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- 1. Grinding
- 2. Common Grinding Processes
- 3. Details of Surface grinding
- 4. Mechanics of GrindingUncut Chip thickness per grit f t1 = mm ZN Where Z = Number of active grains N = rpm of the wheel
- 5. Z = π DCb Where D = Diameter of the wheel C = Surface density of active grains (mm-2) b’ = Average grain width of cut (mm) rg = b / t1 f t1 = π DNCrgPower AfU c W= Where A cross sectional area of the job 60 Uc = Specific energyForce per single grit 60, 000W 1000 fU c Fc= N= N π DACN π DCN
- 6. Chip Formation during surface grinding Dl≈ β 2 D D 2dCos β = ( − d ) / = 1 − 2 2 D β2Cos β ≈ 1 − 2l ≈ Dd 1 (π NDBC ) × bmax t1max l = fdB 6
- 7. 6f d t1max = π NDrg C D BfdU c W= W 60 60, 000W 1000 BfdU c Fc = = π ND π ND Components of Grinding ForceAverage force per grit 60, 000W F = c N π NDCB Dd 369U o f 0.8 d 0.4 rg0.2 N Fc = N 0.8 D1.2C 0.8
- 8. Thermal aspectsEnergy spent per unit surface area ground Fcπ NDθ sα BfSince −0.4 1θ sα dU c and U c = U o (t1av ) and t1av = t1max 2 d 0.9 D 0.3C 0.2 N 0.2θ sα f 0.2 Grain chip interface temperature vt1max θ g = ΘU c k ρC
- 9. Residual stress in workpiece after surface grinding
- 10. Growth of power requirement of different wheel grades
- 11. Grinding Wheel Specification
- 12. Grinding Wheel Wear
- 13. Types of grinding operations
- 14. Honing Operation
- 15. Lapping
- 16. Abrasive Flow Machining (AFM)
- 17. Magnetic Abrasive Finishing (MAF) Sintered ferromagnetic abrasive particle Ferromagnetic abrasive particle in actionMagnetic Abrasive Finishing
- 18. MAFExternal Finishing by MAF Internal Finishing by MAF
- 19. Ideal roughness in turningMaximum height of unevenness where f H max = ψ side cutting edge angle tanψ + cot γ γ end cutting edge angleMaximum height of unevenness, when nose radius (r) is used f2 H max = 8r
- 20. Generation of Ideal roughness in slab milling
- 21. Verification of surface roughness with cutting Speedduring turning mild steel bar
- 22. Economics of Machining Operation
- 23. Optimizing cutting parameters for Minimum costR = R1 + R2 + R3 + R4 + R5 R = Total Cost/ piece R1 = Material Cost/ piece R2 = Set up and idle time Cost/ piece R3 = Machining Cost/ piece R4 = Tool changing Cost/ piece R5 = Tool regrinding Cost/ pieceλ 1= Cost/ min of labour and overheadsλ 2= Cost of setting a tool for regrindingλ3 = Cost/mm of tool groundts = Set-up tme and idel time/ piece, min,tm = Machining time/piece, min,tct = Tool changing time, min
- 24. Set- up and idle time cost R2 = λ1tsMachining cost π LD L = Length R3 = λ1t3 = λ1 D =Diameter 1000 fv f = feedTool Changing cost V = speed tm R4 = λ1 tct T k T = 1/ n 1/ m T = Tool life v f π LD R4 = λ1tct v1/ n −1 f 1/ m −1 1000 fv
- 25. Tool regrinding cost δ = h f tan vs , hf = flank wear δ = Minimum length of tool to be reground λ2 + λ3 = λ2 + λ3h f tanν s tm R5 = (λ2 + λ3 h f tan vs ) T Vs = Clearance angle π LD = (λ2 + λ3 h f tan vs ) v1/ n −1 f 1/ m −1 1000k If tool cost of new tool is A and the total length that can be reground is B mm , then cost per mm of the tool A λ3 = ⎛ B ⎞ 1 + ⎜ h f ⎟ ⎝ ta n v s ⎠
- 26. Total cost per piece π LD π LD π LD R = R1 + λ1ts + λ1 + λ1tct v1/ n −1 f 1/ m −1 + (λ2 + λ3 h f tan vs ) v1/ n −1 f 1/ m −1 1000 fv 1000 fv 1000 fvOptimum speed for a given feed∂R π LD −2 ⎛ 1 ⎞ π LD 1/ n − 2 1/ m −1 = −λ1 v + (λ1tct + λ2 + λ3h f tan vs ) × ⎜ − 1⎟ v f =0∂v vopt 1000 f ⎝ n ⎠ 1000k v = vopt or n ⎡ nk λ1 ⎤vopt =⎢ ⎥ ⎢ (1 − n) f (λ1tct + λ2 + λ3 h f tanν s ) ⎥ 1/ m ⎣ ⎦
- 27. Optimum speed for minimum cost n ⎡ nk λ1 ⎤ vopt =⎢ ⎥ ⎣ (1 − n) f (λ1tct + λ4 ) ⎦ 1/ mOptimum feed for minimum cost m ⎡ mk λ1 ⎤ f opt =⎢ ⎥ ⎣ (1 − m)v (λ1tct + λ4 ) ⎦ 1/ n f max = 8rH max lim H maxlim= Limiting value of unevenness
- 28. Machining force Fc = 1000U 0 wt10.6 Fc = k1 f 0.6 Power consumption Variation of machining cost with v and f W = k1vf 0.6Maximum available power in the machine then limiting cutting speed-feed Wlim vf 0.6 = k1 Selection of optimum feed
- 29. Variation of various costs with cutting speed.
- 30. Optimum cutting parameters for maximum production tm tt = ts + tm + tct min T π LD π LD = ts + + v1/ n −1 f 1/ m −1tct min 1000 fv 1000kFor optimum speed to minimize t1∂tt π LD −2⎛ 1 ⎞ π LD 1/ n − 2 1/ m −1 = v + ⎜ − 1⎟ v f tct =0∂v v = vopt 1000 f ⎝ n ⎠ 1000k v = vopt n ⎡ nk ⎤ vopt =⎢ ⎣ (1 − n) f 1/ mtct ⎥ ⎦
- 31. Optimum cutting seed for maximum efficiency Profit rate S−R S = Amount received per piece pr = tt R and tt can be expressed in terms of v as before, then ∂pr =0 ∂v v = vopt

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