V - The magazine of the VOLLMER Group - 2019

4 5 6 SWEET SPOT AND AGGRESSIVENESS In the grinding industry, the term “aggressiveness” means the penetration depth of the diamond grain and therefore the maximum thickness of the grinding chips (Image 4) . The rule is, the higher the aggressiveness, the deeper the grains pene- trate. Therefore the lower the aggressiveness, the less the penetration depth. You can calculate the amount of aggressiveness: AGGRESSIVENESS CONCEPT The penetration depth is easy to influence by changing one or more of the follow- ing parameters: Cutting speed, feed, cutting depth and grinding wheel diameter. If, for example, you increase the feed, the cycle times reduce and the aggressiveness increases. This causes strong forces to impact on the grinding grain, which can lead to more wear and grain breakage (Image 5 and 6) and to other problems too. If, however, the cutting speed is increased simultaneously, you get good results. This is how you find and retain the grinding wheel's sweet spot – that is, the aggressive- ness that is most suited to the current application. This results in many advantages for you, such as an increased feed, avoiding grinding burn and less wear. ROLL THE FILM: Dr J. Badger on aggressiveness 4 OUT OF THE BINDING Excellent diamond grinding corns are a foundation for aggressiveness. 5 TOO MUCH AGGRESSIVENESS Carbide particles were ripped from the workpiece. An unacceptable result. 6 EDGE ROUGHNESS Looks acceptable like this. x Aggressiveness count = x Tool speed in mm/min Material removal rate in m/s Cutting depth in mm Grinding wheel diameter in mm √ 16.7 22 FEED