Skip to content

Slide 003: Job Setup, File Loading & Cut Execution

Slide Visual

Job Setup, File Loading & Cut Execution

Slide Overview

This slide covers the complete procedure for setting up and executing a CNC plasma cutting job, from loading the cut file to the first pierce. Students will learn the standard operating procedure that ensures consistent, safe, and accurate cuts.

Instruction Notes

File Preparation Pipeline

  1. Design: Create or import 2D profile in CAD (DXF/SVG is the standard exchange format)
  2. CAM/Nesting: Import into plasma CAM software (SheetCAM, Fusion 360, ProNest, or built-in controller nesting)
  3. Assign cut profiles and kerf compensation
  4. Set cut direction (CW for outside, CCW for inside)
  5. Assign lead-ins (typically small arc lead-in, 0.125"–0.25" radius, placed on scrap side)
  6. Sequence operations: holes first, then exterior profiles
  7. Post-process: Generate G-code with plasma-specific codes (M3 = torch on, M5 = torch off, THC commands)
  8. Transfer: Load G-code to the CNC controller via USB, network, or direct connection

Material Setup Procedure

Step 1: Position Material - Place metal sheet on the slat table, ensuring it spans multiple slats for support - Do NOT let the material hang off the edge of the table - For thin material (<16 gauge): use weights or clamps to flatten warps

Step 2: Work Clamp - Attach the work clamp directly to the workpiece (not the table frame) - Clean the contact point to bare metal if painted or rusty - Position the clamp where it will not interfere with torch travel - Route the ground cable away from the torch path to prevent snags

Step 3: Water Table - Fill to the correct level: just touching the bottom of the workpiece OR ΒΌ" below the bottom surface - Too high: water interferes with the arc, causes spatter, may short the THC - Too low: reduced fume capture, more noise, less cooling

Step 4: Set Machine Origin - Jog the torch to the desired starting corner of the material - Set X=0, Y=0 in the controller - Z-zero is handled automatically by the IHS (Initial Height Sense) before each pierce

Cut Execution

Pre-Cut Checks (MANDATORY)

[ ] Air pressure: 65-75 PSI, moisture indicator green
[ ] Consumables: electrode pit <0.040", nozzle orifice round
[ ] THC voltage: set for material/amperage combination
[ ] Water table: correct level
[ ] Work clamp: solid contact on workpiece
[ ] File preview: toolpath within material boundaries
[ ] PPE: all personnel equipped
[ ] Fire extinguisher: within 15 feet
[ ] Welding screens: deployed around cutting area

Starting the Cut 1. Put on welding helmet and verify shade (8-12 depending on amperage) 2. Verify all personnel are behind screens or wearing appropriate PPE 3. Press "cycle start" or equivalent β€” the machine will: - Move to the first pierce point - Lower the torch (IHS probes the surface) - Retract to pierce height (1.5-2Γ— cut height) - Start the arc (pilot arc β†’ transferred arc) - Wait for pierce delay - Begin cutting at programmed speed and lower to cut height 4. Monitor the first pierce and initial cut β€” verify arc transfers and cut quality is acceptable 5. Remain at the controls throughout the entire cutting operation

During the Cut β€” Monitoring

  • Listen for consistent arc sound β€” changes indicate problems
  • Watch for excessive sparks below the table β€” may indicate water level too low
  • Monitor THC behavior β€” if the torch is hunting (oscillating up/down), the THC may need tuning
  • Be ready for E-stop if anything goes wrong

Key Talking Points

  1. File preparation is half the job β€” a well-prepared file prevents most cutting errors
  2. The work clamp connection is a safety-critical setup step β€” never skip it
  3. Water table level affects fume capture, noise, and cut quality β€” check every job
  4. The IHS system eliminates manual Z-zeroing but must be verified on the first pierce
  5. Never start a cut without completing the pre-cut checklist

Learning Objectives (Concept Check)

  • [ ] Describe the complete file preparation pipeline from DXF to G-code
  • [ ] Execute the material setup procedure including work clamp, water table, and origin setting
  • [ ] Perform the pre-cut checklist and initiate a CNC plasma cutting job

Last Updated: 2026-03-19