CBN tool grinding

Rollomatic has developed a dynamic method for grinding rotary cutting tools with PCBN cutting edges. This method uses a resin/metal bonded diamond grinding wheel for PCBN tools with a diameter between 1 mm and 3 mm.

In order to develop the right grinding strategy, experiments were done to find the correct parameters by grinding a straight endmill with corner radius and a helixed ball nose endmill, both with a diameter and  cutting length of 2.5 mm. These were performed on the GrindSmart® 628XS, equipped with a dressing unit and Gap Control. Two acoustic-emission (AE) sensors are needed to grind PCBN tools in a fully automated way. One is mounted on the dressing unit and is used to approach the grinding wheels with the dressing wheel, and the second AE sensor is used for the automatic wheel teach.

Rollomatic also recognizes a need for larger tools (diameter around 10 mm) with PCBN cutting edges, where the cost of PCBN prevents to grind the tools out of full material; instead inserts are brazed on prepared carbide shanks. We are currently developing additional grinding strategies for these larger tools for the GrindSmart 6000XL, also equipped with a dressing unit and gap control. The hydrostatic bearings of this machine will produce better surface finish compared with traditional grinding machines using ball-screw bearings.