What coolants and cutting oils do to the luminaire
Inside the work area of a machine tool the luminaire is permanently wetted by coolant aerosol and also directly hit during cleaning. Three load modes must be distinguished:
- Water-mixed coolant emulsions (typical pH 9–10) — main load in high-volume CNC operation. They attack aluminium natural surfaces and standard seals long term.
- Neat cutting oils (mineral or synthetic) — chemically less aggressive but creep through gaps and wet internal surfaces.
- Cleaning and flushing chemistry — alkaline cleaners, solvents at tool change.
Standard industrial luminaires without dedicated material choice rarely survive this load for more than a few months without clouding or corrosion.
Material choice: housing, optic and seal
Robust solutions combine three material layers:
- Housing: aluminium with hard-anodised finish (coating ≥ 20 µm) or stainless steel 1.4404. Pure powder coating is insufficient under permanent emulsion contact.
- Light cover: borosilicate glass or polycarbonate with splinter protection. PMMA (acrylic) clouds visibly under aerosol load.
- Seals: FKM (Viton) or peroxide-cured EPDM — resistant to water-mixed emulsions and hot cleaning. Standard NBR/Buna is not sufficient.
The joints of these material layers must be fully sealed. Screw connections without sealing rings are weak points in aerosol environments.
IP rating, cleanability and practice testing
Two IP values are relevant for machine lighting in the work area:
- IP67 — dust-tight and protected against temporary immersion. Minimum for machine integration.
- IP69K (ISO 20653) — additionally protected against high-pressure and hot-water-jet cleaning. Recommendation for intensively cleaned machines.
Reputable manufacturers state the resistance against typical cutting oils and coolant emulsions explicitly in a chemicals list. When in doubt, a material sample should be tested ≥ 72 h with the actual coolant before placing a major order — aerosol load is harder to predict from a datasheet than the IP rating.