Automated derinding of cheese
At an organic cheese dairy in the Austrian Tyrol, a Stäubli six-axis robot is busy de-rinding and coating irregularly shaped blocks of cheese, a demanding job that calls for maximum resilience. The TX2-90 HE is able to withstand intensive cleaning with aggressive detergents delivered by a high-pressure lance – a treatment that would soon spell the end for the average standard robot.
At any one time, up to 650 tons of organic cheese made with milk from the finest Tyrolean hay-fed cows are maturing in the 160-meter-long, 10-meter-high man-made cave of the Plangger cheese dairy in Niederndorf (Tyrol). Since early March 2020, a series of otherwise strenuous tasks have been carried out in a fully automated robot cell. A ceiling-mounted Stäubli TX2-90 HE (humid environment) handle the entire derinding of cheeses as well as the coating of Sennkäse cheeses.
In the past, the hard rind was removed manually with a scraping iron. This took about 10 minutes per 600-millimeter block and required immense physical effort on the part of the employee. Today, the robot does the job more accurately and economically than ever before.
Fast and precise derinding performed by a robot
The Stäubli six-axis robot shaves the rind off the unevenly shaped cheese rounds with high accuracy thanks to 3D path tracking. Further, with a cycle time of around two minutes per cheese, the TX2-90 HE is approximately five times faster than a human doing the same job. Coating the smaller Sennkäse cheeses is even faster, with a cycle time of 20 seconds, which is equivalent to 600 kilograms per hour.
The first step of the process involves paring the top and perimeter. The cheese is automatically lifted from the belt by a vacuum suction gripper and placed on a rotary table. The robot does not begin its work until the cheese has been measured by laser, since the blocks are irregular in shape and no two are ever identical. The paring tool can then begin to remove the rind, with the Stäubli control system adjusting the distance between the blade and the surface in real time.
When the time comes for the underside to be derinded, the handling unit grips the cheese at the center, swivels it around, and places it on a second rotary table. Here it is measured by laser again before the final stage of derinding proceeds. When this a completed, the block is lifted and placed on the discharge conveyor belt.
Top-level output, quality and hygiene
The already stringent specifications that apply in the food sector are taken to an even higher level in cheese manufacture, due to the deliberate use of bacteria. Cleaning of the Plangger plant is therefore carried out with fat-dissolving, alkaline and milk stone-dissolving acidic agents as well as with water at 55°C. The robot cell is robust enough to withstand cleaning procedures with a high-pressure lance which are necessary several times a week.
The Stäubli six-axis HE robots are conform to HACCP and have a unique hygiene concept. There is no other truly viable alternative to using these robots in combination with H1 oil, which is the only kind approved for direct food contact. They have a particularly resistant surface as well as the option for pressurized housing. Just a small amount of overpressure is enough to effectively prevent the penetration of water and cleaning agents. Washing and rinsing with running water presents absolutely no problem for these robots.
Compared to manual processing, the cheese dairy achieves a much more even derinding with the robot, which has the additional benefit of less waste. The precision of the three-dimensional path tracking during the paring process is crucial, with the distance-measuring laser function on the robot arm and the rigidity of the six-axis machine playing especially important roles.