1 B :1 Porosity Bond Bridge Abrasive Grain Vitrified-Bonded Wheel

2 B :2 Data taken from Peters, Snoeys & Decneut, The proper selection of grinding conditions in cylindrical plunge grinding, Proceedings of the 16 th International Machine Tool Design & Research Conference, MacMillan Press. Power normalized from Specific energy, grade approximation taken from The Shaw Hardness Method, Shaw, Principles of Abrasive Processing, 1996, eq. 5.13, Figure 121. stubborn-grit region Grits break out of bond material early. Keeps wheel sharp but gives poorer surface finish Bond refuses to release dull grits causing higher grinding power but a better surface finish due to the dull grits. quick-release grit region middle-of-the- road region Grinding Power 7 kW 6 kW 5 kW 4 kW 3 kW 2 kW 1 kW 0 kW Surface Finish, Ra 1.4 μm 1.2 μm 1.0 μm 0.8 μm 0.6 μm 0.4 μm 0.2 μm 0.0 μm HIJK Power in kW, GeneralSurface Finish Wheel Grade

3.... B :3 Making a grinding wheel is a bit like baking a cake. Consistency?Yes Logic behind the recipe?Well…. sort of. Sometimes.

4 F N : Normal Force F T : Tangential Force A dynamometer measures forces in three directions Source: J. Badger, Ph.D. Thesis, Trinity College, Dublin. B :4 How Are Grinding Forces Measured?

5 Normal Force Tangential Force As the amount of wear flat area increases, the relative amount of rubbing and plowing will increase. Consequently, normal and tangential forces will increase. Notice that normal forces increase at a higher rate than tangential forces. K K I I G G Passes Tangential Force (lbs) Normal Force (lbs) B :5 Kannappan, S. and S Malkin, “Effects of Grain Size and Operating Parameters on the Mechanics of Grinding,” page 834, figure 4 Forces vs. Time

6 C :6 width of cut in mm Material Removal Rate (MRR) – Q depth of cut in mm mm 3 s Material Removal Rate (MRR) = feedrate in mm/s depth of cut in mm width of cut in mm × × Material Removal Rate (MRR) = feedrate in inches/min depth of cut in inches width of cut in inches × × in 3 min

7 But that’s not what happened. The post-grinding run-out profile actually looked like this, in green. From the paper “Loading in Grinding: Chemical Reactions in Steels and Stainless Steels” by Badger, Murphy and O’Donnell, 2010 ISAAT Conference, Taiwan. After Grinding After Dressing mm One grit diameter mm 64 grit diameters 16 mm F :7

8 G :8 What’s the Root Cause of Residual Stress? 6) Therefore, the hot material will be under compressive stress (as it wants to be larger than it is allowed to be) strain Compressive stress Tensile stress

9 Single-Point Cluster Blade & Blade Fliesen Diamond Roll Form Roll Disk Rotary PCD Form Roll Overview of dressing tools H :9