Coolant Strategy = Surface Finish (and Tool Life)

Treat coolant like a key process variable—not a utility. Pressure, flow, direction, filtration, and thermal regime directly control Ra and tool life.

Make these four decisions

• Pressure & flow: set to cutter spec and verify under load; drifting pressure = drifting Ra.
• Direction: hit the cutting zone, not just “somewhere nearby.”
• Filtration: monitor differential pressure; fines recut and ruin finish.
• Thermal regime: dry/MQL for hardened steel/CBN; if wet, don’t toggle—avoid shock.

Simple weekly habits

• Log pressure/flow with part quality; alarm on deviation.
• Inspect chip form; stringers mean wrong breaker or poor aim.
• Clean nozzles; verify through-tool passages.

Payoff

Ra stability, longer tool life, lower CPC.
Sigma’s coolant audits give you a baseline chart linking pressure/flow to finish and life—so you stop fiddling and start controlling.