Maximum Grain Depth Of Cut Research Articles

A Physics-Based Predictive Model for Number of Contact Grains and Grain Depth of Cut in Honing

Honing is a material removal process widely used in manufacturing of engine cylinders, compressors, valves, bearings, and hydraulic cylinders. The surface topography generated by honing has a profound effect on the tribological performance of the honed surface, since the cross-hatch pattern on the workpiece surface can be used to retain oil or grease to ensure proper lubrication and minimize wear. The number of contact grains and the grain depth of cut are important indicators of interactions between the tool and workpiece in the honing process. They are helpful in understanding chip formation, tool wear, and optimization of the cross-hatch pattern to improve the tribological performance of the honed surface. This article presents a physics-based model for predicting the number of contact grains and the grain depth of cut in honing. It describes the model development and studies the influences of abrasive grain size, abrasive concentration, nominal contact area, yield strength of workpiece material, and static load on the number of contact grains and the maximum grain depth of cut. Results from pilot experiments are used to verify the model.

Optimization of Cutting-Edge Truncation in Ductile-Mode Grinding of Optical Glass

The effect of cutting-edge truncation on the grinding mechanism of quartz glass as a hard and brittle material was investigated. From computer-aided grinding simulations and experiments on surface plunge grinding it was found that cutting-edge truncation decreases the ground-surface roughness and the maximum grain depth of cut; however, the maximum grain depth of cut approaches a constant value depending on the grinding wheel specifications. The alternative means of making the maximum grain depth of cut much smaller than this constant value is to increase the speed ratio. Cutting-edge truncation should be terminated at the optimum truncation depth to avoid the high grinding forces resulting from the flattening of cutting edges.

An Experimental Study on High Speed Grinding of Granite with a Segmented Diamond Wheel

An experimental study was undertaken to investigate the grinding of granite at different grinding speeds over a wide range of material removal rates. A metal-bonded diamond blade was used as the grinding wheel with natural gray granite as the workpiece material. The tangential and normal force components were obtained through measuring the horizontal and vertical force components as well as the consumed power. The experiments were conducted with a constant wheel surface state to study the influence of grinding speed under different material removal rates. An additional test was also carried out to examine the grinding process while the wheel surface state progressively changed, in which case both forces and the morphologies of diamond grains were monitored at regular intervals. At a fixed material removal rate, both the tangential and normal forces reduced slightly with the grinding speed. But the specific energy increased greatly at higher grinding speeds especially at a shallower maximum grain depth of cut.

Effect of cutting edge truncation on ductile-regime grinding of hard and brittle materials

Cutting edge truncation is a micro-truing process in which the diamond cutting edges of a grinding wheel are truncated and aligned at the same height. This process has been applied to the ultraprecision grinding of hard and brittle materials in order to improve the ground surface roughness. However, the theoretical investigation has not been clarified. In this study, computer simulation of surface plunge grinding has been performed. It is found that a surface roughness in the nanometer order can be generated by the truncation of a coarse-grained grinding wheel, but the contribution of such truncation to a decrease in the maximum grain depth of cut is insufficient. Thus, the proper selection of a fine-grained grinding wheel as well as suitable grinding conditions are necessary for ductile-regime grinding, which requires the maximum grain depth of cut to be less than a value realising ductile-mode material removal.

2618 切れ刃トランケーションを施した研削ホイールによる研削プロセスのシミュレーション(S74-2 砥粒加工(2),S74 砥粒加工)

Cutting edge truncation is a micro-truing process in which the diamond cutting edges of grinding wheel are truncated and aligned at the same height. In this study, surface plunge grinding has been simulated to clarify the effect of cutting edge truncation on the grinding mechanism in terms of the maximum grain depth of cut and finished surface roughness. It is found that a surface roughness of nanometer order is possible to generate by the truncation of a coarse-grained grinding wheel but the contribution to a decrease in the maximum grain depth of cut is not enough, so that proper selection of a fine-grained grinding wheel as well as suitable truncation are necessary for ductile-regime grinding, which requires the maximum grain depth of cut less than a value realizing ductile-mode material removal.

Grindability of Various Silicon Nitride Ceramics

The grindability of various silicon nitride ceramics ground using different diamond grinding wheels was evaluated in terms of specific grinding energy and strength degradation. Main results are summarized below. (1) Specific grinding energy increases with increasing hardness of the workpiece material using a grinding wheel of small grain size under the condition of small wheel depth of cut. (2) Strength degradation increases with a grinding wheel of large grain size. Degradation increases with a smaller material constant of the critical indentation radius: E⋅Kc2/Hv3 (E: Young's modulus, K1c: fracture toughness, Hv: Vickers hardness). (3) The degradation increases with increasing mean value of maximum grain depth of cut. The strength in the region of a large mean value of maximum grain depth of cut decreases with a larger material constant of crack extension length: Hv1/4/Kc.

Relationship between Strength Degradation and Grain Depth of Cut during Grinding Si<sub>3</sub>N<sub>4</sub>

The strength degradation of silicon nitride ceramics up-cut surface ground under different conditions were studied by specific grinding energy and maximum grain depth of cut statistically analyzed by new direct evaluation method of successive cutting point spacing. Main results are summarized as follows; (1) Strength decreases with increase in wheel depth of cut and with decrease in specific grinding energy, and dose not depend on the change of table speed under the grinding conditions with a wheel including large grain size (#100; grain diameter=125-150μm). (2) Strength degradation is much large by 70-80% compared to inherent strength of the work at the range of more than 0.5-1.0μm in mean value of maximum grain depth of cut.

Surface Grinding Characteristics of Si<sub>3</sub>N<sub>4</sub> Ceramics under High-Speed and Speed-Stroke Grinding Conditions

Si3N4 ceramic specimens were ground under different conditions with high-speed (wheel speed: 55m/s) and speed-stroke (table speed: 45-90m/min). The grindability was evaluated by grinding force, specific grinding energy and grinding ratio in comparison with conventional surface grinding. The strength degradation and surface roughness of ground workpieces were examined. The main results are summarized as follows. (1) This grinding conditions showed lower normal grinding force and specific grinding energy in a higher stock removal rate. And, the strength degradation and the surface roughness were not changed significantly even by increasing stock removal rate. (2) The lower normal grinding force and specific grinding energy were caused by a lower mean value of the maximum grain depth of cut. (3) This grinding conditions showed lower specific grinding energy in increasing stock removal and higher grinding ratio.

Statistical Analysis for Grinding Mechanism of Fine Ceramic Material

Si3N4 ceramics were surface-ground under different conditions, and the grindability was evaluated by specific grinding energy and stock removal rate. Statistical analysis was conducted on the specific grinding energy and stock removal rate with respect to the maximum grain depth of cut by a new method of directly evaluation successive cutting point spacing. Main results are summarized as follows; (1) The specific grinding energy decreases with increasing stock removal rate. This result shows that the fraction of brittle fracture of Si3N4 increases with increase in the stock removal rate. (2) By a new method for determining successive cutting point spacing, a difference in distribution of cutting edges between resinoid-bonded and metal-bonded wheels with the same grain size and concentration was evaluated. Furthermore, the maximum grain depth of cut of each wheel was represented by statistical analysis. (3) Decrease in the specific grinding energy was caused by the increase in statistical mean value of the maximum grain depth of cut. The stock removal of Si3N4 including brittle fracture was observed even at its level less than 1μm.

Formulation for the Effect of Surface Grinding on Strength Degradation of Ceramics

Relationship between fracture strength of ground ceramics and maximum grain depth of cut, g, has been formulated. The strength was expressed by an exponential function of g. This expression is based on the assumption that the crack depth of the ground specimen is represented in terms of normal grinding force applied with a single abrasive grain of a wheel, as median crack length in indentation fracture is the function of indenting load. The four-point bending strength of sintered silicon carbide ceramics ground with 4 kinds of grit diamond wheels under various conditions showed good agreement with the approximation by the function of g. In particular, the strength decreased steeply from the inherent level with a slight increase in g.