Small and medium-sized enterprises form the backbone of the German economy. Many small and medium-sized companies are global market leaders with strong traditions. One of these “hidden champions” is the machinery manufacturer MERZ based in the south-west German town of Hechingen. Founded in 1900, the company has come to specialize in the production of single-jersey circular knitting machines with small nominal diameters. The company is a global leader in the construction of circular knitting machines used in the production of medical stockings and compression garments.
In order to remain competitive in the long term, MERZ made the decision to automate four machining centers in their production department. The goal was to improve quality, flexibility and productivity, minimize downtime and shorten delivery times. The company has managed to achieve this with a KUKA robot of type KR 500 R2830 F (Foundry) from the KR FORTEC series. Since 2015, it has linked four loading centers, filled and emptied changeover stations and ensured optimum utilization of the machine tools.
Even small production batches can be manufactured automatically in three-shift operation
The machinery manufacturer MERZ commissioned the integrators SOFLEX Fertigungssteuerungs-GmbH and wbt automation GmbH & Co. KG to convert the production process to an automated solution. Founded in 1984, the company SOFLEX from Rottenburg specializes in the implementation of control systems for flexible production systems with medium-sized quantities down to a batch size of 1 and significant component diversity.
Customers in the machinery construction, energy technology, plastics, optical goods and automotive and aircraft construction industries benefit from the experience and expertise of SOFLEX. wbt automation GmbH & Co. KG was founded in 2014 in Spaichingen and supports customers in the machinery and tool manufacturing, surgery and medical technology, automotive and automotive supplier industries from manufacturing to production and assembly right through to testing technology.
Automating the four DMG machining centers – machine tools from the manufacturer DMG MORI – had the objective of ensuring that the system can operate 24 hours a day, 7 days a week despite the small batch sizes. Furthermore, the automated system had to be integrated into MERZ’s IT landscape in a user-friendly manner and stipulations regarding ergonomics at the changeover stations had to be met. SOFLEX and wbt automation opted for a robot-based solution.
Based on these requirements, KUKA had the ideal robot in its portfolio: the KR 500 R2830 F from the KR FORTEC series for handling heavy payloads. In this application, it is combined with a KUKA linear unit in order to maximize the workspace available.
One of SOFLEX’s reference projects formed the basis for the automation project at MERZ: a production system that presents machine pallets and stored raw materials for further processing. The KR 500 R2830 F is at the core of this system. It moves on a KL 1500-3 linear unit with a length of 18 meters to tend the four manufacturing systems located adjacent to one another. The robot has the job of loading and unloading the changeover stations at which the machine pallets are equipped with the corresponding workpieces / raw materials.
In doing so, it plays a decisive role in the production process and is the linchpin between the machining centers. It performs the automatic transfer of machine pallets and raw material pallets between the changeover stations, storage areas and machine tools. This enables the four machining centers to work fully automatically around the clock. The SOFLEX control system was additionally integrated into the company IT network.
“MERZ wanted the automated system to be integrated into its internal flow of information in order to ensure that the NC and tool data could be provided to the machines automatically. This is a key factor in preventing unnecessary downtimes and achieving maximum productivity,” emphasizes Franz Klaiber, Managing Director of SOFLEX.
A robust courier between the machining centers
Featuring a payload capacity of up to 500 kg, the KUKA KR 500 R2830 F from the KR FORTEC heavy-duty series has a reach of over 2.8 meters, thus covering an exceptionally large working envelope with very long reference load center distances. The compact design without disruptive contours and the more streamlined appearance make the robots of the KR FORTEC series suitable for use in cramped cells as well as in completely new cell concepts.
Goals achieved, success quickly evident
Strong cooperation between the two integrators was decisive in ensuring that the system could be completed quickly and successfully. “From the start, we worked closely with SOFLEX to specify mutual interfaces and individual areas of work. We also tested the software and the robot system thoroughly prior to commissioning,” adds Burkert. The MERZ employees were able to operate the robot with confidence after only a brief period of training. They are now able to issue all of the necessary commands and tasks by way of a touch panel without any particular knowledge of robotics.
