Хонинговальные головки

2.2.1 Uncut Chip Thickness or Grain Penetration Depth The starting point for any discussion on grinding parameters is “uncut chip thickness,” hcu, as this provides the basis for predictions of roughness, power, and wear [Shaw 1996]. Uncut chip calculations are typically based on representations of the material removed in the grind process as a long, Read more

1.4.1 Trend toward Higher Speeds Vitrified CBN wheel speeds have risen significantly in the last 10 years. In 1980, 60 m/s was considered high speed; by 1990, 80 m/s was becoming common in production; by 1995, the speed reached 120 m/s; and then by 2000, the speed was 160 m/s. At the time of this Read more

The hardness of diamond is a difficult property to define for two reasons. First, hardness is a measure of plastic deformation but diamond does not plastically deform at room temperature. Second, hardness is measured using a diamond indenter. Measuring hardness in this case is, therefore, akin to measuring the hardness of soft butter with an Read more

Depth of cut will also control roughness. However, the maximum dress depth should be kept under 30 pm for regular alumina wheels, after which the only change is increased tool wear. For seeded gel-type abrasives, the maximum dress depth should be under 20 pm. The minimum dress amount will depend on machine accuracy and stability, Read more

An increasingly popular approach to control thermal damage has been developed by Malkin [1989] with literature examples of its application in industry by General Motors on cast iron [Meyer 2001], with Bell Helicopter on hardened steel, and [Stephenson et al. 2001] on Inconel to impose a limit on grinding temperatures. Malkin [1989] provides the maximum Read more

Aircraft grade aluminum alloys are used as hub materials for some high-speed vitrified CBN. The obvious attraction is the lower density relative to steel. Various grades are available with tensile strengths of 120 to 140 kpsi. However, they have higher thermal expansion and appear to give more size and stability problems. 4.6.8 Junker Bayonet Style Read more

6.1 INTRODUCTION Wheel bond systems can be divided into two types: those holding a single layer of abrasive grain to a solid steel core, and those providing a consumable layer many grains thick with the abrasive held within the bond. The latter may be mounted on a resilient core or produced as a solid monolithic Read more

Crush ratio can have a profound effect on the dressing action. Ishikawa and Kumar [1991] reported a study on dressing of vitrified bonded wheels containing coarse grade 80# GE 1 abrasive. They distinguished between three forms of grit fracture: “micro,” “medium,” and “macro” as illustrated in the micrographs in Figure 7.21. It was determined that Read more

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 Read more

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%) • Read more