Five grinding wheels were employed for easy-to-grind bearing steel AISI 52100. The wheels are listed in Table 19.4. The medium-speed wheels were larger than the high-speed wheels as indicated in Table 19.3.
A two-level experimental arrangement for eight factors based on an L1628 array was used to determine the best conditions using high-speed CBN. Other trials were designed to determine best conditions for conventional speeds. Typical values of the parameters are given in Figure 19.29. Further details are available from Ebbrell [2003].
For best results, the following dressing and grinding conditions were selected from the basic trials and confirmed by confirmation trials for AISI 52100: •
Grinding Wheels and Machines for Grinding AISI 52100
Abrasive Wheel Wheel Speed
Type Specification (m/s)
Vitrified Al2O3 A46 K5V 45
Vitrified Al2O3 A80 J6V 45
Vitrified SG A60 J8V 45
Vitrified CBN B91 (Medium speed) 45
Vitrified CBN B91 (High speed) 60-120
• Conventional-speed CBN wheel. The conventional-speed B91 CBN wheel was up — dressed with a rotary disk dresser. The wheel was dressed at a speed, vr = -12.6 m/s, ad =
2 |jm, vd = 3.9 mm/s, and nd = 2. Grinding conditions were vs = 45 m/s, vw = 26 m/min, tso = 10 s, and Q’w = 4 mm3/mm/s.
• High-speed B91 CBN wheel. The high-speed B91 CBN wheel was dressed at vr = -42 m/s, ad = 2 |jm, vd = 1.7 mm/s, and nd = 2. Grinding conditions were vs = 120 m/s, vw = 26 m/min, tso = 2 s, and Q’w = 20 mm3/mm/s.