po

1. School of Material
EBT 536
CASE STUDY:
MATERIAL SELECTION FOR COMPACT DISC
Lecturer: Dr. AZLINE
Student Name: Asma Faraj Amgawer Haiba
Matric No. 1831622626
SEP. 2018

2. WHAT IS THE COMPACT DISC
.
hole in the middle is 15 mm in diameter.
A CD usually weighs between 15 - 20 grams
120 mm out diameter
1.2mm thick

3. WHY COMPACT DISC
A portable
storage
medium
can be used to record,
store and play
back audio, video and
other data
in digital form
A standard CD
can store up to 74
minutes of data.
650 megabytes (MB)
to 700 MB of data.

4. WHAT IS THE COMPONENT OF COMACT DISC
 Compact discs are made from a disc of plastic coated with a much thinner aluminum layer.
 Aluminum layer is protected by a film of lacquer, which can be printed with a label.
 Injection molding is used to manufacture compact discs.

5. MATERIAL SELECTION
CDs should have the following properties
• Easy to fabricate
• Does not break easily if drop
• Cheap (reasonable price),
• Dimensional stability
• Flexibility,
• Rigid

6. EVALUATION OF THE CANDIDATES
AND MATERIAL SELECTION.
Property
Polystyrene
(PS)
Polycarbonate
(PC)
Polyvinylchloride(
PVC)
Easy to fabricate +++ ++ ++
Izod impact (KJ/m2) 2 -5 20 – 35 2 - 4
Tensile strength (MPa) 35.9 ‐ 51.7 55 - 75 52 - 54
Young modulus (GPa) 2.28 - 3.34 2.21 - 2.44 2.14 - 4.14
Cost ($/kg) 1.3 - 1.6 3.8 - 4.3 1 - 1.2
Density (g/cm3) 1.04 - 1.05 1.2 - 1.22 1.3 – 1.45
Linear thermal expansion coefficient
(α) (1/K)
8*10-5 6.5*10-5 5*10-5
Fracture toughness (MPa.m1/2) 0.7 - 1.1 2.1 - 4.6 1.46 - 5.12

7. CONCLUSION
Polycarbonate (PC)
Is the best