Having used STUDER grinding machines for its high-precision grinding tasks for many years, Mazak has recently installed an advanced STUDER S41 CNC universal cylindrical grinding machine at the company’s Worcester based European Manufacturing plant.
Established in 1919, Yamazaki Mazak has been contributing to the development of the machine tool industry for more than 100 years. Yamazaki Mazak manufactures advanced machine tools, such as multi-tasking machines, CNC turning centres, vertical and horizontal machining centres, CNC laser cutting machines and flexible manufacturing systems.
In addition to 5 manufacturing plants in Japan, Yamazaki Mazak has manufacturing operations in the United States, the United Kingdom, Singapore, and China. Mazak's Worcester based European Manufacturing plantopened in June 1987 and was immediately recognised as the most advanced machine tool manufacturing plant in Europe.
The impressive European Manufacturing plant is a complete machine tool manufacturing facility. Here Mazak machine components such as spindles, turrets, and tool magazines. As with all Mazak manufacturing plants, the most rigorous Kaizen programmes ensure continuous improvements. Serving all of Europe's markets, more than 80% of the machine tools built in Worcester are exported from the UK into Europe. More than 17,000 Mazak machines have been manufactured here so far and this number continues to grow each day.
As would be expected from a machine tool manufacturer that boasts such a comprehensive range of products, the vast majority of the cutting-edge machine tools and highly-efficient FMS systems used in its European Manufacturing plant are Mazak’s own products. Although, on the rare occasion that the need for a machine tool cannot by satisfied from Mazak’s extensive product portfolio, the required production aid is submitted to a rigorous selection procedure. This was the case prior to the recent installation of the STUDER CNC universal cylindrical grinding machine.
Although the staff of Mazak’s grinding department have enjoyed excellent service from their existing STUDER grinding machines, as it was possible that further progress could have been made by other manufacturers, and in accordance with Mazak’s policy of ensuring best value for money, other grinding machine brands were also considered.
The list of criteria that were considered when comparing the offerings from 5 leading grinding machine manufacturers included, high-precision dimensional and surface finish capabilities, efficiency, flexibility, and thread-grinding abilities. In addition, the levels of customer service provided by each potential vendor were also taken into consideration.
Having carefully evaluated each of the alternative machines, it was found that only theSTUDER S41 CNC universal cylindrical grinding machine met, and in some cases exceeded Mazak’s list of demanding operational criteria. Furthermore, the levels of support previously provided by STUDER and the company’s UK agent, Micronz, aided Mazak’s purchasing decision.
Mazak’s recently installed S41 machine, with distances between centres of 1000mm and a centre height of 225mm, is now delivering on all of the promises made by the staff of Micronz and STUDER. Michal Saletra, New Investment Lead for the UK at Mazak, explained the reasons behind the STUDER S41 purchase. “In accordance with our Kaizen programs, we are continuously seeking improvements throughout our plant. The STUDER S41 machine was installed as part of an ongoing investment program in our busy, temperature controlled grinding department.
“Our new STUDER S41 will be used for the highly precise external grinding of a wide range of company components, including parts that have single figure micron dimensional tolerances, such as our spindles. In addition, many of our components have demanding geometric and surface finish specifications, including parameters such as roundness and roughness. As all of these attributes need to be ground to an extremely high degree of accuracy, we have been very impressed with the highly-precise grinding results, and the speed and ease of operation of our new S41 machine.
“Another major reason for the STUDER S41’s purchase was its ability to very accurately and efficiently grind external threads. Previously we were using a sub-contractor for much of this work. Our new STUDER machine has eliminated our outsourcing in this area and enabled us to bring thread grinding in-house.”
The S41 CNC universal cylindrical grinding machine is available with distances between centres of 1000mm / 1600mm and centre heights of 225mm / 275mm and is able to machine workpieces with a maximum weight of 250kg.
The S41 boasts a range of progressive technical features, including the revolutionary StuderGuide®guideway system, high-precision axis drives with linear motors, and an extremely fast direct B-axis drive. Owing to the availability of a wide range of options, such as in-process gauging, balancing systems, contact detection, and length positioning, the machine can be supplied to correspond with all users’ specific needs.
The S41’s StuderWIN user interface creates a stable programming environment and contributes to the efficient use of the machine. StuderWIN allows the integration of in-process gauging and sensor technology, as well as contact detection and automatic balancing systems, enables the standardised programming of different systems.
Granitan®S103 Mineral Casting is used for the S41’s bed. The excellent dampening behaviour of the machine’s base ensures outstanding workpieces surface finish. In addition, temporary temperature fluctuations are compensated by the favourable thermal behaviour of Granitan®S103.
StuderGuide©guide system, for the longitudinal and cross slides, is moulded directly into the machine base and finished with a wear-resistant Granitan®S200 surfacing material. The precision guideways with high load capacity and dampening properties, provide the highest possible levels of accuracy through the machine’s entire speed range.
Longitudinal and cross slides are manufactured from high-quality grey cast iron and have highly precise, ground guideways. The slides rest completely on the guideways of the machine bed through the entire traversing range, providing the cornerstone for the S41’s excellent straightness specification of of 0.003 mm over 950 mm measured length.
The upper face of the longitudinal slide has a surface that is ground over its entire length and acts as a support for the workhead, the tailstock and all accessories. An additional T-slot with a ground surface enables the optimal utilisation of dressing devices and the slides are powered by linear motors with high-resolution, direct measuring systems. The maximum travel speed for both axes is 20 m/min. This system forms the basis for high-precision and efficient grinding with the shortest possible auxiliary times.
The S41’s wheelhead has an integrated B-axis that swivels automatically and enables the use of up to four grinding wheels. This enables workpieces to be completely machined in a single clamping with minimal auxiliary times and superior precision. The machine’s B axis has a direct drive which positions very quickly and precisely, whilst a high-resolution direct measuring system guarantees first-class repeatable accuracy of the B-axis.
Groupings of up to four external or internal grinding spindles result in that availability of more than 30 basic combinations. Internal grinding spindles with 6,000 rpm to 120,000 rpm speeds can also be used. Automatic balancing systems and frequency converters for the individual external grinding spindles enable even greater coordination of the wheelhead variants within the grinding process.
The availability of a wide range of workheads, including universal, chuck and direct drive chuck models, cover all users’ requirements. High-quality STUDER workheads are able to achieve a roundness accuracy during live grinding of 0.0004 mm and optionally 0.0002 mm. Simple cylindricity correction helps to achieve perfect results during live grinding, whilst customer-specific workpiece clamping and driving systems can be easily used.
Thread grinding operations are made possible by the S41’s position and speed-controlled C-axis that features a measuring system on its drive motor. Acceleration and grinding forces are absorbed through the excellent rigidity of the axis drives. The S41 enables axis-parallel grinding of conventional threads, through to the production of threads intended for high accuracy applications. STUDER also offers an automatically swivelling A-axis on the S41 with a standard swivel angle of ±15°for the efficient, high-precision thread grinding (as specified by Mazak). Greater pitch angles can be achieved with the aid of StuderThread software.
A generously dimensioned barrel, designed for the deployment of Morse 4 taper centres, glides freely in the S41’s tailstock housing, whilst centre pressure can be adjusted with the delicate precision required for the grinding of high-precision workpieces. The tailstock can be equipped with a hydraulically actuated barrel retraction for workpiece changeovers.
STUDER offers a large selection of dressing units to enable the dressing process to be carried-out flexibly and optimally. The S41’s grinding wheel profiles and dressing parameters are easily defined via macros. Another STUDER speciality is grinding wheel reference points (T-numbers), that enable programming with normal dimensions, which considerably simplify the creation of grinding programs.
Dave Fisher, Production Director at Yamazaki Mazak UK Ltd, concluded. “Over many years we have benefited from the accurate grinding results delivered by our STUDER grinders and also enjoyed excellent service from both STUDER and the company’s UK agent Micronz. We have been very impressed with the S41 technical developments, and the machine is now making a significant contribution to our high-precision grinding work. In addition we are grateful to the staff of both STUDER in Switzerland and Micronz for their help in the trouble-free specifying, installation and training of our new CNC universal cylindrical grinding machine.