Evolution not revolution

Shoppers going about their daily tasks in the town of Thun, Switzerland, saw a rather unusual sight at the end of January – a Studer universal grinding machine; the S41, in fact, which, says its maker, sets new standards of accuracy and precision. Image: While you're out shopping, could you pick up a new grinding machine, too? Thun is about 20 miles south and 10 miles east of Bern, and is at the west end of lake Thunar See – Interlaken is at the eastern end. It nestles in the shadows of the Bernese Alps. The town is home to cylindrical grinding machine maker Fritz Studer, to give it its full name, and is well known to the locals; besides, Studer employs some 800 people, so it is no small concern for the circa 42,000 population location. The sight of a machine tool in the city centre was unlikely, therefore, to have been too much of a shock, although was unlikely to have been a big deal for most. Image: The picturesque town of Thun, home to grinding specialist Fritz Studer Mac Launched on 27 January, the S41 is, however, a big deal for Studer and for its customers. In addition, its launch highlights the tenacity of this 99-year-old machine tool firm, following the most savage of economic conditions. Such was underlined last year at this annual event by the adoption of the St Bernard dog as the motto – pointing up the company's tenacity and endurance in withstanding the economic storm. Well, it has clearly weathered events, making no losses during the downturn, either, Stephan Nell highlighted, speaking as chairman of the board of directors of Studer*. Investment in machine development, buildings and equipment continued throughout, he added, although managing director, Studer* Michael Horn did say that government support, in terms of wage subsidy, was a key element in helping the company through this period. (* See box item for management position update) Image: Even during the downturn, Studer saw no losses, said Stephan Nell The S41 represents evolution not revolution, however, and evolution – "making the good even better" - was the theme for this year's event, with this graphically underscored at the press event, literally, by a series of artworks created in real time, accompanied by live harp music. Both in keeping with Studer's 'art of grinding' tag. The new machine is the successor to the S40 CNC, which has sold almost 1,000 units since launch in 1992; but the S40 itself drew on an evolution of technology stretching back decades, it was underlined. To highlight the precision of the new machine in a novel manner, Studer gave the example of two parallel lines travelling around the globe – the divergence error for Studer was put at 19 m, while for competitor machines it was put at 70 m. Image: The S40 CNC has sold almost 1,000 units. But even as market leader, it has been replaced….. Image: ….with the new S41, which sets new standards in precision, says Studer The S41 represents five years of development, with Fred Gaegauf, managing director, Studer, technology, emphasising that the design has seen physical testing of three complete machines covering 50 months, or around 8,000 hours. "That's more then the number of hours that Airbus tested its A380 for," he offered, by way of tongue-in-cheek comparison (10 planes; 4,500 hours). Essential components were already under test in 2007, with the first machine put into test in 2008, the second in 2009, while a third went to workholding specialist Schunk in 2010, he added. Yet the S40 was by no means out-dated, it was still the market leader, Mr Gaegauf said, but the decision to move to a new model has to be taken, if the 'customer wish list' that builds over time is to be sensibly implemented. Headline improvements, then, are that the circularity and stepping performance of CNC interpolation of X and Z axes is 65% better than the S40; accuracy is improved by 20%; parallelism is 1.5 micron over a Z-axis distance 1,600 mm (although 4 micron is the publicly claimed figure), while it guarantees Studer guarantees a straightness of <3 microns over 950 mm; roundness during live spindle operations is 0.0004 mm (optionally 0.0002 mm); rigidity is 40% higher; and stiffness and damping are superior. A number of key elements underlie this performance. While the machine employs a Granitan S103 bed, as do all other Studer grinding machines, this bed is said to be more solid, more rigid and more thermally stable than was the S40's. Image: Granitan is the foundation of Studer's success, literally, here shown in the form of the S41's bed The guideways of both the longitudinal slide and the cross slide are moulded directly into the machine bed, ensuring that high grinding forces are absorbed into the machine bed, plus the guideways are spaced further apart. The machine features the StuderGuide guideway system (patent pending), which employs the advantages of hydrostatic and hydrodynamic guide systems and avoids the slip-stick effect or floating of the slide. Linear motors, from Swiss company Etel (www.etel.ch), are employed to drive the X and Y slides; resolution is 20 nanometres and rapid traverse is 20 m/min - 4 times faster then before. (Studer's S12, launched in 2005, was the precursor for this development, it employing novel guide and linear motor technology). Image: The S12 was the precursor for the S41's new guideway and linear motor drive system Additionally, the solid gray cast iron longitudinal and cross slides rest completely on the guideways over the entire travel. The longitudinal slide (Z-axis) has a ground work table which carries the workhead and tailstock, as well as additional accessories and devices. A ground T-slot over the entire length of the guideway enables optimal positioning of dressing tools. The cross slide (X-axis) supports the wheelhead. The swivel movement of the turret wheelhead (B-axis) is also by a direct drive. It swivels the turret wheelhead around three times faster (270° in 2.6 sec) and positions the new grinding wheels in a much shorter time, with a positioning accuracy of < 0.1 sec of arc - the S40's figure was 0.25 sec of arc. The elimination of the Hirth gear, which fixed the wheelhead in position on the predecessor machines, also contributes to faster positioning, since it is no longer necessary to lift the turret wheelhead out of the Hirth gear first of all, and then to engage it again by lowering it. Image: The new wheelhead in just one of its many configurations. Indexing speed and positional accuracy are far better than for the S40 Improving the machines capability to undertake more operations or handle larger workpieces are a number of other characteristics: centre height has been increased to 225 mm as standard, with a centre height of 275 mm an option; distance between centres is 1,000 mm as standard, but optionally is 1,600 mm; workpieces up to 250 kg can now be machined; an hydraulically clamped tailstock supports heavier workpieces; up to four external grinding wheels or three internal grinding spindles enable over 30 grinding head combinations; grinding wheels are no longer driven by belt drives, but only by motor spindles; external grinding wheels up to 500 mm diameter can be used; 15 kW motor spindles able to support 50-80 m/sec wheel speeds feature; motor spindles for high speed grinding (HSG, 140 m/sec, 30 kW drive, 400 mm diameter wheel) can be fitted; internal grinding spindles with speeds from 6,000 to 120,000 rpm can be used; automatic balancing systems and frequency converters for each external grinding spindle allow the grinding process to be specifically matched to the respective conditions of use; C-axis for form grinding; and wheelhead variants are also available with a vertical spindle for grinding keyways or with a traverse grinding axis for traverse grinding of internal tapers. Attention has also been paid to making the machine easier to use. Fatigue-free working and straightforward machine operation are supported by, for instance, the virtual elimination of hoses and cables from the work area, grinding wheel change is performed with a single Allen wrench, and a special small crane is integrated into the machine, so that heavier grinding wheels do not have to be lifted manually. Fitted with a Fanuc 31i-A machine control with integrated PC, this has allowed the integration of StuderGRIND software (see http://www.machinery.co.uk/article/13546/Virtual-advantage.aspx), which supports the generation of grinding process parameters, and the StuderWIN operator interface. (The S33 also has integrated StuderGRIND software.) A software package to support fine tuning of wheel dressing is also offered. [] Box item 1 – management changes [] Box item 2 – Business performance [] Box item 3 – Production, logistics and investment Box item 1 Management changes Stephan Nell, chairman of the board of Fritz Studer AG and the Cylindrical Grinding Technology Division, became managing director, Körber Schleifring GmbH (Fritz Studer's parent) on 1 February 2011, where he assumes responsibility for sales, marketing and service. He also becomes managing director, Fritz Studer. Michael Horn, previously managing director, Fritz Studer, will succeed him as chairman of the Fritz Studer board and the Cylindrical Grinding Technology Division. He also becomes a member of the management board of Korber Schleifring. Fred Gaegauf remains managing director, Fritz Studer, technology. Peter Weber has been appointed managing director, Fritz Studer, responsible for sales, marketing and service. The two companies in Korber Schleifring's Cylindrical Grinding Technology Division - Fritz Studer and Schaudt Mikrosa - will be under joint management in future, with Michael Horn, Fred Gaegauf and Peter Weber overseeing this. Box item 2 Business performance Studer reports that it saw a pickup in incoming orders from Asia at the beginning of last year, and it actually achieved record incoming orders in individual markets. With a pickup later in the year in other markets, the company's target for incoming orders for 2010 was exceeded, and it is thus able to start 2011 with a corresponding order backlog. The company expects to outperform the 20% growth forecast for its market segment this year, winning market share from competitors, although the strong Swiss Franc is a hindrance. Turnover for 2011 is expected to be over £130 million - above the level of 2006, that is, while for 2012, Mr Nell says that turnover will be back to 2007 levels, which was one of "two or three of the best years in the history of the company". In 2008, Studer undertook a joint future with the former Combitec, in nearby Biel. Even during the recent difficult period, a record for Combitec internal grinding machines sales was achieved, and the company says it will endeavour to set another new record in 2011. Overall, across all product lines in internal grinding, Studer claims the position of world market leader. Studer produced 350 machines last year (under the Studer name, excludes Combitec and Schaudt Mikrosa units), with the main proportion taken by the S31, S33 – including the favoritCNC and ecogrinder - and, the S40. The company is planning for 550 Studer machines this year - 700 including Combitec and Schaudt Mikrosa. The company plans to make 60-70 S41 units this year. Box item 3 Production, logistics and investment Last year, Machinery reported that Studer had undertaken a continuous improvement initiative under the name of PULS (see article here). This has informed the manufacture and assembly of the S41. The new machine will be assembled according to flow-line principles, although it is the men and resources that move to the static machine (S33 sees the machine moved). Assembly is broken down into 10 equal cycles. A reduction in assembly time of between 20-30% should be possible, says Mr Gaegauf. Studer has continued to invest throughout the downturn. Investment in 2010 saw completion of major construction activities. The factory development project begun in 2008 has been successfully completed, according to plan. The company will also make substantial investment in 2011, with the focal points being in the area of production and spare parts procurement. Last year, Studer highlighted its strategic goal, the manufacture of core components and the targeted expansion of key processes in the machining area. In line with this goal, the company is investing in super fine milling and high precision spindles, and will design and procure the necessary machines this year. As is typical after a downturn, the supply of parts from external sources runs into trouble on grounds of capacity to supply. Lead times for some parts have increased by 70%, it is highlighted. Ballscrews, CNCs and measurements systems were parts mentioned specifically. The company is variously working with existing suppliers on a detailed plan of supply; in-sourcing production; and developing new procurement markets, including China. First published in Machinery, March 2011