“We guarantee this product will perform over 10 million cycles without maintenance,” said Kimmig.
The development engineer uses the production of car keys as an example. “Large quantities and high throughput set the tone here. The gripper robots work under very high-paced, permanent stress and short cycle times. The motor must therefore start and then stop again at very short intervals. Decisive here is the motor’s acceleration, as every tenth-of-a-second counts in the process. Moreover, the motor needs to efficiently dissipate the heat that forms in such an operation to eliminate the possibility of overheating.”
Mechanical self-locking
The gripper series has one unique feature in common with other Zimmer Group products: The motor power is transferred to the jaws by a worm gear drive with a steep pitch. Even in the event of a power failure, the gripping force is retained, and the respective position is held. Once gripped, a workpiece is held securely by this mechanical self-locking function, without an additional device such as a brake being required.
The drive electronics in the two gripper types operate slightly differently. With the GEH6000, the encoder signals of the drive are used for positioning the jaws. With the GEP2000, this task is performed with the help of a positioning sensor. Both solutions achieve a high degree of repeatability. The specified path of the jaws is reproduced to within one five-hundredths.
“In many applications, the prepositioning when lowering the gripper to the target object is very important,” said Kimmig. “In constrained spaces, the open position is often only allowed to be very slightly larger than the closed position. When “maneuvering” a robot arm in a complex environment, it may also be necessary to make very precise presettings. We do this using very precise electromechanics, where the motor again plays a crucial role, as well as with a flexible data connection.”
Faulhaber
www.faulhaber.com
Filed Under: Motors • servo