Gebrder Gienanth-Eisenberg GmbH, a German foundry, produces gray iron, ductile iron, and compacted graphite iron castings, including crankcases for high-performance six- and eight-cylinder engines. In preparation for producing these crankcases, Gienath manufactures approximately 400 sand cores every day.
Because the foundry promotes a strategy of ongoing continuous improvement, its operators sought to increase production rates and product quality, and to reduce labor costs, during coating and handling of the cores. After an extensive evaluation, Gienanth identified two core-handling operations for their initial automation efforts. Historically, these were manual operations. In the conversion to automation, the operators’ greatest concern was to ensure that robotic handling would not stress, crack, or otherwise damage the relatively delicate sand cores.
For these critical processes, Gienanth settled on two KR 500 heavy-duty robots supplied by KUKA Robotics. But, before placing the contract Gienanth commissioned a feasibility study to investigate possible methods for picking up the cores, and how the cores would respond to the robot motions. The study evaluated various motion patterns, speeds, and accelerations/decelerations, for impact on the sand cores. After a successful pilot run, the robots were deployed.
The cores weigh up to 260 kg and measure up to 1,135 mm high. They are moved on a conveyor from the furnace to the rough orientation pick-up station for the first robot. A photoelectric sensor signals to the KR 500 when a sand core is present. Then, the robot registers the location of the core with a laser, determining its exact position in the pick-up station.
Using its universal clamping gripper, the robot picks up the core and dips it to a pre-set depth in a water wash to protect the sand from the molten metal, preventing burn-in on the product. By manually changing the gripper jaws on this robot, the end-effector can be converted handle four different families of sand cores.
After dipping the core into the bath, the KR 500 lifts it out again and transfers it to the apron conveyor of the drying furnace. During this process the robot carries out rotational motions to allow the wash residues to drip off, to prevent “runs.” Some cores require the wash to be applied only on specific surfaces. For this, the robot applies the wash using a flood lance.
Once on the conveyor, the sand cores pass through the 170°C drying oven and a cooling zone. From there they are picked up by the second KR 500, which has three different tools, and palletized for transfer within the plant. For the most common cores, Gienanth uses an inflatable Liftboy gripper, which is lowered into an opening in the top of the individual core and expanded using compressed air.
First, though, this robot uses a laser beam to locate precisely the opening in the core, for pick-up. Other cores are provided with a lifting ‘I’ hook that makes it possible for the robot to pick them up using an additional gripper. The third end-effector is a plate gripper that clamps the cores between its jaws.
KUKA six-axis foundry robots are designed for high-duty cycle applications, and allow customers to automate their operations with confidence in long service life and minimized maintenance costs thanks to a design that resists heat and contamination. Gienanth has fully implemented these automated systems, and realized the labor cost savings, shorter cycle times, and improvements in process and product quality.