# ELID Dressing Behaviors of Non-Abrasive Iron-Based Grinding Wheels
## 4 Discussion
### Comparison of Microscopic Morphology in Plate Glass Polishing  
The W1.5 grinding diamond wheel and non-abrasive iron-based grinding diamond wheel were subjected to electrical discharge shaping using the ELID technique, followed by ELID electrolytic sharpening. Subsequently, both the shaped and sharpened W1.5 grinding diamond wheel and the non-abrasive iron-based grinding diamond wheel were employed for the polishing of plate glass. The polished surfaces of the plate glass were examined using Atomic Force Microscopy (AFM), and the results of AFM testing for the plate glass polished with the W1.5 grinding diamond wheel and non-abrasive iron-based grinding diamond wheel are shown in Figures 12 and 13, respectively. Figure 11: Mechanical properties of the iron-based grinding wheel without abrasive particles. Figure 12: AFM test image of plate glass ground with w1.5 iron-based grinding wheel. Figure 13: _Cont._  
Figure 12 depicts the AFM microscopic morphology of plate glass polished with the W1.5 grinding diamond wheel. In Figure 12a, it is evident that the surface exhibits characteristics of plastic removal, with numerous plow furrows having widths of 1-2 \(\upmu\)m and depths ranging from 20 to 30 nm. Figure 12b shows the contour of profile 1 from Figure 12a, revealing a local surface roughness Ra of 11 nm and a maximum peak-to-valley height Rpv of 75 nm. Based on the analysis of the mechanical properties of the oxide film in the previous section, it can be inferred that the formation of these deeper plow furrows is due to the presence of abrasive particles obstructing the current during the ELID electrolytic sharpening process. On the abrasive-containing grinding diamond wheel surface, a continuous current path cannot be established, causing interruptions in the sharpening process. As a result, the oxide film distribution becomes uneven, leading to non-uniform mechanical properties. This non-uniformity in the \"spring force\" of the oxide film results in uneven forces acting on the specimen surface. Consequently, variations in the depth of scratches formed on the specimen surface occur, where areas without oxide film coverage experience greater \"spring force,\" leading to deeper scratches. Conversely, areas covered by the oxide film experience weaker \"spring force,\" resulting in shallower scratches on the specimen. Figure 13 represents the AFM microscopic morphology of plate glass polished with a non-abrasive grinding diamond wheel. In Figure 13a, it is apparent that the surface within the tested area exhibits characteristics of plastic removal. Figure 13b shows a local cross-sectional profile perpendicular to the grinding direction. The results of the profile test in the direction perpendicular to the grinding direction reveal a local surface roughness Ra of 2 nm and a maximum peak-to-valley height Rpv of 8 nm. There are no obvious deeper scratches observed. Figure 13c displays local pits, with depths of up to 15 nm, which are defects formed during the sintering process of the specimen. Based on the analysis of the mechanical properties of the oxide film in the previous section, it can be inferred that during electrolysis with the non-abrasive iron-based grinding diamond wheel, the absence of abrasives obstructs the current. As a result, the electrolytic sharpening process proceeds continuously, resulting in the formation of a well-performing oxide film. The oxide film is evenly distributed and possesses uniform mechanical properties, leading to excellent polishing performance. Material removal is uniform, resulting in an even distribution of scratches on the specimen surface with relatively shallow depths. In summary, the analysis indicates that when using an abrasive-containing iron-based grinding diamond wheel for ELID grinding of plate glass, the plow furrows formed on the specimen surface exhibit non-uniform depths. On the other hand, when employing a non-abrasive iron-based grinding diamond wheel for ELID polishing of plate glass, the plow furrows on the specimen surface have uniform and shallow depths.