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A Study of Cutting Forces and Surface Finish in High-Speed Machining of AISI H13 Tool Steel Using Carbide Tools With TiAIN Based Coating Authored by: P.

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Presentation on theme: "A Study of Cutting Forces and Surface Finish in High-Speed Machining of AISI H13 Tool Steel Using Carbide Tools With TiAIN Based Coating Authored by: P."— Presentation transcript:

1 A Study of Cutting Forces and Surface Finish in High-Speed Machining of AISI H13 Tool Steel Using Carbide Tools With TiAIN Based Coating Authored by: P T Mativenga & K K B Hon Presented by: Ted Hand October 27, 2004

2 Introduction Process improvement should not compromise but should enhance product quality. Purpose of the paper: Address the effects of increasing machining speeds as well as the effects of different advanced coatings on surface finish.

3 Background Coatings Coatings TiC coatings TiC coatings Reduce cutting T, forces, and increase abrasion resistance as well as acting as a diffusion barrier. Reduce cutting T, forces, and increase abrasion resistance as well as acting as a diffusion barrier. Expand the region of machining conditions which reduces wear rates Expand the region of machining conditions which reduces wear rates Coatings are expected to result in lower wear regions occurring at higher spindle speeds, promoting the use of HSM.

4 Surface Roughness Definition: relatively closely spaced or fine surface irregularities, mainly in the form of feed marks left by the cutting tool. Definition: relatively closely spaced or fine surface irregularities, mainly in the form of feed marks left by the cutting tool. Surface roughness: R a = S 2 z / (18 x (3(D/2 + S z N t / pi)).5 ) Surface roughness: R a = S 2 z / (18 x (3(D/2 + S z N t / pi)).5 ) D = tool diameter D = tool diameter S z = V f / N t N = chip load S z = V f / N t N = chip load N t = number of edges that advance in a revolution of the cutter N t = number of edges that advance in a revolution of the cutter N = spindle speed in r/min N = spindle speed in r/min V f = feed rate V f = feed rate

5 Parameters Machine tool: Mikron HSM 700 Mikron HSM r/min 12 kw spindle capable of a 20m/min cutting feed and 40 m/min rapid feed Cutting tools: 6mm ball-nose end mills 6mm ball-nose end mills PVD coated PVD coated Micrograin alloy WC 10% Co Micrograin alloy WC 10% Co

6 Table 1: Geometrical properties of the ball-nose end mill used in the experiments Tool parametersSymbolValue Number of flutes 2°° Helix angleλ30° Rake angleγ0° Shank diameterd6mm Overall tool lengthltlt 57mm Nominal length below chuckl norm 20mm Cut lengthlclc 7mm Cutter diameterd6mm Corner Radiusr3mm Setting angleχ0°

7 Table 2: Properties of PVD coatings Coating materialTiNTiCNCrN2TiAlNTiAlN TiAlN + WC/C Microhardness (HV Coefficient of friction against steel (dry) Coating thickness (μm) Maximum working temperature (°C)

8 Work material: Mid range hot work tool steel AISI H13 Mid range hot work tool steel AISI H13 Finishing operations use the following coatings: TiN TiN TiCN TiCN CrN CrN TiAlN TiAlN 2TiAlN 2TiAlN TiAlN + WC/C TiAlN + WC/C Three components of the cutting forces were sampled and averaged. Cont.

9 Milling Strategy Table 3: Cutting parameters for AISI H13 tool steel HSM experiments Tool diameter D6mm Depth of cut a.06mm Width of cut b.06mm Rapid feed V f-rapid 10,000 mm/min Ramp feed V f-ramp 500 mm/min Cutting feed VfVfVfVf 6000 mm/min Direction of linear interpolation x axis Direction of tool step-over y axis

10 Evaluation Surface finish was evaluated using a Mitutoyo SURFTEST 301 with a cut- off value of.8mm and a span of.5mm Surface finish was evaluated using a Mitutoyo SURFTEST 301 with a cut- off value of.8mm and a span of.5mm 25 measurements taken 25 measurements taken Surface integrity studied with a optical microscope and an SEM Surface integrity studied with a optical microscope and an SEM

11 Results Table 4: Correlation coefficients of surface finish to cutting forces Step-over direction G01 direction FxFxFxFx FyFyFyFy FzFzFzFz Peak F z FxFxFxFx FyFyFyFy FzFzFzFz TiN TiCN CrN TiAlN Uncoated TiAlN TiAlN + WC/C

12 Graphs Figures 2-10 Figures 2-10 –How the surface finished is affected by the spindle speed.

13 HSM with TiCN, TiN, CrN, single and double layered TiAlN produced a better surface finish HSM with TiCN, TiN, CrN, single and double layered TiAlN produced a better surface finish TiAlN gave the best results, but need to minimize interaction with steel TiAlN gave the best results, but need to minimize interaction with steel CrN didnt present an advantage CrN didnt present an advantage Cont.

14 Conclusions PVD tool coatings improved the surface finish compared to uncoated tools PVD tool coatings improved the surface finish compared to uncoated tools Coatings had the smallest wear zone promoting higher cutting speeds Coatings had the smallest wear zone promoting higher cutting speeds Higher cutting speeds and PVD coatings are pushing the frontiers in surface finishing's. Higher cutting speeds and PVD coatings are pushing the frontiers in surface finishing's.

15 Implications Reducing die making lead times Reducing die making lead times Cutting costs with smaller lead times Cutting costs with smaller lead times Industries affected: Industries affected: Aerospace Aerospace Precision machine labs Precision machine labs Auto industry Auto industry Etc. Etc.

16 References: Edwards, R. Cutting Tools, 1993, pp (The institute of Materials) Edwards, R. Cutting Tools, 1993, pp (The institute of Materials) ISO 368 Surface RoughnessParameters, Their Values and General Rules for Specifying Requirements ISO 368 Surface RoughnessParameters, Their Values and General Rules for Specifying Requirements Lim, S.C. and Lim, C.Y.H. Effective use of coated toolsthe least wear map approach. Surface and Coatings Technol., 2001, 139, Lim, S.C. and Lim, C.Y.H. Effective use of coated toolsthe least wear map approach. Surface and Coatings Technol., 2001, 139, Konig, W., Komanduri, R., Tonshoff, H.K. and Ackershott, G. Machining of hard materialsKey Note papers. Ann. CIRP, 1984, 33(2), Konig, W., Komanduri, R., Tonshoff, H.K. and Ackershott, G. Machining of hard materialsKey Note papers. Ann. CIRP, 1984, 33(2), DeVries, W.R. Analysis of Material Removal Processes, 1992, p.138 (Springer - Verlag, Berlin). DeVries, W.R. Analysis of Material Removal Processes, 1992, p.138 (Springer - Verlag, Berlin). Da Silva, M.B. and Wallbank, J. Lubrication and application method in machining. Ind. Lubric. Technol., 1998, 50(4), Da Silva, M.B. and Wallbank, J. Lubrication and application method in machining. Ind. Lubric. Technol., 1998, 50(4),


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