... sealing is more efficient, and more suitable for drilling at high rotary speed and high tem-perature working condition.3. ... etc. Recommended Bit type: 437, Drilling weight: 0.35~0.90 KN/mm, Rotary speed, 240~60 r/m.2, ... etc. Recommended Bit type: 517, Drilling weight:0.35~1.05 KN/mm, Rotary speed, 220~60 r/m.3 ... etc. Recommended Bit type: 537, Drilling weight 0.35~1.05 KN/mm, Rotary speed, 200~40 r/m. F ...