Flute Grinder Retrofit with SINUMERIK 802D at Sutton Tools Pty Ltd
Achieving Much Wider Range of Flute Shapes in Reduced Set Up Time


CNC Design has successfully completed a CNC retrofit project on a Normac Flute Grinder used for grinding flutes on drills and taps for Sutton Tools Pty Ltd. Originally the machine had two hydraulically driven axes and one grinding wheel. These axes were coupled by mechanical wedges, spiral screw and hydraulic compensation to achieve a flute shape for a particular drill bit. Dressing of grinding wheel was done with manual mandrel adjustment for diamond. This in turn made the machine only capable of supporting a limited range of flute shapes with long set up times for each shape.

"The objective for converting the Normac Flute Grinding machine was primarily to reduce set up time between jobs. Also to enable us to achieve a much wider range of flute shapes due to the CNC Dressing system, and improve the tool quality with better geometry and flute index. The conversion gives an updated machine with modern CNC controls, " revealed the Manufacturing Manager of Sutton Tools Pty Ltd, Phillip Xuereb.

The perfect motion control solution provided by CNC Design was a cost effective digital CNC system Siemens SINUMERIK 802D capable of driving 4 axes in conjunction with world wide proven Siemens servodrive SIMODRIVE 611Ue and 1FK6 AC synchronous servomotors.

The mechanical links between the axes were removed and 1FK6 servomotors were installed. Each axis can be controlled individually allowing for easy setup. The flute grinding cycle performs a three-dimensional interpolation between the infeed axis (X), the vertical axis (Z) controlling the grinding wheel height and the workpiece rotational axis (A). The fourth axis (Y) positions a new rotary diamond dresser motor, which is mounted to a new ballscrew driven cross slide. The dresser is positioned over the top of the wheelhead with its axis directly over the centre of the wheel head spindle.

The programming concept used was a template NC program that controls the machining cycle and calls a subroutine for dressing the wheel. When a part is being machined for the first time, the operator copies the template program and gives it an appropriate filename. Parameters in the file are modified to suit the required product and the file is then saved. This allows the operator to produce a library of parts, which makes it easy to change product.

The machine has been in production since mid March 2003 and is successfully producing a range of parts. Suttons Tools are pleased with the quality of the parts produced and the ease in set up and product change. "The conversion has meet our original specification and is now performing to our expectation. We will continue with the program of converting our other mechanical machines with CNC controls," Phillip Xuereb added. (17/06/03)