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Safety Protocol 001: CNC Cutting Operations — Active Monitoring & Emergency Response

Protocol ID: U4M4-SAFE-001 Context: Safety procedures during active CNC cutting operations, including monitoring requirements, emergency response, and incident-specific protocols Hazard Level: High — Active cutting involves rotating tools, flying debris, noise, dust, and potential for material ejection

Potential Hazards

During Active Cutting

  • Tool breakage and fragment ejection: Broken carbide end mills can send fragments at velocities exceeding 100 MPH. Fragment size and trajectory are unpredictable
  • Material ejection: Workholding failure during cutting launches material at high speed. A 12"×12" piece of ¾" plywood weighs ~2.5 lbs and can cause serious injury
  • Fire: Wood dust, especially from MDF and resinous softwoods, can ignite from friction heat when chip load is too low. Dust collection systems with accumulated fine dust are also a fire risk
  • Entanglement: Loose clothing, hair, jewelry, or rags near the spinning spindle can be caught and pull the operator into the machine
  • Respiratory hazards: MDF dust contains formaldehyde; exotic wood dust (cocobolo, padauk, purpleheart) can cause severe allergic reactions; acrylic/PVC cutting produces toxic fumes

During Post-Processing

  • Sharp edges: All cut materials have sharp edges, particularly aluminum, acrylic, and plywood
  • Tab removal: Chisels and hand saws used for tab removal can slip and cause cuts
  • Pinch points: Removing parts from the CNC bed can involve prying, which creates pinch hazards

Required Precautions & Procedures

Before Starting a Cut

  1. Verify all PPE is worn (see table below)
  2. Clear all unnecessary personnel from the machine area (minimum 3-foot perimeter)
  3. Confirm dust collection is running and all hose connections are secure
  4. Verify fire extinguisher location (must be within 15 feet of the CNC router)
  5. Verify E-stop is accessible and not obstructed
  6. Confirm workholding by physical pull test
  7. Start the program at 50% feed override for the first cut of any new job

During Active Cutting — Operator Monitoring Requirements

  1. Never leave the machine unattended — the operator must be within arm's reach of the E-stop at all times during cutting
  2. Monitor continuously for:
  3. Changes in cutting sound (pitch change, chattering, squealing)
  4. Smoke or burning smell
  5. Material movement or vibration
  6. Chip color changes (blue/purple chips in metal = excessive heat)
  7. Spindle motor strain (reduced RPM under load)
  8. If ANY abnormal condition is observed: reduce feed override immediately. If condition persists or worsens, press E-stop
  9. Do not adjust clamps, clean chips, or touch anything in the cutting area while the machine is running
  10. Keep hands, tools, and measuring instruments at least 12" from the spindle during operation

During Post-Processing

  1. Wait for spindle to reach complete stop before approaching
  2. Wear cut-resistant gloves when handling cut parts (especially metal and acrylic)
  3. Use proper tools for tab removal — never fingers
  4. Deburr all edges before handling parts without gloves

Fire Prevention

  1. Never cut PVC on a CNC router — produces chlorine gas and is a fire/health hazard
  2. Ensure MDF and softwood dust is evacuated — accumulated fine dust is explosive at sufficient concentration
  3. If burning is observed during cutting: increase feed rate immediately via override. If burning continues, E-stop
  4. Check dust collection filters/bags regularly — a full filter reduces airflow and increases fire risk
  5. If a fire starts in the dust collection system: press E-stop, use fire extinguisher on the source, evacuate if fire spreads

Emergency Response

  1. E-stop: Press immediately for any emergency. This is always the correct first action
  2. Tool breakage: E-stop → wait for full stop → inspect operator for injuries → inspect machine → determine cause before resuming
  3. Material ejection: E-stop → check all personnel for injuries → do not approach until all motion stops → secure the area
  4. Fire: E-stop → if small and contained, use fire extinguisher (aim at base of flames) → if spreading, evacuate and call 911 → activate fire alarm
  5. Entanglement: E-stop → do NOT attempt to reverse the machine to free the person → call for emergency assistance → if person is not breathing, begin CPR after they are freed
  6. Respiratory emergency: Move person to fresh air → call 911 if breathing difficulty is severe → provide information about material being cut to emergency responders
  7. Laceration from sharp edges: Apply direct pressure → elevate → seek medical attention for deep cuts → for severe bleeding, apply tourniquet above the wound

PPE Requirements

PPE Item Specification Required When
Safety glasses (ANSI Z87.1) Impact-rated, side shields Always in CNC area
Face shield ANSI Z87.1 rated When cutting metal or brittle materials (acrylic)
Hearing protection NRR 25+ earmuffs or NRR 30+ plugs During all cutting operations
Dust mask — wood N95 minimum Wood, MDF, plywood cutting
Respirator — MDF/exotic wood P100 half-face MDF cutting, exotic hardwoods
Respirator — plastics Organic vapor cartridge (OV/P100) Acrylic, polycarbonate cutting
Closed-toe shoes Composite/steel toe preferred Always in shop
No gloves during operation Entanglement hazard Never wear gloves near running spindle
Cut-resistant gloves ANSI A4+ rating Post-processing, handling cut parts only
Long pants No shorts in shop Always in shop

Last Updated: 2026-03-19