Manufacturing Energy of the Steel Body for Superabrasive Wheels

This case study assumes that the body of the superabrasive wheel is made of tempered low alloy steel 42CrMo4 (oil quenched). This steel offers a high strength along with good durability and advantageous thermal characteristics.

First, the steel is cast into a round steel bar of a diameter of 394 mm. Then the bar is forged and rough rolled. A sawing process follows in which blanks of 25 mm

thickness are produced. Because the sawing blade (5 mm width) produces waste, the casting energy and rolling energy has to be calculated for blanks with 30 mm thickness. Table 8.6 shows the respective energies for casting and rolling. The sawing process can be estimated with the values in Table 8.7 to account for a maximum energy of 17.6 MJ per steel body. This is an upper boundary for a not optimized sawing process.

The steel cylinders are then machined to the desired final shape through different turning processes. With coarse machining the outer diameter of 394 mm is reduced to 390.2 mm, the body width is reduced from 25 to 20.2 mm, and an inner hole is produced with a diameter of 199.8 mm. With the specific machining energies from Table 8.8 the coarse machining energy accounts to 6.10 MJ. The final fine machining operations reduce the outer diameter to 390 mm, the body width to 20 mm, and opens the inner diameter to 200 mm, resulting in fine machining energy of 1.54 MJ. The CBN segments are then glued to the steel body, but the gluing energy is neglected. Material data and energy data for rough rolling, coarse machining, and fine machining are taken from a database [GRAN12].