1. IEEM 215: Manufacturing Processes

2. Introduction and Agenda Materials Properties - helps to determine how to make things with it - helps to determine the processing conditions - helps and constrains process optimization Processes - forming, cutting, non-traditional, joining, surface treatments, electronics components, … Process Planning Process Economics and Optimization Product design and Fabrication CNC programming Process Evaluation and Quality control Outcome(s) 1.0 1.1 2.0 2.1 7.0 3.0 3.1 4.0 6.0, 6.1 5.0, 8.0, 8.1 5.0 9.0

3. A bottle of Watson’s water (~HK$6) Four components (bottle, cap, label, water) - How are each of these manufactured? - What does the equipment cost? Motivation (1)

4. Motivation (2) Approx. 15 components - How do we select the best material for each component? - How are each of these manufactured? Stapler (~HK$ 45) Car: ~ 15,000 parts; Boeing 747 plane: ~6 million parts Intel core 2 duo processor: 65 nm feature size, 291 million transistors

5. Materials Nanomaterials, shape-memory alloys, superconductors, … Ferrous metals: carbon-, alloy-, stainless-, tool-and-die steels Non-ferrous metals: aluminum, magnesium, copper, nickel, titanium, superalloys, refractory metals, beryllium, zirconium, low-melting alloys, gold, silver, platinum, … Plastics: thermoplastics (acrylic, nylon, polyethylene, ABS,…) thermosets (epoxies, Polymides, Phenolics, …) elastomers (rubbers, silicones, polyurethanes, …) Ceramics, Glasses, Graphite, Diamond, Cubic Boron Nitride Composites: reinforced plastics, metal-, ceramic matrix composites

6. Properties of materials Mechanical properties of materials Strength, Toughness, Hardness, Ductility, Elasticity, Fatigue and Creep Chemical properties Oxidation, Corrosion, Flammability, Toxicity, … Physical properties Density, Specific heat, Melting and boiling point, Thermal expansion and conductivity, Electrical and magnetic properties

7. Mechanical properties: Stress analysis Why do we need stress/strain (not just force, elongation) ? Tension Compression Shear F1 F2 F3 xx  xy yy zz  xz  zx  zy  yx  yz Stresses in an infinitesimal element of a beam Tensile, compressive and shear stresses stress =  = Force/Area

8. xx  xy  yx xx yy yy  xy yy  yx  xy xx    x Stress Analysis: Principal directions in 2D case - principal directions are orthogonal to each other - 0 shear stress along PDs

9. xx  xy  yx xx yy yy  xy yy  yx  xy xx    x Stress Analysis: Principal shear stress in 2D case

10. Failure in Tension, Young’s modulus and Tensile strength Engineering stress =  = P/A o Engineering strain =  e = (L – L o )/L o =  /L o

11. Failure in Tension, Young’s modulus and Tensile strength.. Original Final Necking Fracture

12. Failure in Tension, Young’s modulus and Tensile strength… In the linear elastic range : Hooke’s law:  = E e or, E =  /e E: Young’s modulus

13. Elastic recovery after plastic deformation

14. True Stress, True Strain, and Toughness Engg stress and strain are “gross” measures:  = F/A =>  is the average stress ≠ local stress e =  /L o => e is average strain Final Necking Fracture engg strain d/L o true strain ln(L/L o ) true stress P/A engg stress P/A o fracture Toughness = energy used to fracture = area under true stress-strain curve

15. Ductility Measures how much the material can be stretched before fracture Ductility = 100 x (L f – L o )/L o High ductility: platinum, steel, copper Good ductility: aluminum Low ductility (brittle): chalk, glass, graphite - Walkman headphone wires: Al or Cu?

16. Hardness resistance to plastic deformation by indentation

17. Shear stress and Strain: the torsion test L  C C’  T T L  T T D d T = torque, J = polar moment of inertia J =  r 2 dA Cylindrical shell: J =  D 4  d 4 )/32 Angle of twist:  = TL/GJ Shear stress:  = Tr/J Maximum shear stress =  max = TR/J Shear strain =  = r  /L G: Modulus of rigidity  = G 

18. Shear strength and Tensile strength [approximate relation between shear and tensile strengths] MaterialTensile-RelationYield-Relation Wrought Steel & alloy steelS su ≈ 0.75 x S u S syp = Approx 0,58 x S yp Ductile IronS su ≈ 0.90 x S u S syp = Approx 0,75 x S yp Cast IronS su ≈ 1.3 x S u - Copper & alloysS su ≈ [0.6-0.9] x S u - Aluminum & alloysS su ≈ 0.65 xS u S syp = Approx 0,55 x S yp References: Machine design Theory and Practice.A.D.Deutschman, W.A Michels & C.E. Wilson.. MacMillan Publishing 1975. Ultimate Tensile Strength = S u Ultimate Shear Strength = S su Tensile Yield Strength = S yp Shear yield point = S syp

19. Fatigue Fracture/failure of a material subjected cyclic stresses S-N curve for compressive loading

20. Failure under impact Testing for Impact Strength Application: Drop forging

21. Strain Hardening - Metals microstructure: crystal-grains - Under plastic strain, grains slipping along boundaries - Locking up of grains => increase in strength - We can see this in the true-stress-strain curve also Applications: - Cold rolling, forging: part is stronger than casting

22. Residual stresses Internal stresses remaining in material after it is processed Causes: - Forging, drawing, …: removal of external forces - Casting: varying rate of solidification, thermal contraction Problem: warping when machined, creep Releasing residual stresses: annealing

23. Physical Properties PropertyApplication (e.g.) Density,  = mass/volume Drop forging, hammering Specific heatCoolant in machining Thermal conductivityCutting titanium Coeff of linear thermal expansion,  =  L/(L  T) Compensation in Casting, … Melting pointBrazing, Casting, … Electrical conductivityEDM, ECM, Plating Magnetic propertiesMagnetic chucking

24. Summary Knowledge of materials’ properties is required to Select appropriate material for design requirement Select appropriate manufacturing process Optimize processing conditions for economic manufacturing … Materials have different physical, chemical, electrical properties Reference: Chapter 2, Chapter 3, Mfg Engg & Tech, Kalpakjian & Schmid