For 20 years now, the firm Kellenberger has been part of the Hardinge Grinding Group. From the very start, the VARIA universal cylindrical grinding machine model range has stood for the best in working and surface quality among Kellenberger’s range of products. More than 1000 machines are already in use around the world. The VARIA machine concept, constantly been updated with new developments and has always been a step ahead of the various technical standards. But now, with its larger work space, distinctly longer machine table, and the distance between centers of 63 inches (1600 mm), it is ready for even more comprehensive grinding possibilities.
Optimized for a demanding range of applications
The VARIA’s features are aimed at the demanding requirements involved in the high-precision production of prototypes and small and medium-size production batches. Typical areas of use include machine construction, the production of tools and molds, and the production of precision components for the automotive, electronics, and aircraft industries, and job shops with their wide variety of needs.
Hydrostatic guideways have always been a feature of the VARIA universal cylindrical grinding machine, providing the best in form accuracy for all grinding tasks involving interpolating axes. The newest generation of hydrostatic guideways in the VARIA is the result of 25 years’ experience. They provide excellent damping, stick-slip-free operation, high rigidity, and a constant machine temperature, resulting in outstanding surface quality and productivity and more process and operation reliability, without any friction loss and wear. Because of the direct drives on the rotary axes, high positioning speeds and accuracy are guaranteed.
Stability is crucial for achieving high precision and productivity. In the new VARIA, the solid machine table with the reinforced machine bed once again improves rigidity. The increase in stability means VARIA can now work with workpieces of up to 661 lbs. (300 kg).
With larger heights of and distances between centers, the new VARIA is faster and more precise, offering consistently better performance resulting in improved productivity. Drives optimized for performance move the longitudinal and cross slides at speeds of up to (787 IPM) 20 m/min., and at an axis resolution of ten Nanometers.
The hydrostatic B axis is equipped with a direct drive too. Allowing the revolving wheelhead to rotate roughly three times as fast as without a direct drive, and positions with a precision of less than one arc second. Allowing the reduction of non-productive times, so it raises productivity, especially when the work at hand demands the use of multiple grinding wheels.
Unique machine concept
The VARIA is available with distances between centers of either 39.4 or 63 inches (1000 or 1600 millimeters), and heights of centers of either (7.8”/9.9”/11.8”) 200/250 or 300 mm, as required. Travel on the X axis and Z axis is extended. Due to the modular machine concept, the task at hand defines the position of the wheelhead within the machine, and this way ensures an optimum in distance and dressing conditions. More than 30 wheelhead variations with external and internal grinding spindles permit an array of grinding possibilities, and the right application-specific configuration at all times.
The VARIA is equipped with the latest Heidenhain GRINDplus640. In addition to the Heidenhain controls with user-guided ISO programming and selective help images, for the first time Kellenberger has its controls, with a graphical programming and collision monitor. The controls allow faster-working speeds at even higher precision. Axis control in the Nano range translates into highly accurate profiling and track accuracy for contour grinding. Optionally, the VARIA can be equipped with the Fanuc 31i, as in previous models. The new remote maintenance concept with integrated IT security ensures higher security when connecting to the customer network via VPN tunnel or mobile communication.
Low-pressure hydrostatics and a new, optimized cooling system with bypass regulation valve are two of many new features. Proven features of VARIA machines include low-friction linear axes, back lash free spindle drive, drives optimized for performance, thrifty valve technology, a circulating lubrication system with no oil loss, and options to switch off unused features.