1. Final Exam Review

2. Material-Process-Geometry Relationships
Function
Role of Prod Engr
Material
Geometry
Role of Mfg Engr
Process

3. Materials in Manufacturing
Most engineering materials can be classified into one of four basic categories:
Metals
Ceramics
Polymers
Composites

4. Processing Operations
Three categories of processing operations:
Shaping operations - alter the geometry of the starting work material
Property‑enhancing operations - improve physical properties of the material without changing its shape
Surface processing operations - clean, treat, coat, or deposit material onto the exterior surface of the work

5. Shaping – Four Main Categories
Solidification Processes - starting material is a heated liquid that solidifies to form part geometry
Deformation Processes - starting material is a ductile solid that is deformed
Material Removal Processes - starting material is a ductile/brittle solid, from which material is removed
Assembly Processes - two or more separate parts are joined to form a new entity

6. Comparing Processes

7. Stress-Strain Relationships
Figure 3.3 Typical engineering stress‑strain plot in a tensile test of a metal.

8. True Stress-Strain Curve
Figure 3.4 ‑ True stress‑strain curve for the previous engineering stress‑strain plot in Figure 3.3.

9. Strain Hardening
Figure 3.5 True stress‑strain curve plotted on log‑log scale.

10. Recrystallization and Grain Growth
Scanning electron micrograph taken using backscattered electrons, of a partly recrystallized Al-Zr alloy. The large defect-free recrystallized grains can be seen consuming the deformed cellular microstructure. µm

11. Phase Dispersion – speed of quenching

12. Allotropic Transformation and Tempering
Austenizing
Quenching
Figure 6.4 Phase diagram for iron‑carbon system, up to about 6% carbon.
Tempered Martensite 12

13. Precipitation Hardening - Al 6022 (Mg-Si)
Figure Precipitation hardening: (a) phase diagram of an alloy system consisting of metals A and B that can be precipitation hardened; and (b) heat treatment: (1) solution treatment, (2) quenching, and (3) precipitation treatment. 13

14. Machining Relationships
Machine Tool
Workholding Tool
Cutting Tool
Workpiece

15. Effect of Higher Shear Plane Angle
Higher shear plane angle means smaller shear plane which means lower shear force, cutting forces, power, and temperature
Figure Effect of shear plane angle  : (a) higher  with a resulting lower shear plane area; (b) smaller  with a corresponding larger shear plane area. Note that the rake angle is larger in (a), which tends to increase shear angle according to the Merchant equation 15

16. Turning Parameters Illustrated

17. Machining Calculations: Turning
Spindle Speed - N (rpm)
v = cutting speed
Do = outer diameter
Feed Rate - fr (mm/min -or- in/min)
f = feed per rev
Depth of Cut - d (mm -or- in)
Df = final diameter
Machining Time - Tm (min)
L = length of cut
Mat’l Removal Rate - MRR (mm3/min -or- in3/min)

18. Unit Power in Machining
Useful to convert power into power per unit volume rate of metal cut
Called the unit power, Pu or unit horsepower, HPu or
Tool sharpness is taken into account multiply by 1.00 – 1.25
Feed is taken into account by multiplying by factor in Figure 21.14
where MRR = material removal rate

19. What if feed changes?
As feed decreases, we are cutting material that is progressively harder due to strain hardening from prior pass.

20. Unit Horsepower
The significance of HPu is that it can be used: 1) to determine the size of the machine tool required to perform a particular cutting operation; and 2) the size of the cutting force on the workholding and cutting tools.
HPu ~ hp/in3/min
Cf ~ correction factor
MRR ~ in3/min
Fc ~ lb
V ~ ft/min
E ~ machine tool efficiency
33,000 ~ conversion between ft-lb & hp

21. Example
In a turning operation on stainless steel with hardness = 200 HB, the cutting speed = 200 m/min, feed = 0.25 mm/rev, and depth of cut = 7.5 mm. How much power will the lathe draw in performing this operation if its mechanical efficiency = 90%.
From Table 21.2, U = 2.8 N-m/mm3 = 2.8 J/mm3
Since feed is 0.25 mm/rev, the correction factor is 1

22. Example: Solution MRR = vfd = (200 m/min)(103 mm/m)(0.25 mm)(7.5 mm)
= 375,000 mm3/min = 6250 mm3/s
Pc = (6250 mm3/s)(2.8 J/mm3)(1.0) = 17,500 J/s
= 17,500 W = 17.5 kW
Accounting for mechanical efficiency, Pg
= 17.5/0.90 = kW

23. Common process attributes:
Casting
Common process attributes:
Flow of Molten Liquid Requires Heating
Heat Transfer of Liquid in Mold Cavity During and After Pouring
Solidification into Component

24. Gating System
Channel through which molten metal flows into cavity from outside of mold
Consists of a downsprue, through which metal enters a runner leading to the main cavity
At top of downsprue, a pouring cup is often used to minimize splash and turbulence as the metal flows into downsprue

25. Pouring Calculations Minimum mold filling time, MFT MFT =V/Q
Q: volumetric flow rate, cm3/s
V: mold cavity volume, cm3

26. Chvorinov's Rule where TST = total solidification time;
V = volume of the casting;
A = surface area of casting;
n = exponent usually taken to have a value = 2; and
Cm is mold constant

27. Amount and Composition
Figure 6.2 Phase diagram for the copper‑nickel alloy system.

28. Shrinkage in Solidification and Cooling
Figure Shrinkage of a cylindrical casting during solidification and cooling: (0) starting level of molten metal immediately after pouring; (1) reduction in level caused by liquid contraction during cooling (dimensional reductions are exaggerated for clarity).

29. Shrinkage in Solidification and Cooling
Figure (2) reduction in height and formation of shrinkage cavity caused by solidification shrinkage; (3) further reduction in height and diameter due to thermal contraction during cooling of solid metal (dimensional reductions are exaggerated for clarity).