Manufacturing of the abrasives corundum and CBN is described in Chap. 2 “Abrasives”. The energy consumed in their primary production can be estimated
|
Grinding wheel width |
20 mm |
20 mm |
|
Outer diameter |
400 mm |
400 mm |
|
Inner diameter |
200 mm |
200 mm |
|
Segment length |
— |
31.4 mm |
|
Segment height |
— |
5 mm |
|
Number of segments |
— |
40 |
|
Fig. 8.2 Examined grinding wheels |
with a maximum value of 54.7 MJ/kg for alumina (99.95 % purity) and a maximum of 133 MJ/kg for HBN (Table 2.9) [GRAN12]. HBN is the basic raw material to produce CBN. Expert interviews indicate that the synthesis of CBN from HBN consumes presumably much less energy than the initial HBN production, so the energy values for HBN are taken as estimation for CBN in this study.
Table 8.1 shows the composition of a representative vitrified bond including the proportion of ingredients within the bond, densities, and embodied energies from raw material processing. Here the bond ingredients are not added as frits, which would lead to additional embodied energy, because frits have additional preprocessing steps (see Sect. 3.2.2 “Manufacturing of Vitrified Bonds”). In industry, the bond composition can be adjusted precisely to the abrasive type, desired wheel properties, expertise of the particular manufacturer, etc. Table 8.1 leads to an assumed embodied energy of 43.3-54 MJ/kg for the bonding mixture. Table 3.5 gives more information on environmental and health properties of critical bond ingredients.