When clamping and toolholding specialist Röhm needed to upgrade its grinding processes it returned to Kellenberger for a solution and its latest machine technology and automation options. PES reports.
Röhm can look back on a history of more than 100 years as a manufacturer of tool and workpiece clamping systems. During these years the company has grown steadily and today serves international markets with three production facilities in Germany and 1,300 employees worldwide.
At the main German plant in Sontheim, 750 employees primarily manufacture technology solutions for sectors such as the automotive industry, mechanical engineering, aerospace and many others in 41,000m² of factory space. The parts in question are finished on Kellenberger premium grinding machines.
After several difficult years, the acquisition of Röhm by Austrian investor Helmut Rothenberger Group in September 2017 brought more stability to the company with Gerhard Glanz taking over both as CEO and co-partner at Röhm. In his view, the company’s portfolio fitted perfectly with the existing business areas of the Rothenberger Group, which generates a sales volume of €1.3 billion from 100 operating companies, many of them in the machine tool sector.
Applying an extensive restructuring plan, Mr Glanz achieved a turnaround in fortunes within a few months at Röhm. He restored confidence both among employees and customers and brought it back into profit. In order to make the company fit for the future, an investment sum of several million euros was also made available which involved new machinery and systems. The aim was to produce Röhm‘s high-tech products in even better quality but at the same time more cost-effectively.
Made in Germany with Swiss advances
For division manager Alexander Scheitenberger and his 35 staff members the investment came at the right time. Mr Scheitenberger’s department manufactures tool clamping systems, 40% of which are customised special designs.
A trained industrial mechanic, Mr Scheitenberger has been with Röhm since 1990 and is very familiar with all the machining processes required in Röhm portfolio, which includes drill chucks, centre punches, lathe chucks and vices, robot gripping technology, power chucks, clamping cylinders, mandrels, and tool clamping systems.
The parts were being machined on a Kellenberger Kel-Varia universal grinding machine with a centre width of 1,000mm, which had been in use for 18 years. However, parts for key components were no longer available, making a replacement investment unavoidable. Mr Scheitenberger and head of production Erhard Bader agreed that the new machine should once again be a Kellenberger.
He says: “We had very good experience with the Kel-Varia. The reliability, accuracy and process safety of the machine over its runtime was outstanding. In addition, the cooperation with Kellenberger has always been characterised by a high level of professionalism. Erich Ziegler, the area manager who is responsible for us gave us excellent advice on the new procurement.”
Since 2018, the Kellenberger product portfolio has offered two machine designs, able to meet the machining tasks at Röhm. The Kellenberger 100 platform concept proved to be the best solution, especially since Swiss manufacturer Wenger had specially adapted an automation system for the machine.
Drawing board versatility
The task assigned to the engineers in St. Gallen, Switzerland in regard to the design of the Kellenberger 100 was to develop a platform on which different machine concepts could be realised with a strong element of customer specification.
The idea of a high-performance, low-cost grinding machine within the group was integrated into the design so a modular solution on a common platform was instigated. This also enabled a new assembly system on the shopfloor to reduce throughput time, enable cost-efficient production of the machine, and therefore introduce a good price/performance ratio.
The machine design was also optimised in close cooperation with the service department, resulting in faster maintenance and servicing and better accessibility to wear-intensive components.
The Kellenberger 100 offers a wide range of standard configurations for a great variety of grinding operations. The machine is available in centre widths 1,000/600mm and a centre height of 200mm and is designed for part weights of up to 150kg. A higher drive power for the grinding wheel (11.5kW) ensures increased productivity, while the newly designed guide in the Z-axis brings greater profile accuracy. For higher accuracy in non-circular grinding, the C-axis is equipped with a direct drive. Röhm opted for a machine with a centre width of 1,000mm.
The K100 has a compact, collision-free tandem grinding head with motor spindles. Ten grinding head variants are available for optimised design of the machine in relation to the machined parts and the reinforced casing allows the largest grinding wheel diameters for internal grinding (up to 125mm).
The user-friendly, ergonomic design of the Kellenberger 100 machine is complemented by an intuitive operator interface via a touchscreen and the machine is equipped with a state-of-the-art FANUC 31i CNC control. Various ready-made software packages are included as standard or can be added as an option. They cover simple and complex workpieces in the shortest machining time, and complex contours and profiles.
Smart loading solution
The Kellenberger 100 is ideal for a wide variety of automation solutions. Swiss automation specialist Wenger has custom-designed its loading system WeFlex for chucks and shaft parts especially for the K100. The WeFlex loader enables automated processing of shaft parts 6 - 100mm diameter.
Interchangeable gripper heads facilitate quick changeover between shaft and chuck parts and in the stacking module, eight pallets of 400 x 600mm size are available. Inserts for shaft or chuck parts can be inserted in the pallet frames.
The machine is loaded via telescopic line gantry. An automatic hatch closes off the machining space during machining to ensure the thermal stability of the machine. Directly at the infeed, electricity and compressed air use is recorded, which allows the energy consumption of the WeFlex to be noted and visualised.
To reduce energy consumption, the speed of the WeFlex is automatically adjusted to the cycle time of the processing machine. An image-guided setup wizard assists the operator when changing over to a new workpiece.
Wenger managing director Michael Wenger supervised the initial commissioning, which was followed by a training for the Röhm employees at Kellenberger. One week after machine commissioning, three-shift operation was resumed.
“The reliability of the loader is very high,” notes Mr Scheitenberger. “We haven’t had any downtime so far.”
Exceeded expectations
The service package also includes remote maintenance of the machine and minor service work is handled internally at Röhm.
“A couple of our employees have undergone service training at Kellenberger with a focus on the new machine, so they can carry out minor repairs themselves,” says Mr Scheitenberger. “There is no need to call the Kellenberger service team for a minor issue but if you do need them the service is fast and reliable.
He adds: “In terms of accuracy the new machine has brought us a quantum leap. Today, we grind with an accuracy of 2µm with process reliability. The surface quality of the machined tool clamp is so good that, with the same polishing times, the results are many times better, from Ra 0.3-0.4µm to below Ra 0.1.”
“Also due to the larger grinding wheel and because the new machine is simply faster than the old one, we have 25% increase in productivity. In addition, staff costs are 30% lower, because due to automation one operator is sufficient for two machines. It doesn’t get any better than that!”
Kellenberger grinding machines are available from DF Precision Machinery in Lutterworth, the sole UK agent for all Hardinge grinding brands.
DF Precision
https://dfpmach.com
Kellenberger
www.kellenberger.com
