1581 Application Operating Condition Instructions Operating Condition Instructions The entry surface is slanted – Level the slope through spot facing before machining The entry surface is welded – Level it through spot facing before machining The outlet is slanted – Reduce the feed rate by 50% at the outlet Stacked plates – Allowed in principle – The workpiece shall be properly clamped – No excessive gap is allowed between the plates The entry surface is arc – Drilling at the centre at reduced feed rate is allowed – Spot facing is required if the entry point is not at the centre of the arc Cavities – Not allowed Through hole – Reduce the feed rate by 50% during continuous cutting Step on the entry surface – Not allowed (the entry point must be on a horizontal plane) Criteria for drill replacement Power limit Wear limit Poor surface roughness Hole diameter change Drastic increase of vibration noise P 1 P × 1.25 2 1 New drill 2 A worn drill has a power 25% higher than that of a new drill Ra D ∅>D+0.15mm ∅<D-0.03mm EXCHANGEABLE DRILLS 11 Index 10 9 OIL 8 7 6 5 4 3 2 1
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