Хонинговальные головки

Nonporous superabrasive cannot, in general, be dressed with diamond tooling. Truing can be performed for some softer CBN bonds, such as resin, using diamond nibs or rotary diamond traversing discs, but, in general, most wheels are trued and conditioned using conventional abrasive blocks or wheels. In the case of diamond, this can sometimes be completed […]

Common roughness specifications (marks) on part drawings are shown in Figure 2.7. This gives both the current standard practice, especially in Europe, and the older machining marks still seen Cross-hatch grind pattern from a Concentric rings grind pattern from a face grind operation, e. g., shoulder plunge or angle approach shoulder kiss or double disc […]

3.7.1 Indentation Tests Fundamental mechanisms of crack formation and spreading in the case of brittle-hard materials were carried out by Lawn and Wilshaw [1975]. The stressing of a ceramic surface with a cutting edge causes hydrostatic compression stress around a core area in the subsurface of the workpiece. This leads to a plastic deformation of […]

Holding the abrasive section together on the wheel body has already been discussed. A second problem is how to hold the wheel body on the machine spindle. Centrifugal forces cause the wheel to expand radially both on the outer diameter and the bore. It, therefore, must also contract axially. The problem is, therefore, to prevent […]

As with all new technologies, it took significant time and application knowledge to understand how to apply SG. The abrasive was so tough that it had to be blended with regular fused abrasive at levels as low as 5% to avoid excessive grinding forces. Typical blends are now • 5SG (50%) • 3SG (30%) • […]

Interestingly, GE also developed a grit-type GE 550 that is a microcrystalline product; this could be considered the “SG” of CBN grains. It is extremely tough and blocky and wears by microfrac­turing. However, just like SG grains, it also generates high grinding forces and is, therefore, limited to use in the strongest bonds, such as […]

Diamond reacts with air at temperatures above 650°C. Therefore, the wheels must either be fired at low temperatures, or in an inert, or reducing, atmosphere. Very low temperature bonds, however, FIGURE 6.10 Hot pressed fully densified vitrified diamond bond structure. FIGURE 6.11 Typical application for a porous vitrified fine grain diamond structure wheel-grinding of polycrystalling […]

7.3.1 Introduction Perhaps the most widely sought after, but as yet unavailable, stationary tool is the one that can dress high-performance vitrified cubic boron nitride (CBN) wheels. The problem is that single­point and needle diamonds wear much too quickly for most superabrasive wheels at the speeds the wheels must operate. Grit tools leave the wheels […]

8.1 INTRODUCTION 8.1.1 Loss of Accuracy and Productivity Vibrations can cause serious problems in grinding processes leading to loss of machining accuracy and loss of productivity. Of the various types of vibration, chatter vibration is one of the most crucial ones because it reduces form accuracy as well as increasing surface roughness of the ground […]

Grinding, once considered primarily a finishing operation involving low rates of removal, has evolved as a major competitor to cutting, as the term “abrasive machining” suggests. This is what Milton Shaw, the man who is considered the great pioneer and father of American grinding, said about 10 years ago. Shaw led the development of grinding […]