Chapter 7 – Machining Of metals

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However, in practice, the shear plane angle φφφφ is varied depending on the nature of each material (composition & heat treatment) to be machined. Based on the upper bound model of the shear zone, a criterion for predicting φφφφ has been developed. The predicted shear plane angle φφφφ οοοο is given by cos k o ⎡ α ⎞⎤ ( φo − α ) sinφ o = ⎢cos⎜45 − ⎟sin⎜ 45 + ⎟ k ⎥ 1 ⎣ ⎝ 2 ⎠ ⎝ 2 ⎠⎦ ⎛ Suranaree University of Technology Tapany Udomphol Jan-Mar 2007 α ⎞ Where αααα = rake angle ko k1 = σσσσ o /√√√√ 3 and σσσσ o is the yield strength of the material = σσσσ u /√√√√ 3 and σσσσ u is the tensile strength of the material. ⎛ …Eq. 16
cos cos 1 2 ( φ − 6) o Example: Determine the shear plane angle in orthogonal machining with a 6 o positive rake angle for hot-rolled AISI 1040 steel and annealed commercially pure copper. Given Hot-rolled 1040 steel σσσσ o = 415 MPa, σσσσ u = 630 MPa Annealed copper σσσσ o = 70 MPa, σσσσ u = 207 MPa o ( φ − 6) sinφ = ( 0. 552) o o o o ko [ sin 6 + sin( 2φ − 6) ] = ( 0. 552) ⎡ 2φo = ⎢sin ⎣ sinφ = −1 o k k k k ⎛ k ⎜ ⎜1. 104 ⎝ k o 1 1 o 1 ⎡ ⎛ ⎢cos⎜ 45 − ⎣ ⎝ k 1 ⎞⎤ − 0. 1045 ⎟ ⎟⎥ + 6 ⎠⎦ 6 ⎞ ⎛ ⎟sin⎜ 45 + 2 ⎠ ⎝ Note that k o /k 1 is a fraction, then we can use tensile values directly in the above equations. o 6 2 ⎞⎤ ⎟⎥ ⎠⎦ For hot-roll 1040 steel: ⎡ 2φo = ⎢sin ⎣ 2φ = sin Suranaree University of Technology Tapany Udomphol Jan-Mar 2007 φ o o o o = 22. 3 2φ = sin = 10. 8 −1 o o −1 −1 ⎛ ⎜1. 104× ⎝ ( 0. 6227) −1 415 630 + 6 o ⎞⎤ − 0. 1045⎟⎥ + 6 ⎠⎦ = 44. 5 Experimental range is 23 to 29 o For annealed copper: ⎡ 2φo = ⎢sin ⎣ φ ⎛ ⎜1. 104× ⎝ ( 0. 2688) 70 207 + 6 o = 21. 6 o ⎞⎤ − 0. 1045⎟⎥ + 6 ⎠⎦ Experimental range is 11 to 13.5 o o o o
Page 1 and 2: Machining of metals Subjects of int
Page 3 and 4: Introduction Turning of metal www.d
Page 5 and 6: Type of machining operations Classi
Page 7 and 8: Multiple point cutting Removal of t
Page 9 and 10: Electrical discharge machining Remo
Page 11 and 12: Mechanics of machining Geometry of
Page 13 and 14: • The entire chip is deformed as
Page 15 and 16: • The amount of primary shear is
Page 17 and 18: The cutting speed There are three v
Page 19 and 20: Shear strain rate in cutting • d
Page 21 and 22: • If the components of the cuttin
Page 23: • We need to know the shear angle
Page 27 and 28: The specific cutting energy U depen
Page 29 and 30: If a toolpost dynamometer gives cut
Page 31 and 32: Type of machining chips Three gener
Page 33 and 34: Chip with a built-up edge (BUE) •
Page 35 and 36: x Three-dimensional Three dimension
Page 37 and 38: Multiple-edge cutting tools Drillin
Page 39 and 40: Temperature in metal cutting Temper
Page 41 and 42: Cutting fluids • The cutting flui
Page 43 and 44: Tool materials and tool life Proper
Page 45 and 46: Two main types of wear in cutting t
Page 47 and 48: Tool materials Carbon and low alloy
Page 49 and 50: Cemented carbides Cemented carbides
Page 51 and 52: Ceramics or oxide tools There are t
Page 53 and 54: Tool performance • Tool performan
Page 55 and 56: Taylor equation • Cutting speed i
Page 57 and 58: Machinability Definition: The abili
Page 59 and 60: Grinding process Grinding processes
Page 61 and 62: • Wheel performance is controlled
Page 63 and 64: Specific cutting energy The specifi
Page 65 and 66: Grindability Grindability is measur
Page 67 and 68: Non-traditional Non traditional mac
Page 69 and 70: Electrochemical machining (ECM) •
Page 71 and 72: Chemical machining (CHM) • Metal
Page 73 and 74: Economics of machining Speed , feed
Page 75 and 76:
3) Cost of tool changing The cost o
Page 77 and 78:
Variation of machining costs with c
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Chapter 7 – Machining Of metals

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