Coolant (cutting fluid) does three jobs: it carries away heat, lubricates the cut, and flushes chips. Choosing it means matching the delivery method and fluid type to the material and operation.
Delivery methods
- Flood — a steady stream; the default for most cutting, with great heat removal and chip flushing.
- Mist — a fine spray; lighter cooling, less mess, useful where flood isn’t practical.
- Air blast — no liquid, just chip clearing; common in aluminum and where dry cutting is preferred.
Fluid types
| Type | Notes |
|---|---|
| Soluble (emulsion) oil | Water + oil; good all-round cooling + lubrication |
| Synthetic | Water-based, no oil; great cooling, clean |
| Semi-synthetic | Middle ground |
| Straight oil | Best lubrication, less cooling; heavy-duty/threading |
Heat-dominated jobs (high speed, steel, stainless, titanium) want strong cooling — flood with a synthetic or soluble oil. Friction-dominated jobs (tapping, threading) want lubrication — straight or semi-synthetic oils. Keep water-based coolant at the right concentration; too weak invites rust and bacteria.
Frequently asked questions
Flood or mist? Flood for most cutting; mist where flood is impractical.
Best coolant for titanium? Strong, generous cooling — flood (or high-pressure) coolant.
Can I machine aluminum dry? Often with air blast to clear chips; light cuts especially.
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