| 1. |
- Mallipeddi, Dinesh, 1987, et al.
(författare)
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Surface integrity of machined electron beam melted Ti6Al4V alloy manufactured with different contour settings and heat treatment
- 2020
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 87:20, s. 327-332
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Konferensbidrag (refereegranskat)abstract
- The powder-bed-fusion-based Electron Beam Melting (EBM) is rapidly gaining interest as a feasible process in the manufacturing industry for producing intricate Ti6Al4V components. However, there is still a challenge of reducing production time and optimizing surface roughness. One way to improve surface roughness is to optimize the melting strategy, i.e. contour setting. This not only influences the obtained surface topographical features, but also the production time. Most industrial applications require subtractive post processing (machining) to obtain a desired functional surface. This paper is concerned with analysing surface and subsurface in turning of Ti6Al4V alloy, manufactured by EBM using different contour settings. Also, the effect of subsequent heat treatment, i.e. Hot Isostatic Pressing (HIP) is studied. The results indicate that avoiding of contours require a machining allowance of 1 mm to obtain surface roughness of about 0.5 µm (Sa). In case of three and five contours the machining allowance can be reduced to 0.25 mm. Microstructural differences originating from the subsequent HIP operation show no effect on machinability. Tensile residual stresses are generated when reaching down to the heat effected zone of contour settings.
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| 2. |
- Pusavec, Franci, et al.
(författare)
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Tribology of solid-lubricated liquid carbon dioxide assisted machining
- 2020
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 69:1, s. 69-72
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made into the lubrication capabilities of solid-lubricated liquid carbon dioxide (LCO2) in comparison to flood lubrication, straight LCO2 and oil-lubricated LCO2 (MQL). The coefficient of friction is determined via tribological experiments, similar to machining, using an open tribometer which features an uncoated carbide insert sliding against a workpiece. Tribological experiments reveal superior performance of solid-lubricated LCO2. The milling experiments as well indicate that solid-lubricated LCO2 significantly reduces wear. The machined-surface topography is examined using high-magnification SEM, which shows no presence of adhered solid particles on the workpiece surface, providing a completely dry machining process.
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| 3. |
- Sterle, Luka, et al.
(författare)
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The influence of single-channel liquid CO2 and MQL delivery on surface integrity in machining of Inconel 718
- 2020
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 87, s. 164-169
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Konferensbidrag (refereegranskat)abstract
- Sustainable machining of difficult-to-cut materials requires effective cooling and lubrication techniques. To substitute conventional flood cooling and lubrication, different techniques such as cryogenic cooling and/or minimum quantity lubrication (MQL) can be used. Liquid carbon dioxide (LCO2) can be pre-mixed with different lubricants before its delivery to the cutting zone. This article investigates the influence of this recently developed cooling and lubrication method on surface integrity characteristics in milling of Inconel 718. Surface roughness, surface topography and microstructure were evaluated for flood lubrication, dry cutting and LCO2 machining using a single-channel LCO2 and MQL strategy. Moreover, two different lubricants were evaluated for MQL: (i) conventional MQL oil and (ii) solid lubricant molybdenum di-sulphide (MoS2). In addition to being environmentally friendly, MoS2 lubricated LCO2 showed comparable surface characteristics to flood lubrication. Also, the use of lubricated LCO2 resulted in higher part surface cleanliness compared to flood lubrication.
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