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Activity 002: Material Identification & Parameter Selection Exercise

Activity ID: U5M2-ACT-002 Duration: 30 minutes Objective: Students will identify unknown metal samples and select appropriate plasma cutting parameters for each, building practical material identification skills. Group Size: 2-3 students

Overview

Students receive labeled and unlabeled metal samples and must identify each material using visual inspection, spark testing, and magnet testing. For each identified material, they will then specify complete plasma cutting parameters. This builds the critical skill of material verification before cutting.

Materials & Equipment Needed

  • 6 metal samples (2" × 4" pieces), labeled A through F:
  • A: Mild steel (magnetic, dark mill scale)
  • B: Stainless steel 304 (slightly magnetic, bright surface)
  • C: Aluminum 6061 (non-magnetic, light weight)
  • D: Galvanized steel (magnetic, spangled zinc surface)
  • E: Copper sheet (non-magnetic, distinctive color/weight)
  • F: Brass (non-magnetic, yellow color)
  • Magnet (strong neodymium preferred)
  • Bench grinder for spark testing (instructor-supervised)
  • Scale (to weigh samples)
  • Parameter reference chart (U5M1-MAT-001)
  • Material identification worksheet
  • PPE: Safety glasses, leather gloves for handling

Instructions & Procedure

Phase 1: Material Identification (12 minutes) For each sample (A through F), perform the following tests and record results:

  1. Visual inspection: Note color, surface finish, weight (heavy/light), and any coatings
  2. Magnet test: Record magnetic (strong/weak) or non-magnetic
  3. Weight comparison: Hold two samples of similar size and compare weight
  4. Spark test (instructor-supervised, at bench grinder): Briefly touch the sample to the grinding wheel and observe spark characteristics:
  5. Mild steel: Long, yellow sparks with many forks
  6. Stainless steel: Short, red-orange sparks, few forks
  7. Aluminum: No sparks (but may produce white streaks)

  8. Galvanized steel: Same sparks as mild steel but with tiny white flashes (zinc)

  9. Record your material identification for each sample

Phase 2: Parameter Selection (12 minutes) For each identified material, specify complete plasma cutting parameters assuming you need to cut it at its given thickness:

Parameter Sample A Sample B Sample C Sample D Sample E Sample F
Material ID
Thickness
Amperage
Speed (IPM)
Gas type
Gas pressure (PSI)
Pierce delay (sec)
Special precautions

For Sample D (galvanized) and Sample E (copper), note any special safety requirements.

For Sample F (brass), determine if it is safe to plasma cut in your facility and explain your reasoning.

Phase 3: Group Discussion & Verification (6 minutes) 1. Instructor reveals the actual material of each sample 2. Compare group identifications — discuss any misidentifications 3. Review parameter selections for accuracy 4. Discuss: What are the consequences of misidentifying a material? (Example: cutting stainless steel with parameters for mild steel; cutting galvanized without respiratory protection)

Discussion Points

  • Why is material identification an essential first step before any plasma cutting?
  • What would happen if you cut copper at mild steel parameters?
  • Which of these metals produces the most hazardous fumes? How would you mitigate the risk?
  • In a real makerspace scenario, how would you verify the material if it is not labeled?

Expected Outcomes

  • Students can identify common metals using visual, magnetic, and spark test methods
  • Students can select appropriate plasma cutting parameters for identified materials
  • Students understand the safety implications of material misidentification

Assessment Rubric

Criteria Excellent (4) Proficient (3) Developing (2) Beginning (1)
Material Identification All 6 correctly identified 4-5 correctly identified 3 correctly identified Fewer than 3 correct
Parameter Selection All parameters correct and justified Most parameters correct Some parameters correct Parameters do not match materials
Safety Awareness Identifies all hazardous materials and precautions Identifies most hazards Identifies obvious hazards only Does not consider material-specific hazards
Test Methodology Uses all tests systematically Uses most tests effectively Limited test usage Cannot perform identification tests

Safety Considerations

  • Spark testing must be performed under instructor supervision
  • Wear safety glasses and leather gloves when handling metal samples
  • Metal samples may have sharp edges — handle by flat surfaces
  • Bench grinder requires face shield in addition to safety glasses
  • Do not spark test unknown metals that could be beryllium, magnesium, or titanium (fire/toxic hazard)

Last Updated: 2026-03-19