United Grinding Technologies is introducing a new universal grinding machine, the Studer favoritCNC, and promising “unheard of versatility for small budgets and high standards.” The machine is designed for grinding medium-sized workpieces in individual and serial production. With options in-process gauging, balancing systems, contact detection, and length positioning, as well as a grinding length of 25.6 in., a center height of 6.9 in., a workpiece weight of 176 lb., and a grinding wheel diameter of 20 x 2.5 x 8 in., the favoritCNC can be adapted for many grinding applications.
UGT is the North American arm of the Körber-Schleifring Group and supplies machine tools with several well-known brands, like Blohm, EWAG, Jung, Mägerle, Mikrosa, Schaudt, Studer, and Walter.
The bed of the new Studer machine is formed of solid Granitan S103 and equipped with high-quality components that ensure exacting precision, performance, and reliability.
The Studer grinding software, with ‘pictogramming,’ allows less experienced users to program grinding and dressing cycles quickly and efficiently. The optional StuderGRIND software is available too, and allows special applications to be programmed efficiently, such as profiling wheels for complex workpiece shapes.
Solid Granitan base
The Granitan mineral casting S103 structure developed by Studer has been well established for efficiency, and continues to be produced in the company’s own plant. Its dampening effect ensures outstanding surface quality of the ground workpieces. Also, it helps to extend the service life of the grinding wheel, reducing downtime. Temporary temperature fluctuations are extensively compensated by the thermal behavior of Granitan, which provides high stability for machining operations.
The V and flat guideways for the cross slides are molded directly into the machine base and finished with a non-abrasive Granitan S200 slideway coating. The patented surface structure prevents the slides from hydroplaning and eliminates the stick-slip effect, which may be found in conventional guideways, Universal Grinding noted. The guideways offer “the best possible accuracy throughout the speed range with high load capacity and dampening levels,” it said.
Longitudinal and cross slides
The longitudinal and cross slides are cast in gray cast iron and have “very precise” ground V and flat guideways, with the distance between guideways optimally suited to the machines overall rigidity. The slides rest on the guideways on the machine bed through the entire speed range, which the builder noted is the basis for the excellent straightness of 0, 0025 mm over 650 mm measuring length.
The slides are advanced by 40-mm-diameter circulating ballscrews connected to a three-phase servo motor via torsion resistant, bellow-type couplings. This allows the axes to achieve high process speeds on one hand, while short auxiliary times also guarantee maximum precision with in-feed movements of 0.0001 mm on the other.
Using the swiveling machine table on the longitudinal slide allows the whole length of the surface to be grounded and acts as a support for the workhead, the tailstock, and accessories and devices.
The turret wheelhead can be used for both external and internal grinding. It can be equipped with an extra grinding wheel and internal grinding spindle for this purpose. With extreme precision, the user can manually (2.5°) index the turret wheelhead in a Hirth gear within a swiveling range of -15°/+195°.
The grinding wheel dimensions are 19.69 in. diameter, 2.48 x 3.15 in. wide, and 7.99 in. bore. It has a drive power of 12 hp. The cutting speed maximum of 9,843 sfpm enables efficient removal values during the grinding process. The speed of the belt-driven internal grinding spindle can be infinitely variably regulated. Spindles are available with nominal speeds of 20,000, 40,000 and 60,000 rpm.
Tail stock — The barrel is well proportioned for the MT4 taper centers, and glides in the tail stock housing. The fine adjustment ensures taper corrections less than 1μm when grinding between centers. In order to guarantee optimal thermal stability, a cooling lubricant is passed through the tail stock, and covers the barrel and diamond holder completely.
Workhead — The universal workhead with MT5 fitting taper is capable of live spindle grinding and grinding between centers. The workhead spindle is mounted on roller bearings, in low maintenance and processes a roundness accuracy of the below 0.0004 mm. The fine adjustment allows for cylindrical corrections in the 1μm range during live spindle operations. Extreme run-out accuracy is 0.000016 in., chucked or between centers. The workhead provides 1-1,500 rpm for the right speed for each application.
Machine control — The Fanuc 0i CNC with active flat-color monitor (10.4 inches) is reliable and optimized to the drive elements. All controls are clearly and ergonomically arranged, and the optional Sensitron electronic contact detection function allows downtimes to be minimized.
Pictogramming functions allow operators to string together the individual grinding cycles, and the control system generates the ISO code. Grinding and dressing process sequences can be programmed freely to optimize the grinding process.
The StuderGRIND programming software is available for special applications, such as profiling the grinding wheel for complex workpiece forms. The program is created on the PC and transfers directly to the machine control unit.
UGT’s universal, external and internal grinders are supported by grinding specialists and technicians, drawing on the experience with over 10,000 machine installations and a global support and service network.