Activity 002: Material Test Cut Analysis Lab

Activity ID: U3M2-ACT-002 Duration: 45 minutes Objective: Students will analyze pre-cut test samples from multiple materials and evaluate cut quality, engraving depth, kerf width, and edge characteristics to build material-specific knowledge. Group Size: 2-3 students per analysis station Materials Cost: ~$10-15 (pre-cut samples prepared by instructor, reusable)

Overview

The instructor prepares a set of pre-cut material samples (cut at optimal settings before class) from 5-6 different materials. Students examine each sample's cut quality, measure kerf width, evaluate engraving depth and contrast, and compile a material properties database based on their observations.

Materials & Equipment Needed

• Pre-cut sample set (prepared by instructor, 5-6 materials, each with cut lines and engraved squares):
• 3mm cast acrylic (cut + engrave)
• 3mm birch plywood (cut + engrave)
• 3mm MDF (cut + engrave)
• 2mm leather (cut + engrave)
• 2mm cardboard (cut + engrave)
• Optional: cork, felt, or glass (engrave only)
• Digital calipers (0.01mm resolution)
• Magnifying glass or digital microscope
• Ruler
• Material analysis worksheet
• Camera/phone for documentation

Instructions & Procedure

Phase 1: Cut Edge Analysis (15 min) 1. For each material sample, examine the CUT edge under magnification and record: - Edge quality: Rate 1-5 (1=rough/charred, 5=clean/polished) - Kerf width: Measure at top and bottom of cut with calipers - Taper: Calculate the difference between top and bottom kerf (top is always wider) - Heat-affected zone: Measure the visible discoloration width around the cut - Edge color: Describe (polished clear, brown, black, sealed, etc.) - Edge feel: Smooth, rough, or sticky when touched (with gloves for leather) 2. Rank the materials from best to worst cut edge quality 3. Photograph each cut edge under magnification

Phase 2: Engraving Analysis (15 min) 4. For each material's engraved square, evaluate: - Contrast: Rate 1-5 (1=barely visible, 5=high contrast) - Depth: Measure with calipers or depth gauge if available - Surface quality: Rate 1-5 (1=rough/pitted, 5=smooth/uniform) - Detail resolution: Examine fine features — are small text and lines clearly defined? - Residue: Is there smoke residue or ash in the engraved area? 5. Rank the materials from best to worst engraving quality 6. Note which materials would be best for: text engraving, photo engraving, deep engraving (stamps)

Phase 3: Material Properties Database (10 min) 7. Compile your observations into a material properties table:

Material	Kerf (mm)	HAZ (mm)	Cut Edge Quality	Engrave Contrast	Best Use
Cast Acrylic	___	___	___/5	___/5
Plywood	___	___	___/5	___/5
(etc.)

1. For each material, write one recommendation: "Best for " and one limitation: "Not suitable for "
2. Compare your data with other groups — are measurements consistent?

Phase 4: Application Matching (5 min) 10. Match each material to its ideal laser application: - Gift shop product (engraved coasters, ornaments) - Precision mechanical parts (gears, brackets) - Signage (engraved text with high visibility) - Prototyping (quick test of part geometry) - Fabric/leather goods (wallets, patches)

Discussion Points

• Why does cast acrylic produce polished edges while wood produces charred edges?
• Which material had the widest kerf? The narrowest? What does this mean for precision parts?
• If you needed to laser-cut gears that mesh together, which material would you choose and why?
• How would you modify settings to reduce the heat-affected zone on plywood?

Expected Outcomes

• Cast acrylic should show the narrowest kerf (0.15-0.20mm) and cleanest edges
• Plywood should show the widest HAZ (0.2-0.5mm) and most charring
• MDF should show the most consistent/uniform results (homogeneous material)
• Leather should show sealed edges with moderate charring
• Students should correctly match materials to appropriate applications

Assessment Rubric

Criterion	Excellent (5)	Proficient (3)	Needs Improvement (1)
Measurement Accuracy	All kerf and HAZ measurements within 0.05mm of group consensus	Most measurements accurate with minor deviations	Significant measurement errors or missing data
Quality Ratings	Ratings consistent with material properties and well-justified	Ratings present but justification weak	Ratings appear arbitrary
Database Completeness	All fields filled, recommendations specific and useful	Most fields filled, generic recommendations	Incomplete database
Application Matching	All applications correctly matched with technical reasoning	Most correct with basic reasoning	Multiple incorrect matches

Safety Considerations

• All samples are pre-cut — no laser operation during this activity
• Some cut edges (especially acrylic) may be sharp — handle carefully
• Charred wood edges may leave soot on fingers — wash hands after handling
• Do not inhale close to freshly cut materials — some may still off-gas slightly
• Wear safety glasses when examining samples under magnification (eye strain)

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Last Updated: 2026-03-19