Mar 05, 2020 — A high degree of automation – supported by elements of Industrie 4.0: component machining processes at KUKA provide insight into future-oriented production processes.
At first glance, production hall 10 at KUKA’s site in Augsburg looks just like any other production environment at a German or international machine manufacturer: a slight smell of oil is in the air, machine tools from various manufacturers are hard at work machining metal parts – and diligent employees are running the show. One of these employees is Rainer Eder-Spendier, Administrator for Automation and Robotics in Hall 10. “I am passionate about this hall,” says the 51-year-old. “The high and sensible degree of automation in production is what sets us apart. We embrace intelligent automation and digitization here.”
What you don’t notice at first sight: all of the machines in the hall are connected to the cloud and feature various Industrie 4.0 functions. Standing with a tablet in hand, in front of a Burkhardt + Weber safety fence that surrounds a machine tool, Rainer Eder-Spendier explains: “For instance, we have a digital overview of the entire hall. This is similar to the map apps for smartphones. It allows me to monitor all of the machines and retrieve their data.” With a quick tap of his index finger, he checks the status of two Heller machining centers which are loaded and unloaded by a KUKA robot on a regular basis. Similar to a smart watch or a fitness tracker, the robots and machines collect a wide array of data and transmit these data to the cloud. The data are then displayed in various visualizations on the user interface of the tablet. “But that’s not all,” says the Munich native, who has been working for KUKA for more than a quarter of a century. “If error messages appear, we can make use of a wiki-type service that has been compiled by our service technicians over a number of years. The database comprises almost half a million proposals for solutions. We can also retrace every process step in retrospect using the built-in technology – this works in a similar way to a black box on an airplane. What’s more, we can have the software notify us of any irregularities in the production process – this is similar to an ECG.”
Communication as the basis for smart production
There is a total of seven cells and eleven robots in Hall 10. The robots, which are from a number of different model series, were all manufactured by KUKA. The machines that they work on are commercially available machine tools from various manufacturers. The robots machine components such as base frames, rotating columns, arms and link arms. The components are assembled right next door in the robot assembly shop. “In this hall, the robots work on the various components that we need to manufacture our robots,” says Rainer Eder-Spendier, in summary. He then goes on to emphasize: “Not only was it important to test the new technical possibilities exhaustively, but also to deploy them in a truly sensible manner. It is also important that the machines have interfaces that accommodate what is referred to as the handshake.”
The handshake refers to the communication between the robot and the machine tool. This is essential if the components of the system are to coordinate with one another. In the cell, the robot can act either as a master or a slave. As a master, the robot specifies the procedures and notifies the machine that, for instance, a workpiece has been loaded and the door can now be closed. If the robot is deployed as a slave, it responds to commands from an external controller.
Shorter throughput times, greater efficiency
Machine tools are usually loaded manually by workers. The worker often stands around waiting for the machines to finish machining the workpiece. Once the machining proce-dure has been completed, the worker removes the workpiece and sets it down on a pallet before loading a new workpiece into the machine. Not only is this procedure monotonous, it is also relatively inefficient. As we can see from Hall 10, the process can be optimized using automation. “In our hall, the robots take on the tasks of loading and unloading the machines,” explains Rainer Eder-Spendier. “Consequently, very few human workers are involved in the production process. In fact, it is possible to run the production process without human involvement for a certain period of time, even on weekends and during night shifts.” To make this possible, the cells are equipped with feed units such as turntables and feed conveyors. The workers load these manually with the components that are to be machined. The robot therefore has access to a stockpile that will last up to eight hours depending on the number of prepared workpieces and tasks to be performed by the machine.
The level of productivity is also improved by the fact that the robots also carry out secondary tasks. “In some of our cells, the robot cuts helicoil threads into pre-drilled holes while the machine tool machines the next workpiece,” says Rainer Eder-Spendier, citing an example. In most of the cells, workpiece deburring is another task that the robots perform. In this way, waiting periods are used efficiently, and the throughput times of individual parts are shortened because the machines are relieved of machining tasks such as drilling holes and milling operations falling within a tolerance range of +/- 0.2 mm. Thus, better use can be made of valuable machining time on the machine tools and more parts can be produced.
Robots work hand in hand with machine tools from various manufacturers
In practice, one of the robot cells in Hall 10 could look like this: three machine tools from the manufacturer Grob have more than 30 of the system’s pallets at their disposal and can therefore respond quickly and flexibly to various requirements. The worker clamps the workpiece to be machined in a clamping fixture at a changeover station. Next, the component is loaded into the cell together with the pallet and the fixture. A KR 600 R2830 FORTEC robot performs the chain of individual steps and the material transport from the machine tool to the reworking cell where the machined metal parts are finished – for example, deburred, drilled or furnished with helicoils. The robot approaches the three machines via a linear unit and then brings the finished part back to the relevant operator position. The worker releases the clamping fixture, removes the part and sets it down on a pallet.
In another cell featuring two machining centers from the manufacturer Heller, the procedure is similar. With the aid of a pneumatic gripper, a KR 500 L480-3 MT FORTEC robot picks up a workpiece that has been placed onto a turntable and loads it into one of the two machines. To enable it to load both machines alternately, the robot is installed on a linear unit. Four feeding stations provide sufficient raw material. As soon as the machining process has been completed in the machine, the robot deburrs the part at the changeover station. Finally, the robot sets the part down on a turntable.
A machine tool from the company Burkhardt + Weber is also loaded and unloaded by a KR 500 FORTEC robot. The machine tool, which machines link arms and rotating columns, is equipped with a double pallet changer: one pallet holds the clamping fixtures for the link arms, the other pallet holds the fixtures for the rotating columns. While the robot loads a workpiece onto one pallet, the machine works on the workpiece that is clamped on the other pallet.
The advantages of automation and networking
“Automation makes the worker’s tasks significantly easier because, in most cases, the worker is no longer required to manually load the machine tools with heavy workpieces,” says Rainer Eder-Spendier. The worker is merely required to supply the material. This, however, takes a lot less time and physical effort, meaning that the system can achieve a greater level of productivity. Another advantage: it is not necessary to have profound robot-specific expertise to carry out the deburring tasks.
As soon as the cells have been switched to this mode, they can be operated in G-Code using the KUKA.CNC software like a conventional machine tool. The data that are recorded – even those that pertain to components manufactured by companies other than KUKA – are made available in the cloud. That way it is possible to have full visibility and exercise full control over the current production process, achieve a greater level of transparency and optimize task scheduling at all times.