Shapes

Tools are characterized by tool shape and abrasive layer composition. The tool shape specification follows DIN ISO 525 and DIN ISO 603, FEPA standards, ANSI B74.2 (conventional tools), or ANSI B74.3 (superabrasive tools) [DIN00a, DIN00b]. In addition, the wheel specification often includes company specific terms as well as the used standard. Table 4.1 shows typical categories in tool specifications.

Fig. 4.1 Bonded abrasive tools

The wheel dimensions are expressed in the form of “(outer diameter) x (thick­ness) x (inner diameter)”; for superabrasive wheels the layer thickness is added [MARI07, p. 46]. Many examples of tool shapes are shown by Marinescu et al. [MARI07, p. 46-48].

Layer width is important for grinding forces and achievable surface roughness. Cup wheels with a higher layer width can achieve significantly lower workpiece roughness than cup wheels with a small layer width due to the higher number of passes [JUCH78].

The abrasive layer is composed of abrasive grits, bonding, and pores (see Sect. 6.1 “Abrasive Layer Composition”). The volumetric composition of grits, bonding, and pores tailors the grinding tool application. The grits have to perform the cutting action. The bonding holds the grits together and releases blunt grits. Furthermore, the bond transfers the forces from the tool rotation and conducts process heat. The pores bring cooling lubricant to the cutting zone and transport chips away from it. The pores act as chip and cooling lubricant space and can be varied in number, size and total volume in a wide range via artificial pore builders.

Table 4.2 describes typical information contained in the tool designation. Marinescu et al. summarize examples of conventional wheel specifications [MARI07, p. 109] and of vitrified CBN wheel specifications [MARI07, p. 117].

“Structure” can be defined as a characteristic proportional to the distance between grits, but this definition just works for constant grit sizes [RAMM74]. These structure grades do not necessarily provide information about the porosity of the abrasive layer [RAMM74]. Abrasive layer structure is discussed in Sect. 6.1 “Abrasive Layer Composition”.