... more efficient, and more suitable for drilling at high rotary speed and high tem-perature working condition.3. New materl ... 437, Drilling weight: 0.35~0.90 KN/mm, Rotary speed, 240~60 r/m.2, Soft with low comprssive strength ... 517, Drilling weight:0.35~1.05 KN/mm, Rotary speed, 220~60 r/m.3, Medium soft with hard ... 537, Drilling weight 0.35~1.05 KN/mm, Rotary speed, 200~40 r/m. F/FC series tricone rock ...