EI 202 Manufacturing Processes

1. EI 202 Manufacturing Processes • Dr. Apiwat Muttamara

2. Classifications of Metal Alloys Metal Alloys Ferrous Nonferrous Steels Cast Irons Steels Cast Irons Cu Al Mg Ti <1.4wt%C <1.4wt%C 3-4.5 wt%C 3-4.5 wt%C • Ferrous alloys: iron is the prime constituent • -Alloys that are so brittle that forming by • deformation is not possible ordinary are cast

3. Materials 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

4. Common properties of metals. • Chemical properties…ex. Corrosion resistance. • Physical properties…color, density, weight, electrical and heat conductivity. • Mechanical properties…are determined when outside forces are applied to a metal.

5. Many of the properties of steel are affected by: Carbon content Impurities (sulfur, phosphorus and slag) Addition of alloys such as chromium Heat treatment Properties of Iron and Steel

6. HISTORY OF METALS • 86 Metals known today • Only 24 discovered before 19th century • Earliest metals were gold (6000BC) and copper (4200BC) • Seven Origin were: Gold( 6000BC), Copper( 4200BC), Silver (4000BC), Lead (3500BC), Tin (1750BC), Smelted Iron (1500BC) and Mercury ( 750BC)

7. HISTORY OF METALS • Although several metals occur in the earth’s crust in their native state, the early civilizations learned to process ores -- usually metal sulfides or oxides -- by reduction or oxidation processes at elevated temperatures. • At first, this probably happened by accident, when these ores were dropped into campfires. • By smelting tin ores with copper ores a new kind of “copper” was produced that was stronger and easier to cast.. This was discovery of bronze.

8. Melting of Materials

9. Designation Wrought Iron Low Carbon Medium Carbon High Carbon Very High Carbon Gray Cast Iron % Carbon .02 - .03 .05 - .30 .30 - .45 .45 - .75 .75 - 1.00 1.7 - 4.5 Steel Percent of carbon in Iron Iron with controlled amounts of carbon. Steels are classified by their carbon content.

10. T(°C) 1600 d L 1400 g +L g 1200 L+Fe C 3 1148°C austenite Eutectic 4.30 1000 Fe C 3 g a +Fe C 3 + 800 cementite a g 727°C Eutectoid a 6 00 0.77 +Fe C 3 4 00 0 1 2 3 4 5 6 6.7 (Fe) Carbon concentration, wt% C Steel generally has less than about 0.7% C, but can have up to 1.4 (2.11theory) % C.

11. Summary: Steels • Low-Carbon Steels • Properties: nonresponsive to heat treatments; relatively soft and weak; machinable and weldable. • Typical applications: automobile bodies, structural shapes, pipelines, buildings, bridges, and tin cans. • Medium-Carbon Steels • Properties: heat treatable, relatively large combinations of mechanical characteristics. • Typical applications: railway wheels and tracks, gears, crankshafts, and machine parts. • High-Carbon Steels • Properties: hard, strong, and relatively brittle. • Typical applications: chisels, hammers, knives, and hacksaw blades. • High-Alloy Steels (Stainless and Tool) • Properties: hard and wear resistant; resistant to corrosion in a large variety of environments. • Typical applications: cutting tools, drills, cutlery, food processing, and surgical tools.

12. Standards Designation Equivalent of Tool Steels ---

17. Stainless Steel • >10% Chromium • May also contain large amounts of nickel • The austenite structure survives at room temperature • Makes the steel especially corrosion resistant • Non magnetic-Only martensitic stainless

20. Metal Cutting 1.Traditional Machine • Turning • Milling etc. 2. Non-traditional Machine • Laser, EDM etc. Chip

21. Turning

22. Propose • The operational uses and parameters, • The general layout of controls, accessories, associated tooling • It takes a considerable time to become a skilled lathe operator and to possess all the skill of hand that goes with it. Therefore it is not expected that you will be manually skilled on completion of the module but you will have gained intellectually, by practical involvement, some skill of hand will be achieved.

23. apron Centre Lathe

24. Bed - the main frame,H-beam on 2 V-support • It has guideways for carriage to slide easilylengthwise Headstock • The spindle is driven through the gearbox Tailstock - Quill- Lath center, Tooling reference • Drill

25. A Plain Lath Center Quill Tailstock Chuck

26. Producing a Cylindrical Surface

27. Figure 2c. Taper Turning • Figure 2e. Radius Turning Attachment

28. Cutting Tools

31. CHUCK JAW Bevel pinion Bevel gear with spiral scroll

32. Face Plate Counterweght Workpiece

33. Face plate Dog Workpiece Lathe Center

34. Steady rest Three Adjustable Jaws

35. Basic Metal Cutting Theory RAKE Relief

36. Main Features of a Single Point Cutting Tool

37. Rake Angle • The larger the rake angle, the smaller the cutting force on the tool, • A large rake angle will improve cutting action, but would lead to early tool failure • A compromise must therefore be made between adequate strength and good cutting action. Clearance Angle Clearance should be kept to a minimum, as excessive clearance angle will not improve cutting efficiency and will merely weaken the tool.

38. Characteristics of Tool Material • Hot Hardness • the ability to retain its hardness at high temperatures. • Strength and Resistance to Shock • At the start of a cut the first bite of the tool into the work results in considerable shock • Low Coefficient of Friction

39. Tool Materials in Common Use • High Carbon Steel • Contains 1 - 1.4% carbon with some addition of chromium and tungsten to improve wear resistance. • The steel begins to lose its hardness at about 250° C, and is not favoured for modern machining operations where high speeds and heavy cuts are usually employed. • High Speed Steel (H.S.S.) • Steel, which has a hot hardness value of about 600° C, • commonly used for single point and multi point cutting tools • Cemented Carbides (WC-Co) • An extremely hard material made from tungsten powder. • Carbide tools are usually used in the form of brazed or clamped tips • HSS may be readily machined using carbide tipped tool. • High cutting speeds may be used and materials difficult to cut with HSS

41. Blade material and major uses

42. TiC or TiN or TiCN, Al2O3 WC-Co Coating Materials for Cutting tool PCD Polycrystalline Diamond CBN Cubic Boron Nitride

44. CERMET Ceramic+metal

45. Chip Formation & Chip Breaker material & cutting conditions These conditions include the type of tool used tool, rate of cutting condition of the machine and the use or absence of a cutting fluid.

46. Continuous Chip - The chip leaves toolsa long ribbon -common when cutting most ductile materials such as mild steel, copper and Aluminium. Ideal Chip It is associated with good tool angles, correct speeds and feeds, and the use of cutting fluid.

47. Discontinuous Chip -resulted from cutting brittle metals such as cast iron and cast brass with tools having small rake angles. There is nothing wrong with this type of chip in these circumstances

48. Continuous Chip with Builtup Edge(BUE) This is a chip to be avoided and is caused by small particles from the workpiece becoming welded to the tool face under high pressure and heat. The phenomenon results in a poor finish and damage to the tool. It can be minimised or prevented by using light cuts at higher speeds with an appropriate cutting lubricant

49. Cutting Speed • Where: N = Spindle Speed (RPM)CS = Cutting Speed of Metal (m/min)d = Diameter of Workpiece

50. Cutting Speed