The Kellenberger Kel-Varia cylindrical grinding machines now incorporate a direct-drive workhead grinding of large, heavy parts.

The CNC-controlled universal grinding series is a product of Hardinge Inc., which emphasized the robust and rigid design of the workhead, making the grinding process both reliable and accurate for critical jobs.  Kel-Varia cylindrical grinding machines are designed for grinding large, heavy parts and non-round contours. Three sizes are available, with distance between centers of 600, 1,000 and 1,500 mm and center heights of 175, 225 and 250 mm, respectively.

A powerful torque drive means that production of heavy parts can be accelerated and braked quickly, and precisely, with zero backlash during bidirectional movements for increased productivity.

A wide range of parts and geometries can be processed using combinations of cylindrical grinding, OD and ID out-of-round grinding, thread grinding, and jig grinding — all in one set-up. Advanced C-axis (ultra-high resolution) operation makes it possible to perform precision grinding of grooves, and satellite and centering bores.

The direct-drive workhead has an infinitely variable spindle speed from 1 to 500-rpm (with Heidenhain control), with a maximum weight capacity of 750 Nm / 300 kg (660 lbs), and an optional ±60-second micro-correction for adjusting cylindricity is simple.

For machining between centers, a heavy-duty Morse taper 4 tailstock with nitride-coated sleeve runs in ball-bush bearings to achieve high in-feed rates, even with heavy parts. A sleeve retraction of up to 50 mm is pneumatically or hydraulically operated. Maximum weight is 250 kg / 550 pounds between centers.

The (C-axis) option of interpolating the X and C axes make it possible to use the cylindrical grinding machine for non-round shapes, such as polygons, free contours, and eccentric forms. The rotary encoder with a resolution of 0.00001° is installed directly on the workhead spindle.

All standard grinding cycles work on cylindrical and non-round grinding as well, including the handwheel release for the X-axis. Powerful motors and a fast control system (Heidenhain GRINDplus) ensure dynamic non-round and thread grinding operations. Jig grinding capability offers a complete part in one setup, an additional process that would have been done on a second grinding machine.