Deep Hole Drilling Parameters

Cutting speed, feed rate, and coolant parameters are the three primary variables in deep hole drilling. Unlike conventional drilling, these three must be carefully coordinated — coolant must deliver adequate pressure (50–200 bar for gun drilling, 20–60 bar for BTA, 15–40 bar for ejector) and volume to the cutting edge while flushing chips effectively; speed and feed must be balanced for tool life and hole quality. Recent research shows coolant pressure optimization alone can double tool life. Depth ratio adjustments are critical as hole depth increases, requiring progressive parameter derating at high L/D ratios.