Activity 001: CNC Plasma Table Setup & Consumable Inspection¶
Activity ID: U5M3-ACT-001 Duration: 40 minutes Objective: Students will perform a complete CNC plasma table setup including consumable inspection, air system verification, water table check, and work clamp placement. Group Size: 2-3 students
Overview¶
Students will walk through the complete machine setup procedure on the CNC plasma table, inspecting every component and verifying readiness for cutting. This is a supervised hands-on activity that builds competency with the physical setup before any cutting occurs.
Materials & Equipment Needed¶
- CNC plasma table (powered off initially)
- Plasma power supply
- Set of new consumables (electrode, nozzle, swirl ring, shield cup) for comparison
- Set of worn consumables showing end-of-life indicators
- Electrode pit depth gauge or calipers with depth rod
- Magnifying loupe (10×)
- 12 gauge mild steel plate (12" × 12") for setup practice
- Work clamp
- Setup checklist worksheet
- PPE: Safety glasses, leather gloves
Instructions & Procedure¶
Phase 1: Air System Verification (8 minutes) 1. Check compressor oil level and tank pressure 2. Open the drain valve on the compressor tank — drain any accumulated water 3. Check the water separator — drain if water is present 4. Check the coalescing filter — replace if discolored or indicator shows saturated 5. Check the desiccant dryer indicator — green = dry, pink/blue = saturated 6. With the plasma cutter powered off, press the air check button (or momentarily trigger the torch) to verify air flows and read pressure on the regulator 7. Adjust pressure to 65-70 PSI 8. Record all findings on the worksheet
Phase 2: Torch & Consumable Inspection (12 minutes) 1. Remove the shield cup from the torch 2. Remove the nozzle — inspect the orifice: - Use the loupe to check if the orifice is round or oblong - Compare to a new nozzle side-by-side - Record condition: Good / Worn / Replace 3. Remove the electrode — inspect the hafnium insert: - Measure the pit depth with calipers (depth rod) or pit depth gauge - Record depth: ___ inches (replace threshold: 0.040"–0.080") - Compare to new and worn reference electrodes 4. Inspect the swirl ring for cracks, discoloration, or clogged passages 5. Inspect the shield cup for spatter buildup — clean with a wire brush if needed 6. Reassemble the torch in correct order: electrode → swirl ring → nozzle → shield cup 7. Verify the assembly is snug but not over-tightened
Phase 3: Table & Material Setup (12 minutes) 1. Inspect the slats — note any severely damaged slats that need replacement 2. Check the water table level — adjust to the correct height 3. Place the practice steel plate on the slats 4. Position the material so it spans at least 3 slats 5. Attach the work clamp to the steel plate: - Clean the contact area with a wire brush - Attach clamp firmly — wiggle test (should not move) - Route the cable away from the anticipated torch path 6. Set machine origin: power on the controller, jog to the front-left corner of the material, set X=0, Y=0
Phase 4: Pre-Cut Verification (8 minutes) 1. Load a test G-code file (or simulate loading) 2. Run through the complete pre-cut checklist: - Air pressure reading: _____ PSI (target: 65-75) - Consumable condition: Pass / Fail - Water table level: Correct / Adjust - Work clamp: Solid / Needs attention - THC voltage: Set for 40A steel - File preview: Within material boundaries - Fire extinguisher: Located and accessible 3. Present findings to the instructor — report any items that required correction 4. Instructor verifies setup quality
Discussion Points¶
- How can you tell the difference between a consumable that is worn but usable vs. one that needs replacement?
- What happens if you cut with a worn nozzle? Worn electrode? Both worn?
- Why is the work clamp placement on the workpiece itself (not the table) so important?
- How would you know if the air quality is degrading consumable life faster than normal?
Expected Outcomes¶
- Students can independently set up a CNC plasma table for cutting
- Students can inspect and evaluate consumable condition
- Students understand the complete pre-cut checklist and its importance
Assessment Rubric¶
| Criteria | Excellent (4) | Proficient (3) | Developing (2) | Beginning (1) |
|---|---|---|---|---|
| Air System Verification | All checks completed, issues identified and addressed | All checks completed | Most checks completed | Skipped critical checks |
| Consumable Inspection | Accurately assesses wear, correct assembly | Identifies worn consumables, correct assembly | Partial inspection, minor assembly errors | Cannot assess consumables |
| Table/Material Setup | Complete setup with all best practices | Good setup with minor improvements needed | Setup completed with significant assistance | Cannot complete setup |
| Pre-Cut Checklist | All items verified with documented readings | Most items verified | Incomplete checklist | Does not understand checklist |
Safety Considerations¶
- Machine must be powered off during consumable inspection and torch disassembly
- Wear leather gloves when handling the torch and consumables — edges can be sharp
- Never look directly at the plasma arc — welding helmet required before any arc is struck
- The torch retains heat after cutting — verify it is cool before disassembly
- Work clamp cable is heavy — avoid back strain when routing
Last Updated: 2026-03-19