Relationship between surface roughness and subsurface crack depth during grinding of optical glass BK7

Fang

Chen

et al. 2015

Subsurface damage (SSD) induced during abrasive grain machining process strongly influences the mechanical strength and subsurface quality of the brittle components. Therefore, it is meaningful to study the relationship between SSD and grinding parameters. The methods of theoretical analysis, numerical simulation and experimental testing are used to analyze the SSD of brittle materials in high-speed grinding. The results of numerical simulation are consistent with those of theoretical analysis and experimental testing, which indicates that the present numerical method is reasonable. The investigation focuses on the effects of wheel speed, grinding depth, and apex angle of the abrasive grain on the SSD of brittle materials. It shows that when maximum undeformed chip thickness (M-UCT) is greater than the critical thickness of brittle fracture, the material removal is mainly in the brittle mode. A high wheel speed is beneficial to achieving a good subsurface quality. However, under certain conditions, an ultra-high wheel speed with quite small grinding depth is not helpful in SSD control. Due to the kinematic characteristics of the grinding process, the effect of grinding depth on SSD is weaker than that of wheel speed and a smaller abrasive grain is of advantage to subsurface quality. In addition, the grinding force is one of the major factors influencing the subsurface quality.

Section: Depth Of Subsurface Damagementioning

confidence: 99%

Section: Depth Of Subsurface Damagementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Subsurface damage in high-speed grinding of brittle materials considering kinematic characteristics of the grinding process

Fang

Chen

et al. 2015

“…Yao et al [15] researched the relationship between subsurface damage and surface roughness of grinded BK7 glass. The predicted values by this relationship presented an acceptable match with experimental results.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on grinding characteristics of optical glass BK7: with special emphasis on the effects of machining parameters

2015

As a kind of widely used optical material, optical glass BK7 is machined by first grinding and then polishing in industrial production. However, the polishing process is timeconsuming and high-cost. Therefore, it is very meaningful to produce high-quality BK7 workpieces by grinding. To understand the grinding characteristics of BK7, many studies were conducted and reported. But most studies available so far had low industrial relevance and were difficult to be applied to guide real production of BK7 glass. To fill this gap, in this study, BK7 grinding characteristics are investigated and special emphasis is laid on the effects of machining parameters in terms of machined surface morphology, subsurface damage, and grinding force. Results show that wheel depth of cut plays the most important role in BK7 grinding, and a little difference of it leads to completely different material removal modes. Wheel speed is the second important parameter. It cannot change the dominant removal mode but can slightly adjust the characteristics of machined surface, subsurface damage, and grinding force. Workpiece feed rate has a small impact on BK7 grinding. From the viewpoint of industrial application, it suggests that the wheel depth of cut of 1.0 μm, high wheel speed, and high workpiece feed rate are more rational and practical because under this condition the grinding process can produce BK7 workpieces, which possess crack-free surface and sublet subsurface damage, with high removal rates and stable grinding forces. The findings of this paper are expected to be meaningful to provide the experimental references for the studies of the BK7 grinding process and guide industrial production of BK7 optical components.

“…Despite a lot of efforts have been made to investigate the impact of the grinding process parameters on SSD, most of the works mainly focus on how the grinding process parameters influence the surface roughness or the depth of SSD (micro cracks) of high-precision optical components [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Relationship between grinding process and the parameters of subsurface damage based on the image processing

Hong-feng

et al. 2015

Grinding is the main process step for the highprecision optical components, and its process parameters may bring forth subsurface damage to some degrees on the surfaces and finally result in the variation of the mechanical and optical properties of the components. In this paper, the ground sample is etched to expose the micro cracks and the characterization parameters of the subsurface damage are extracted using the image processing method. To investigate the influence of main grinding parameters on the micro cracks of subsurface damage, relationships among the average abrasive size, grinding force, wheel speed, and grinding depth and characterization parameters (length, angle, and density) of micro cracks are established. The results show that the influence of grinding parameters on the micro crack's length is consistent with that on the surface roughness. The average abrasive size and grinding force have obvious influence on the subsurface damage and surface roughness than wheel speed and grinding depth. Micro cracks' angle and density are almost not affected by the grinding parameters.