Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege.edu

1. Engineering 11 MaterialsSelection Bruce Mayer, PE Licensed Electrical & Mechanical EngineerBMayer@ChabotCollege.edu

2. Customer Needs Formulation Customer requirements Importance weights Eng. characteristics House of Quality Eng. Design Spec’s Concept Design Abstract embodiment Physical principles Material Geometry ? Configuration Design Materials Selection at Config

3. Matls & Manuf  Closely Linked Problem Formulation Concept Design manufacturing processes materials Configuration Design ParametricDesign DetailDesign

4. COMPATIBLE materials & processes Matls & Manuf  Closely Linked • e.g.; Ceramics can NOT be WELDED Material Properties Manufacturing Processes

5. CAPABLE Processes for the geometry Matls & Manuf  Closely Linked • e.g.; CAST Parts can NOT have SHARP Corners Manufacturing Processes Product Geometry

6. Matl↔Manf↔Geom  Function Material Properties Product Function Manufacturing Processes Product Geometry

7. Properties of Solid Materials • Mechanical: Characteristics of materials displayed when Forces or Moments are applied to them. • Physical: Characteristics of materials that relate to the interaction of materials with various forms of energy. • Chemical: Material characteristics that relate to the Material’s electron structure. • Dimensional: Size, shape, and finish

8. Material Properties Chemical Physical Mechanical Dimensional Composition Melting Point Tensile properties Standard Shapes Microstructure Thermal Toughness Standard Sizes Phases Magnetic Ductility Surface Texture Grain Size Electrical Fatigue Stability Corrosion Optical Hardness Mfg. Tolerances Crystallinity Acoustic Creep Molecular Weight Gravimetric Compression Flammability • One More ≡ $COST, $COST, $COST

9. Materials Metals Plastics Ceramics Composites Ferrous Thermoplastics Thermosets Non-ferrous Sub-family Elastomers Solid-Materials Family Tree See Also ENGR45

10. Family Sub-family Classes Solid-Materials Taxonomy Materials Metals Ferrous Cast iron Carbon steel Alloy steel Stainless steel

11. Metals Family Tree Metals Ferrous (Mostly Iron) Non-ferrous cast iron carbon steel alloy steel stainless steel aluminum brass bronze copper lead magnesium nickel tin titanium tungsten zinc

12. Polymer (Plastics) Family Tree Polymers Thermoplastics Thermosets Elastomers ABS acetal acrylic nylon polycarbonate polyethylene polypropylene polystyrene vinyl alkyd epoxy melamine phenolic polyester urethane butyl fluorocarbon neoprene nitrile polysulfide rubber silicone

13. Ceramics & Composites Trees Ceramics Composites carbon fiber ceramic matrix glass fiber Kevlar fiber metal matrixpolymer matrix alumina beryllia diamond magnesia Silicates Silica carbide Nitride Oxide zirconia

14. Material Family Comparison

15. Materials Selection Strategy prospective materials and processes rejected materials and processes functional? manufacturable? screening feasible materials and processes relative performance? rating best material(s) and processes

16. Materials Selection • The designer of any product, other than software, must be part of the material selection process. • Only occasionally will the exact grade of material be specified by the customer. • Even then the designer must UNDERSTAND the material to be able to design the product.

17. Decisions, Decisions! • So many materials, so much information. • How do we decide? • How do we even begin to choose? • Metals are the DEFAULT as they have the widest variety of Manufacturing Processes • First we need to look at the function of the product • Use PRODUCT ANALYSIS

18. Product Analysis • Just what it says – analyze the product! • What does it do? • How does it do it? • Where does it do it? • Who uses it? • What should it cost?

19. Case Study  BiCycle • What is the function of a bike – obvious? • How does the function depend on the type of bike? • Racing • Touring • Mountain • Commuter • Child’s

20. Case Study  BiCycle (2) • How is it made to be easily maintained? • What should it look like (colors etc.)? • What should it cost? • Child’s Bike VS. Professional Racing Bike • How has it been made comfortable to ride? • How do the mechanical parts work and interact?

21. Component or System? • 1st problem is……. Is a BiCycle one component or a system of components working together? • e.g.; a one-piece Bracket is a component, a Cordless Screwdriver is a system.

22. System Analysis • When we analyze a system we need to break the system down into individual components and then analyze each one for the best Matl. • CordLess ScrewDriver BreakDown A Nice EXPLODED-View (Assembly) Drawing

23. System Analysis  BiCycle • The bike breaks down (Not Literally, we hope) into various parts: • Frame & Forks • Wheels & Brakes • Seat & Peddles • Gears & Chain • Safety (reflectors) • etc. 

24. System Analysis  BiCycle • Now need to look at the following for each part: • Requirements (mechanical, ergonomic, aesthetic etc.) • Function • How many are going to be made? • What manufacturing methods are we going to use?

25. Manufacturing InterDependency • YES!...We have to actually MAKE it! • This is a key question which has a HUGE influence on materials selection. • e.g., what materials could we use for the FRAME?

26. Frame Material Candidates • Steel • Strong, stiff, HEAVY, Inexpensive, Easy to Join • Aluminum • WEAKER, lighter, MORE EXPENSIVE than steel, Hard to Join • Composite (CFRP) • strong, stiff, very light, but MOST EXPENSIVE

27. Bike Frame

28. Frame JointDetail • A Critical Manufacturing Process Detail • Weld? • Braze? • Shrink Fit? • Other?

29. Where do I find Materials data? • Textbooks • Databooks • Manufacturer’s literature • Internet Sites • CurrentDefault • Most DataBooksare OnLine

30. Textbooks • Good for general information • Some have tables of properties • Not good for detailed specifications and properties. • A useful starting point

31. Databooks • One of the quickest sources of detailed information. • Usually contain grades and specifications as well as properties. • Small and perfectly formed – pocketbooks • Easy to navigate around

32. Manufacturer’s literature • Variable in quality and usefulness. • Often only cover their products. • Usually do not compare materials. • Can be biased. • Good for final selection before ordering.

33. InterNet Sites • Can be a real minefield. • Lots of poorly presented information. • Google searches bring up lots of SuperFluous info. • Hard to find technical information. • Best to use non-commercial sites.

34. MatWeb.com is VERY Good for Props

35. Materials Selection Charts • Allow easy visualization of properties • Show lots of different materials • Can be ‘drilled down’ to specifics • Show balances of properties e.g. strength vs cost • Ideal for a first ‘rough cut’ selection

36. TradeOff Weight & Stiffness

37. Modulus - Density Chart • Modulus spans 5 orders of magnitude • 0.01 GPa for foams to 1000 GPa for diamond • The charts therefore use logarithmic scales, where twice the distance means ten times the property value. • This makes it possible to show the full range on one chart,

38. TradeOff Weight & Strength

39. TradeOff Insulation & Expansion

40. Summary  Matls Selection • Think about the design from ergonomic and functional viewpoint. • Decide on the materials to be used. • Choose suitable manufacturing processes that are also economic • Steps 2 & 3 may be iterative. Don’t forget the …………… NextSlide

41. Bigger Picture (don’t forget) • Is the product PERFORMANCE driven or COST driven? • This makes a huge difference when choosing materials. • Kid’s bike vs. Racing bike

42. Manufacturing Priority • Although we usually choose materials FIRST sometimes it is the SHAPE and PROCESS which is the limiting factor. • e.g.; Complex HiVacuum Chambers almost always must be WELDED to form GasTight Seals • Limits Materials Selection to METALS

43. Summary  Materials Selection • Product function interdependence • Mechanical properties • Physical properties • Families, sub, classes of materials • TradeOff (Ashby) charts • Materials first approach • Process first approach

44. All Done for Today AnotherAshbyChart

45. Engineering 11 Appendix Bruce Mayer, PE Registered Electrical & Mechanical EngineerBMayer@ChabotCollege.edu

46. What is an Ashby Chart? • It’s a form of a picture that’s worth well more than a 1000 words for any engineering designer. Named for Prof. M. F .Ashby, this is a tool that’s less widely used than it should be. • The chart involves plotting “clouds” on a 2-axis plot, with different variables on each axis. Sounds simple, but the impact doesn’t hit you till you actually see them, as in this example from Granta above: