Unit 4: Fabric defects & inspection
Fabric Quality Analysis notes · PTU syllabus (BSTD 401-20)
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Unit summary
Defects lower fabric grade and price, so fabrics are inspected systematically. This unit covers defects in woven fabrics and their causes, and fabric inspection systems.
After this unit you can
- Identify defects in woven fabrics
- Explain causes of defects
- Apply the four-point and ten-point systems
- Describe automated inspection
PTU syllabus topics
Defects in woven fabrics and their causes, fabric inspection systems
4-point system
Defects score 1–4 points by length
Often 40 points per 100 sq yd (buyer-specific)
10-point system
Defects score up to 10 points
Points must not exceed total yards
Common defects
Slubs, broken ends, holes, stains, shade variation
Graded by size and visibility
Topic 1
Defects in woven fabrics
Broken end (warp)
Missing warp thread along the length
Warp breakage not mended
Broken pick (weft)
Missing weft across the width
Weft breakage, stop motion failure
Float
Yarn skips over several threads
Broken end entangled, faulty shedding
Slub and thick place
Thick yarn section
Spinning faults
Starting mark (start-up)
Band of different density
Loom restart without adjustment
Reed mark
Lines along the warp
Damaged reed
Double pick
Two picks in one shed
Weft insertion fault
Holes and cuts
Openings
Sharp parts, temples
Oil and rust stains
Dark marks
Poor maintenance
Barré
Horizontal stripes
Yarn variations in count or dye affinity
Shade variation
Colour differences
Dyeing faults
Topic 2
Fabric inspection systems
Four-point system (ASTM D5430)
Points 1–4 by defect length; maximum 4 points per linear yard
Commonly 40 points or less per 100 square yards
Ten-point system
Points 1–10 by defect length
Total points not exceeding total yards inspected
Graniteville (78) system
Weighted defect classes
Used by some mills
Dallas system
Knits; defects per 100 yards
—
Points per 100 sq yd
Total points × 3,600 ÷ (yards inspected × width in inches)
Example
100 yards of 60-inch fabric with 48 points: 48 × 3,600 ÷ (100 × 60) = 28.8 points — first quality.
- Inspection set-up: inspection table or machine with back and top lighting (about 1,000 lux), 45° viewing angle, measuring counter; inspect 10% of rolls (or as agreed).
- Automated inspection: camera and AI-based systems on looms or inspection machines detect and map defects in real time.
Key terms
- Broken pick
- Missing weft thread
- Float
- Yarn passing over too many threads
- Barré
- Unintended horizontal stripes
- Four-point system
- Defect grading by length up to 4 points
- First quality
- Fabric meeting the agreed defect limit
Quick revision
- Warp-way and weft-way defects and causes.
- Four-point and ten-point systems; calculation; acceptance.
- Inspection conditions; sampling; automated systems.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.Distinguish broken end and broken pick.
- Q2.What causes a starting mark?
- Q3.What is barré?
- Q4.How many points does a 5-inch defect get in the four-point system?
- Q5.State the four-point acceptance limit commonly used.
- Q6.What lighting is needed for inspection?
Long-answer questions
- Q1.Describe common defects in woven fabrics and their causes.
- Q2.Explain the four-point fabric inspection system with a calculation.
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