Machinists & CNC Operators
Lathes, mills, drill presses and CNC machines remove metal with spinning tools and parts. Entanglement, flying chips and coolant exposure are the main hazards.
- Manufacturing
Top hazards
- Entanglement of sleeves, gloves, hair or jewelry in rotating chucks and spindles
- Flying chips and broken tools
- Sharp chips and burrs
- Metalworking fluid (coolant) mists and skin contact: dermatitis and breathing problems
- Chuck keys left in lathes
- Heavy parts and fixtures
Key practices
- No gloves, loose sleeves, jewelry or loose hair near rotating parts.
- Keep CNC doors and machine guards closed and interlocks working.
- Wear safety glasses; use chip shields.
- Remove chuck keys immediately; use self-ejecting keys.
- Use brushes or hooks, never hands, to clear chips, and only with the machine stopped.
- Maintain coolant, use mist collectors, and wash skin.
- Lock out for tool changes and maintenance when required.
Machine by machine
| Machine | Key hazard | Key control |
|---|---|---|
| Lathe | Entanglement in the chuck or workpiece; chuck key thrown | No gloves or loose clothing; remove the key; chuck guard |
| Milling machine | Cutter contact; flying chips | Guards, clamps on work, stop the spindle before measuring |
| Drill press | Work spinning with the bit; hair and sleeve entanglement | Clamp the work; never hold it by hand |
| CNC machining center | Unexpected movement; crashing tools; ejected parts | Doors closed and interlocked; verify programs; stay out during cycles |
| Surface and bench grinders | Wheel breakage | Ring test, rated wheel speed, tool rest gaps. See Bench Grinders |
CNC setup and prove-out
- Run new programs with single block and reduced rapid override until you’re sure of the tool path.
- Check work offsets and tool lengths; a crash can throw parts and broken tooling.
- Never reach into the machine during a cycle or bypass door interlocks.
Metalworking fluids
Coolant can grow bacteria and fungi, and mists can cause asthma, bronchitis and skin rashes. Keep coolant at the right concentration, skim tramp oil, use mist collectors, wear gloves when handling parts (but not near rotating tools), and wash skin before eating.
Start-of-shift checklist
- Guards and interlocks working
- Safety glasses on; no gloves, jewelry or loose clothing near rotating parts
- Chuck key and tools removed from the machine
- Work securely clamped
- Chip brushes and hooks at hand
- Coolant and mist collector working
- Floor clear of chips and oil
Standards & references
- 29 CFR 1910.212: Machine guarding
- OSHA: Metalworking fluids
Last updated: