Coolant-Quality

The coolant filtration system is the first thing I check when a deep hole drilling operation starts producing inconsistent results. Dirty coolant causes more tool failures, surface finish problems, and bore diameter drift than almost any other single factor. I have seen a shop cut tool life in half simply by letting their filtration maintenance slip by two weeks. Why Filtration Matters More in Deep Hole Drilling Deep hole drilling generates fine chips that stay suspended in the coolant much longer than the chips from turning or milling. A gun drilling operation produces chips that are typically 0.01 to 0.05 mm thick and 1 to 5 mm long. These chips pass through the drill head coolant holes at high velocity. If chips recirculate through the system, they erode seals, clog coolant passages, and scratch bore surfaces. ...

I use 20-micron filtration for gun drilling and 50-micron for BTA. I cut my tooling costs by 35% within six months of upgrading from 50-micron to 20-micron on my gun drilling line. That is not a theoretical number — I measured it against the previous year’s spending. Coolant filtration matters more in deep hole drilling than in any other machining process I know. The cutting zone is at the bottom of a deep, narrow hole. Chips have to travel the full length of the bore to escape. If unfiltered coolant recirculates chips back into the cut, they damage the cutting edge and score the bore surface. Here is what I have learned about choosing the right micron rating. ...