1. PHYSICAL PROPERTIES OF MATERIALS
Properties that define the behavior of materials in response to physical forces other than mechanical
Volumetric
Thermal
Electrical
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

2. Volumetric and Melting Properties
Properties related to the volume of solids and how the properties are affected by temperature
Includes:
Density
Thermal expansion
Melting point
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

3. Density and Specific Gravity Defined
Density = weight per unit volume
Typical units are g/cm3 (lb/in3)
Specific gravity = density of a material relative to density of water and is a ratio with no units
Why is density important?
Strength – to – weight ratios
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

4. Coefficient of Thermal Expansion
Change in length per degree of temperature
1/C or 1/F
L2 ‑ L1 = L1 (T2 ‑ T1)
 = coefficient of thermal expansion
L1 and L2 are lengths
corresponding to
T1 and T2 temperatures
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

5. Volumetric Properties
Material
Density, 
Coeffcient of Thermal Expansion, a
Melting Point, Tm
g/cm3
lb/in3
ºC-1 x 10-6
ºF-1 x 10-6 ºC ºF
Aluminum
2.70
0.098 24
13.3
660
1220
Copper
8.97
0.324 17
9.4
1083
1981
Steel
7.87
0.284 12
6.7
alloy
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

6. Melting Characteristics for Elements
Melting point Tm of a pure element
transforms from solid to liquid state
Reverse transformation
freezing point
Heat of fusion
heat energy required at Tm
transformation from solid to liquid
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

7. Melting of Metal Alloys
Alloys do not have a single melting point
Solidus
Liquidus
Between the two temperatures, the alloy is a mixture of solid and molten metals
Exception: eutectic alloys melt (and freeze) at a single temperature
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

8. Melting of Alloys: Solidus and Liquidus
Figure 6.3 Phase diagram for the tin‑lead alloy system.
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

9. Electrical Properties
Ohm's law: I =
I = current, A units
E = voltage, V units
R = electrical resistance,  units
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

10. Electrical Resistance
Resistance in a uniform section of material (e.g., a wire)
L=length
A=cross‑sectional
resistivity of the material r
where resistivity r has units of ‑m (‑in)
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

11. Resistivity Properties
Material
Resistivity
Ω-m
Ω-in
Aluminum
2.8 x 10-8
1.1 x 10-6
Copper
1.7 x 10-8
0.67 x 10-6
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

12. In-class example
The starting diameter of a steel shaft is mm. This shaft is to be inserted into a hole in an expansion fit assembly operation. To be readily inserted, the shaft must be reduced in diameter by cooling. Determine the temperature to which the shaft must be reduced from room temperature (20C) in order to reduce its diameter to mm. Refer to Table 4.1.
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

13. SME Video
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing

14. ASSIGNMENT – STUDENT MUST SHOW SOLUTION TO PROFESSOR DURING LAB PERIOD
A bridge built with steel girders is 500 m in length for -35°C temperatures and 50 m in width. From historical records it is estimated that the maximum temperature in the region will be 38°C. What is the expanded length of the steel girder?
John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing