| 1. |
- Ahmed, N., et al.
(författare)
-
Process parameter selection and optimization of laser powder bed fusion for 316L stainless steel : A review
- 2022
-
Ingår i: JOURNAL OF MANUFACTURING PROCESSES. - : Elsevier BV. - 1526-6125. ; 75, s. 415-434
-
Forskningsöversikt (refereegranskat)abstract
- Stainless steel 316L has been an extensively investigated metallic material for laser powder bed fusion (L-PBF) in the past few decades due to its high corrosion resistance. However, there are challenges related to producing LPBF parts with minimal defects, attaining mechanical properties comparable with traditional process and dependency on time consuming post process treatments. The selection of L-PBF process parameters is crucial to overcome these challenges. This paper reviews the research carried out on L-PBF process parameter optimization for fabrication of 316L steel components for maximizing part densifications and attaining desired microstructure morphologies in parts. A brief work on numerical simulation approach for process parameter optimization for high densifications is also included in this paper.
|
|
| 2. |
|
|
| 3. |
- Bournias-Varotsis, Alkaios, et al.
(författare)
-
Ultrasonic Additive Manufacturing as a form-then-bond process for embedding electronic circuitry into a metal matrix
- 2018
-
Ingår i: Journal of Manufacturing Processes. - London : Elsevier. - 1526-6125. ; 32, s. 664-675
-
Tidskriftsartikel (refereegranskat)abstract
- Ultrasonic Additive Manufacturing (UAM) is a hybrid manufacturing process that involves the layer-by-layer ultrasonic welding of metal foils in the solid state with periodic CNC machining to achieve the desired 3D shape. UAM enables the fabrication of metal smart structures, because it allows the embedding of various components into the metal matrix, due to the high degree of plastic metal flow and the relatively low temperatures encountered during the layer bonding process. To further the embedding capabilities of UAM, in this paper we examine the ultrasonic welding of aluminium foils with features machined prior to bonding. These pre-machined features can be stacked layer-by-layer to create pockets for the accommodation of fragile components, such as electronic circuitry, prior to encapsulation. This manufacturing approach transforms UAM into a “form-then-bond” process. By studying the deformation of aluminium foils during UAM, a statistical model was developed that allowed the prediction of the final location, dimensions and tolerances of pre-machined features for a set of UAM process parameters. The predictive power of the model was demonstrated by designing a cavity to accommodate an electronic component (i.e. a surface mount resistor) prior to its encapsulation within the metal matrix. We also further emphasised the importance of the tensioning force in the UAM process. The current work paves the way for the creation of a novel system for the fabrication of three-dimensional electronic circuits embedded into an additively manufactured complex metal composite. © 2018 The Society of Manufacturing Engineers
|
|
| 4. |
- Broqvist, Natalia, et al.
(författare)
-
On wear resistance of tool steel
- 2012
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 14:3, s. 195-198
-
Tidskriftsartikel (refereegranskat)abstract
- Maintaining a reasonably low cutting tool wear when producing forming tools is a general challenge in the development of new forming tool materials. The tool life of a hot forming tool steel (H13) has been significantly improved by reducing its Si-content from 1.0 to 0.06 wt.%. However, this modified H13 (MH13) also displays a reduced cutting tool life due to higher cutting forces and a stronger tendency to form built up layers (BUE) on the cutting edge. This paper explains why.Gleeble tests of MH13 revealed a significantly higher flow stress in the 820–900 °C temperature interval in MH13 compared to H13. Thermo-Calc simulations showed that when reducing the Si-content from 1.0 to 0.06 wt.% the initial temperature for ferrite-to-austenite transformation (A1) was reduced from 900 °C to 820 °C. Knowing that austenite has totally different mechanical and thermal properties than ferrite, the difference in A1 between the two steels explains the higher cutting forces and higher tendency for BUE-formation. The conclusion is that the difference in machinability between H13 and MH13 is primarily related to their difference in A1.An attempt was also made to find a new tool material composition that can combine the wear resistance of MH13 and the good machinability of H13. Thermo-Calc simulations were performed with slightly modified alloying content without changing its properties as a good forming tool material, with the aim to increase A1. For instance, reducing the Mn content from 0.5 to 0.05 wt.% proved to increase A1 from 820 to 850 °C.
|
|
| 5. |
- Bunaziv, Ivan, et al.
(författare)
-
Filler metal distribution and processing stability in laser-arc hybrid welding of thick HSLA steel
- 2020
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 54, s. 228-239
-
Tidskriftsartikel (refereegranskat)abstract
- Welds made by high power laser beam have deep and narrow geometry. Addition of filler wire by the arc source, forming the laser-arc hybrid welding (LAHW) process, is very important to obtain required mechanical properties. Distribution of molten wire throughout the entire weld depth is of concern since it tends to have low transportation ability to the root. Accurate identification of filler metal distribution is very challenging. Metal-cored wires can provide high density of non-metallic inclusions (NMIs) which are important for acicular ferrite nucleation. Accurate filler distribution can be recognized based on statistical characterization of NMIs in the weld. In the present study, it was found that the amount of filler metal decreased linearly towards the root. The filler metal tends to accumulate in the upper part of the weld and has a steep decrease at 45–55 % depth which also has wavy pattern based on longitudinal cuts. Substantial hardness variation in longitudinal direction was observed, where in the root values can reach > 300 HV. Excessive porosity was generated at 75 % depth due to unstable and turbulent melt flow based on morphology of prior austenite grains. The delicate balance of process parameters is important factor for both process stability and filler metal distribution.
|
|
| 6. |
- Chen, Zhuoer, 1989, et al.
(författare)
-
Influence of part geometry on spatter formation in laser powder bed fusion of Inconel 718 alloy revealed by optical tomography
- 2022
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 81, s. 680-695
-
Tidskriftsartikel (refereegranskat)abstract
- The metal powder used during the Laser Powder Bed Fusion (L-PBF) process is usually cycled for reuse in subsequent build jobs for cost-effectiveness and sustainability. Qualification guidelines are being established based on testing results of powder properties in terms of flowability, chemistry and rheological behaviors, etc. for making decisions on whether a batch of reused powder is suitable for producing parts that meet certain requirements. The current paper aims to develop experimental strategies for tracking powder history using novel design of specimens and on-line monitoring. Powder-capturing containers designed with internal lattice structures of varied beam lengths and diameters were manufactured by the L-PBF process using an Inconel 718 powder to investigate the influence of part geometry on the degradation of reused powder. The L-PBF experiment was monitored by a commercial Optical Tomography (OT) system which records the thermal emissions from the build area. Data were extracted from the OT images to evaluate the emissions of spatter particles introduced to the powder bed, which is influenced by the local layer profiles of the lattices and the overall geometries of the container. The collected powder samples were tested by combustion analysis for oxygen content and characterized by Scanning Electron Microscopy (SEM). Surface chemistry analyses of the powders were performed by X-ray Photoelectron Spectroscopy (XPS). Depending on the lattice structure geometry, the oxygen uptake in the powder collected from the containers was increasing by 10 ppm in case of empty container and up to as high as 118 ppm in case of container with larger areas of overhangs and higher surface-to-volume ratio. XPS results revealed the presences of Al-rich and Cr-rich oxides on the surface of powder samples collected from the container filled with lattices of high surface-to-volume ratio and the container filled with lattices of large overhangs, which agrees with the analyses of OT data.
|
|
| 7. |
- Chen, Zhan, et al.
(författare)
-
Iteration based calculation of position and orientation of grinding wheel for solid cutting tool flute grinding
- 2018
-
Ingår i: JOURNAL OF MANUFACTURING PROCESSES. - : ELSEVIER SCI LTD. - 1526-6125. ; 36, s. 209-215
-
Tidskriftsartikel (refereegranskat)abstract
- End mill cutting tools are widely used in machining of curved surface parts in many areas, e.g. aerospace, automobile, and energy. The parameters of helical groove cross section, influencing chip removal capacity, include rake angle, core radius and edge width. Towards a parametrical control algorithm of the cutting tool flute, this paper proposed an iteration based method. Within the context, the cutting tool parameters and grinding wheel are set firstly. Then, three angle parameters, alpha, beta, and theta in the grinding coordinate system, are looped. In each loop, one of the target flute parameters is compared with the pre-set values, and if the parameter is within the range, the calculation goes the next loop until the parameters are in the target range. Since the loop number is so high that the computing time is too long, the patterns between the flute parameters and looped parameters are used to improve the calculation speed. The method is implemented by using C#, and validated by a set of numeric simulation based on Matlab (R).
|
|
| 8. |
- Da Silva, Adrien, et al.
(författare)
-
Melt pool monitoring and process optimisation of directed energy deposition via coaxial thermal imaging
- 2023
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 107, s. 126-133
-
Tidskriftsartikel (refereegranskat)abstract
- In Laser-based Directed Energy Deposition of metal powder, the use of optimised parameters allows the deposition of defect-free material, while diverging from these optimised parameters can typically result in high porosity, high dilution or different track geometry. One of the main challenges when building complex geometries is that the geometrical and thermal conditions of the deposition are constantly changing, which requires to adjust the process parameters during the production. In order to facilitate this process, sensors such as thermal cameras can be used to extract data from the process and adapt the parameters to keep the process stable despite external disturbances. In this research, different signals extracted from a coaxial thermal camera are investigated and compared for process optimisation. To investigate such possibilities, five overlapped tracks are deposited at constant laser powers in order to extract average pixel values as well as the melt pool area, length, width and orientation. The behaviour of each track deposition is modelled as a function of the laser power, and these models are used to calculate and test laser power reduction strategies based on different signals. The results show that the melt pool area is the most relevant signal to use for an efficient process control, resulting in a stable process with only ±1.6 % of signal variation from track to track.
|
|
| 9. |
- de Andrade Schwerz, Claudia, 1992, et al.
(författare)
-
Increasing productivity of laser powder bed fusion manufactured Hastelloy X through modification of process parameters
- 2022
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 78, s. 231-241
-
Tidskriftsartikel (refereegranskat)abstract
- One of the factors limiting the use of additive manufacturing, particularly powder bed processes, is their low productivity. An approach to increasing laser powder bed fusion (LPBF) build rate without costly hardware modifications is to alter process parameters. This study evaluates the possibilities to increase build rates through this route without compromising material quality. Equations for productivity are derived based on process parameters and build geometry, and applied on the process window for Hastelloy X in LPBF. It is demonstrated that virtually flaw-free parts can be printed at build rates that differ up to tenfold. To investigate potential variations in the microstructure and performance, Hastelloy X specimens manufactured at varying build rates were characterized. Electron backscattered diffraction (EBSD) analysis revealed that the specimen built at the lowest rate shows strong texture with columnar grains, while the specimen built at the highest rate presents significantly more random orientation and evident melt pool contours with pockets of very fine grains at the bottom. Despite the major differences in microstructure, the tensile properties do not necessarily vary substantially. Thus, the results indicate that the build rate of LPBF Hastelloy X can be significantly varied based on process parameters, still yielding consistent mechanical properties.
|
|
| 10. |
- Deckers, Tobias, et al.
(författare)
-
Impact of processing gas composition on process stability and properties of PBF-LB/M processed alloy 718
- 2024
-
Ingår i: Journal of Manufacturing Processes. - 1526-6125. ; 120, s. 712-718
-
Tidskriftsartikel (refereegranskat)abstract
- The almost unlimited design freedom of the laser-based powder bed fusion of metals (PBF-LB/M) makes this technology very attractive for industry. However, as a developing technology, it still faces some challenges when it comes to productivity and robustness, to name some. Whereas numerous studies covered the impact of laser-based parameters on material properties and robustness, the effect of the processing gas received limited attention. The objective of this study was to evaluate the effect of processing gas composition, containing helium (He) and hydrogen (H2), compared to conventionally used argon (Ar), during PBF-LB/M processing of virgin alloy 718 powder, on printing behavior and part properties. The four gases studied were Ar, Ar +30%He, Ar +30%He +2%H2, and Ar +70%He. Optical Tomography (OT) was used to monitor process stability, which unveiled a significant decrease in process-by products (spatters) between 51 % and 89 % using He and H2-containing gases. It was also found that the process gas decreased the bulk porosity from an average value of 0.08 % when processed with Ar to 0.04 % when using Ar + 70%He. The oxygen pickup by the spatter particles was reduced from 630 ppm (Ar) to 331 ppm (Ar +70%He). EBSD analysis revealed that there were no evident changes in microstructure with the processing gas. The samples processed also had similar tensile properties with yield and ultimate tensile strength of 1180 MPa and 1395 MPa, respectively. However, there was a slight increase in ductility from 16.5 % to 17.2 %, when processed with pure Ar and Ar + 70%He, respectively. This study shows that utilizing standard Ar processing atmosphere with He addition leads to a more stable process with reduced spatter, porosity and a marginal increase in ductility for Alloy 718.
|
|
| 11. |
- Dewi, Handika Sandra, et al.
(författare)
-
Short thermal cycle treatment with laser of vanadium microalloyed steels
- 2020
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 57, s. 543-551
-
Tidskriftsartikel (refereegranskat)abstract
- Improvement of crankshaft fatigue properties can be approached by altering its mechanical properties in the surface, such as laser surface treatment. Laser beam treatment offers efficient and precise surface hardening processing with possibility of reducing the production cost compared to the conventional hardening techniques. However, its characteristic of having short thermal cycle can be a challenge for the development of laser surface hardening techniques, such as inadequacy of literatures in phase transformation and resulting mechanical properties under rapid heating and cooling rate. Therefore, this work investigated the impact of short thermal cycles induced by the laser beam on the resulting microstructure and hardness properties in the surface of 38MnSiVS5 and 44MnSiVS6 microalloyed steels. Temperature cycles during the process were recorded and examined with the resulting microstructure along with microhardness values. 44MnSiVS6 microalloyed steel, which contains ca. double the amount of vanadium compared to 38MnSiVS5 steel, produces finer ferrite grains in the treated area for all investigated short thermal cycles. This fine-grained microstructure leads to steady hardness distributions in the treated area. The short thermal cycle was assumed to be unable to dissolve the vanadium precipitates that reside in the ferrite grains, which then initiate precipitation hardening.
|
|
| 12. |
- Domitner, J., et al.
(författare)
-
Characterization of wear and friction between tool steel and aluminum alloys in sheet forming at room temperature
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 64, s. 774-784
-
Tidskriftsartikel (refereegranskat)abstract
- This work investigates the coefficient of friction (COF) at room temperature between tool steel 1.2343 and aluminum alloys EN AW-5182, EN AW-6016 as-delivered (T4) and EN AW-6016 naturally aged (T4*) using a strip drawing tribometer. In order to simulate the contact conditions of industrial sheet metal forming processes, the surfaces of the steel pins and of the aluminum strips were maintained as-delivered, i.e., the pins were wire-cut from a hardened and ground plate and the strips were cut from electrical discharge textured (EDT) and dry-lubricated sheets. Two sliding velocities, 50 mm/s and 250 mm/s, and two nominal contact pressures, 10 N/mm2 and 20 N/mm2, were considered. The sliding distance on each strip was 0.5 m. Each pair of pins was utilized for testing 10 or 20 strips to study the influence of increasing the sliding distance on the COF. Before and after the tribological experiments, surface topographies of selected pins and strips were analyzed using 3D optical surface profilometry, optical microscopy and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS). Strain hardening due to plastic surface deformation of the strips was investigated using an automated hardness tester. In general, an increasing trend of the COF was observed with increasing sliding distance. The mean COF obtained for each of the tests was in the range of 0.09−0.17; however, it was considerably higher if aluminum was transferred from the strip to the pins. Moreover, moist pin surfaces were identified to increase the COF, as the originally dry lubricant became pasty and sticky which promoted entrapment of abraded aluminum particles. Slightly higher strain hardening of alloy EN AW-5182 compared to alloy EN AW-6016 caused less flattening of the strip asperities and more severe wear of the pin surface.
|
|
| 13. |
- dos Santos Paes, Luiz Eduardo, et al.
(författare)
-
Understanding the behavior of laser surface remelting after directed energy deposition additive manufacturing through comparing the use of iron and Inconel powders
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 70, s. 494-507
-
Tidskriftsartikel (refereegranskat)abstract
- Laser directed energy deposition with powder (pDED-L) is one of the most popular techniques for additive manufacturing. However, for some applications, the resulting surface finish requires post-processing machining. Laser remelting processing has been cited as a means of decreasing machining needs in other applications. The objective of this study was to assess the performance and gain a better physical understanding of the laser remelting process as an alternative to the conventional post-processing techniques applied after pDED-L. pDED-L and remelting were performed using a 10 kW fiber laser source and iron and Inconel 625 powders as feedstock to compare the surface roughness and waviness under different processing conditions (three heat input levels). Through 2D and 3D surface measurements, as well as scanning electron microscopy (SEM), surface features were qualified and quantified. SEM and optical microscopy (OM) were also employed for metallurgical characterization of the roughness. The surface micro-notch effect was assessed through the stress concentration factor (kt). The results indicated attenuation of the average roughness (Ra) by around 30% for iron and 70% for Inconel when laser remelting was employed. In addition, kt presented a 31% reduction for iron and 29% reduction for Inconel. The performance varied according to the type of material used and was mainly related to differences in thermal diffusivity and electrical resistivity. It was concluded that laser remelting is a promising technology for coupling with pDED-L aimed at producing 3D metal components with superior quality while allowing a faster production rate in comparison to current practices.
|
|
| 14. |
- Fischer, Andreas, et al.
(författare)
-
A pragmatic approach for assessment of laser-induced compressive residual stress profiles
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 68, part A, s. 778-787
-
Tidskriftsartikel (refereegranskat)abstract
- Laser hardening is a very efficient technique for local surface treatment, however, in case of complex and large components robust processing is highly challenging due to limitations in terms of the absolute size of the overall heat-affected zone. As is shown in the present work, an increased in-depth effect can be achieved by tailoring the laser parameters without melting the surface layer. Optimization of process parameters leads to an elaborate test design demanding numerous verification measurements to determine essential material properties. In this context, the evaluation of compressive residual stress values in the surface layer is very important, e.g. in case of fatigue loaded components. However, residual stress profile measurements obtained by X-ray diffraction are very time-consuming and, thus, can significantly impair the laser parameter development cycle. For this reason, the present study introduces a novel pragmatic approach allowing for qualitative evaluation of laser-induced compressive residual stress states, in particular for multiple laser pass processes based on a Gaussian-like intensity profile. Based on straightforward analytical evaluation, several characteristic features of the affected surface layer, e.g. the position of the residual stress transition zone, can be correlated to a change of the local energy input. A novel parameter referred to as modified area energy is established in present work for this purpose. This novel energy approach provides for an essential contribution to the field of laser hardening to considerably shorten the experimental effort within the laser parameter search.
|
|
| 15. |
- Fratini, Livan, et al.
(författare)
-
New trends in manufacturing processes research
- 2019
-
Ingår i: JOURNAL OF MANUFACTURING PROCESSES. - : ELSEVIER SCI LTD. - 1526-6125. ; 43, s. 1-1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 16. |
|
|
| 17. |
- Gomez-Gallegos, A. A., 1983-, et al.
(författare)
-
Surface finish control by electrochemical polishing in stainless steel 316 pipes
- 2016
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 23, s. 83-89
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochemical machining (ECM) is a non-conventional machining process which is based on the localised anodic dissolution of any conductive material. One of the main applications of ECM is the polishing of materials with enhanced characteristics, such as high strength, heat-resistance or corrosionresistance, i.e. electrochemical polishing. The present work presents an evaluation of the parameters involved in the ECM of Stainless Steel 316 (SS316) with the objective of predicting the resulting surface finish on the sample. The interest of studying ECM on SS316 resides on the fact that a repeatable surface finish is not easily achieved. ECM experimental tests on SS316 pipes of 1.5 (0.0381 m) diameter were conducted by varying machining parameters such as voltage, interelectrode gap, electrolyte inlet temperature, and electrolyte flow rate. The surface finish of the samples was then evaluated in order to find the significance of each of these parameters on the surface quality of the end product. Results showed that overvoltage, which is dependent on the interelectrode gap and the electrolyte temperature, is one of the main parameters affecting the surface finish; additionally there is a strong relationship between the resulting surface finish and the electrolyte flow. The interelectrode gap and inlet electrolyte temperature also affect the resulting surface finish but their influence was not so evident in this work. Finally, the variation of the electrolyte temperature during the process was found to have a great impact on the uniformity of the surface finish along the sample. We believe that this contribution enables the tailoring of the surface finish to specific applications while reducing manufacturing costs and duration of the ECM process.
|
|
| 18. |
- Grankäll, Tommy, et al.
(författare)
-
The true shape of composite cure tools
- 2020
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier Ltd. - 1526-6125. ; 59, s. 279-286
-
Tidskriftsartikel (refereegranskat)abstract
- The cure tool is a key factor for successful composite part manufacturing since the tool shape is directly reflected in the moulded part. A composite cure tool is an alternative to metal tools. Lead time is often lower and rate tools less expensive. The recurring cost per produced part in the tool is often also lower, for instance from faster autoclave cure time. However, durability is commonly considered less favourable. Beyond all, a composite cure tool is often motivated as being the better option since the thermal expansion is close to that of the part which simplifies compensation of process-induced shape distortion. But is this really accurate? Perhaps, but only if the true mould shape at cure temperature is known. This paper includes both experiments and simulation showing actual composite cure tool shape at cure temperature. Also, simulation of stress levels in the tool laminate indicate an important characteristic of durability.
|
|
| 19. |
- Hauser, Tobias, et al.
(författare)
-
Fluctuation effects in Wire Arc Additive Manufacturing of aluminium analysed by high-speed imaging
- 2020
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 56:Part A, s. 1088-1098
-
Tidskriftsartikel (refereegranskat)abstract
- Wire Arc Additive Manufacturing is a near-net-shape processing technology which allows the cost-effective manufacturing of big and customized metal parts. In the present work the Wire Arc Additive Manufacturing of AW4043/AlSi5(wt.%) with different lead angles of the welding torch was investigated. It has been shown that for some lead angles fluctuation effects occur in the structures produced if the interlayer temperature is either too low or too high. All experiments were analysed by high-speed imaging whereby the welding phenomena could be observed. In the case of Wire Arc Additive Manufacturing with a lead angle above 10° at lower interlayer temperatures, the deposited track consists out of several, seperated WAAM globules and is no longer in a uniform track. In the case of the dragging and neutral Wire Arc Additive Manufacturing processes at higher interlayer temperatures, fluctuation effects occur. In addition, by evaluating the high-speed videos with computer vision, it was found that such fluctuation effects can be detected at the arc frequency of the process. To avoid fluctuation effects caused by too low or too high interlayer temperatures, a pushing Wire Arc Additive Manufacturing process with a slightly tilted lead angle should be used.
|
|
| 20. |
- Hauser, Tobias, et al.
(författare)
-
Multi-Material Wire Arc Additive Manufacturing of low and high alloyed aluminium alloys with in-situ material analysis
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 69, s. 378-390
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, the interest in the improved functionalisation of Additive Manufacturing components through multi-material solutions has increased because of the new possibilities in product design. In this work, an advanced Wire Arc Additive Manufacturing process for fabrication of multi-material structures of different aluminium alloys was investigated. Mechanical properties such as tensile strength, yield strength, fracture elongation, and hardness were analysed for multi-material parts and compared with the mechanical properties of mono-material parts. It was found that the strength of multi-material components was limited by the properties of the individual aluminium alloys and not by those of the material transition zones. Microsections and EDX line scans revealed a smooth transition zone without any significant defects. Furthermore, process monitoring approaches for quality assurance of the correct material composition in such multi-material structures were investigated. Different sensor data were captured during multi-material Wire Arc Additive Manufacturing to identify and observe various characteristics of the process. It was shown that the voltage, current, acoustic, and spectral emission data can be used for in-situ monitoring to detect the chemical differences between the two aluminium alloys 6060 and 5087. Characteristic patterns in the frequency range were found, which can be attributed to a frequency shift that occurred due to the different material properties. Spectral analysis revealed changes in the ratios of green and blue light emission to red light emission, which was also due to the different magnesium contents.
|
|
| 21. |
- Hoier, Philipp, 1988, et al.
(författare)
-
Flank wear characteristics of WC-Co tools when turning Alloy 718 with high-pressure coolant supply
- 2017
-
Ingår i: Journal of Manufacturing Processes. - Dearbord, Mich. : Society of Manufacturing Engineers, North American Manufacturing Research Institution. - 1526-6125 .- 2212-4616. ; 30:Supplement C, s. 116-123
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, the tool wear mechanisms of uncoated cemented tungsten carbide (WC-Co) tools during machining Alloy 718 with high-pressure coolant supply are investigated. Worn flank faces are analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). With increasing spiral cutting length, larger areas on the tool surface are subjected to erosion of Co-binder by the coolant jet impact. Moreover, the amount and morphology of workpiece-precipitates adhered on worn flank surfaces are influenced significantly by the extent of flank wear land (due to increasing spiral cutting length). The reasons for the obtained results are addressed with respect to the underlying mechanisms. Possible implications for the tool wear behavior are discussed.
|
|
| 22. |
- Hoier, Philipp, 1988, et al.
(författare)
-
Influence of batch-to-batch material variations on grindability of a medium‑carbon steel
- 2022
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier Ltd. - 1526-6125. ; 73, s. 463-470
-
Tidskriftsartikel (refereegranskat)abstract
- This study addresses the influence of material variations on the grindability of crankshaft steel. Most previous studies on the effect of material microstructure on grindability involve comparisons of significantly different steel grades. This study, in contrast, is focused on batch-to-batch grindability variations for one steel grade, a scenario frequently occurring in industry where batches from different steel makers are fed into a production line. For this purpose, a batch made of recycled steel and a batch made of ore-based steel were compared with regards to microstructure and grindability under identical grinding and dressing conditions. Although both batches met the same material specifications, microstructural variations were identified in terms of grain size and micro-constituents (inclusions, carbonitrides). While specific grinding energy, residual stress and full-width at half-maximum profiles of ground surfaces were the same for both batches, the recycled batch showed different and unfavorable variation in wheel wear and Barkhausen noise (BN) response. Larger fractions of oxide inclusions and larger grain sizes (affected by carbonitrides) were present in the recycled batch, which were the likely reasons for the differences in wheel wear and BN response, respectively. These findings may aid grindability improvement by steel-grade adjustments, e.g. modification of the distribution and type of inclusions and/or amount of elements forming carbonitrides. Furthermore, the results highlight the importance of understanding and controlling material microstructure, as existing in-line quality by BN control may not always be able to correctly indicate surface integrity, which could lead to misinterpretations (e.g. false part-rejection on the assumption of grinding burn). © 2021 The Authors
|
|
| 23. |
- Holmberg, Jonas, 1976-, et al.
(författare)
-
Selection of milling strategy based on surface integrity investigations of highly deformed Alloy 718 after ceramic and cemented carbide milling
- 2020
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier Ltd. - 1526-6125. ; 58, s. 193-207
-
Tidskriftsartikel (refereegranskat)abstract
- High speed milling with ceramic indexable inserts is a current practice for manufacturing of gas turbine components in superalloys since it allows for high material removal rates. Ceramic milling is used for rough milling, which is followed by cemented carbide semi- and finish milling. The tool motion play an important role on the resulting surface integrity. The machining strategy of up or down milling will induce different degree of residual stresses and deformations. Increased knowledge of selecting the machining strategy with lowest impact will promote improved productivity by using ceramic milling to a greater extent based on the affected depth. The main objective in this work has been to correlate the residual stresses and deformations to promote a greater utilization of ceramic milling while still producing surfaces with acceptable properties. Prior investigations have shown that ceramic milling induce very high tensile stresses in the surface, exceeding the material's nominal yield strength. A second objective has been to explain these stress levels by thorough investigations of the deformation after milling. In this study, milling tests with new and worn ceramic and cemented carbide inserts have been performed in Alloy 718. The topography, residual stresses, deformation and hardness have been investigated for up, centre and down milling. Residual stress measurements were performed using X-ray diffraction, followed by evaluation of hardness and deformation, using hardness testing, light optical microscopy as well as electron back scattering diffraction (EBSD). These results have been used to determine an appropriate milling strategy based on lowest possible impact in respect to residual stresses and deformation. The results show a high degree of deformation after milling that differs for the up, centre and down milling. Based on these results, it is shown that up milling is preferable for new inserts but as the inserts wear out, down milling becomes more suitable since a lower degree of deformation and residual stress impact was observed. EBSD and hardness testing showed that the milling, especially ceramic milling, caused severe deformation of the surfaces resulting in grain refinement to a nano-crystalline level. This is most likely the explanation for the prevalence of the high tensile stresses without distorting or causing failure. © 2020 The Authors
|
|
| 24. |
- Hu, Kaixiong, et al.
(författare)
-
CNN-BiLSTM enabled prediction on molten pool width for thin-walled part fabrication using Laser Directed Energy Deposition
- 2022
-
Ingår i: JOURNAL OF MANUFACTURING PROCESSES. - : Elsevier BV. - 1526-6125. ; 78, s. 32-45
-
Tidskriftsartikel (refereegranskat)abstract
- Laser Directed Energy Deposition (LDED) is a promising metal Additive Manufacturing (AM) technology capable of fabricating thin-walled parts to support some high-value applications. Accurate and efficient prediction on the molten pool width is critical to support in-situ control of LDED for part quality assurance. Nevertheless, owing to the intricate physical mechanisms of the process, it is challenging to designing an effective approach to accomplish the prediction target. To tackle the issue, in this research, a new data model-driven predictive approach, which is enabled by a hybrid machine learning model namely CNN-BiLSTM, is presented. High prediction accuracy and efficiency are achievable through innovative measures in the research, that is, (i) the CNN-BiLSTM model is designed and configured by addressing the characteristics of the LDED process; (ii) process parameters related to the deposition and heat accumulation phenomena during the LDED process are extensively considered to strengthen the prediction accuracy. Experiments for thin-walled part fabrication were conducted to validate and benchmark the approach. In average, 4.286% of the mean absolute percentage error (MAPE) was acquired, and the prediction time took by the approach was only 0.04% of that by a finite element analysis (FEA) approach. Compared to the LSTM model, the BiLSTM model and the CNN-LSTM model, MAPEs of the CNN-BiLSTM model were improved by 27.0%, 17.3% and 12.6%, respectively. It demonstrates that the approach is competent in producing good-quality thin-walled parts using the LDED process.
|
|
| 25. |
- Huang, Hui, et al.
(författare)
-
Experimental and numerical investigation of a gouging heat source model and gouging/welding residual stress and deformation
- 2024
-
Ingår i: Journal of Manufacturing Processes. - 1526-6125. ; 110, s. 101-113
-
Tidskriftsartikel (refereegranskat)abstract
- Gouging is generally used for groove preparation of multi-pass welding and repair welding. Arc gouging is one of the most efficient gouging methods which utilizes an arc heat source and a trailing air blower. To date, the heat effects from the arc gouging are not clear especially when it is coupled with subsequent welding. In this study, a new heat source model considering the blown molten metal as well as the increased heat transfer by the blowing air was proposed. A 3D finite element model for gouging and welding was employed to analyze the thermal behavior, welding distortion and residual stresses. The transient temperature predicted by the proposed heat source model has good agreement with thermocouple measurements, both featuring multiple peaks in the thermal profile. The predicted distortion and residual stress due to gouging show similar trends as those in experiment. The proposed analysis approach can provide necessary insights, with high accuracy, in the evaluation of welding distortion and residual stresses in practical manufacturing.
|
|
| 26. |
- Ji, Wei, et al.
(författare)
-
A study on geometry modelling of a ball-end mill with chamfered cutting edge
- 2015
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 19, s. 205-211
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a geometry modelling approach to cross-section parameters of chamfered cutting edge on a ball-end mill of solid carbide (BEMSC). Both the cutting edge curve and the CR (chamfer in rake face) face models are derived. Based on the CR face model, a new method for CR face grinding path generation is proposed. By determining the relationship between the length and the angle parameters of the CR face equation, its grinding path can be derived. After solving the rake face equation using this method, its grinding path as well as the grinding paths of the LF (land on flank face) face and the second flank face can also be computed. The geometry model has been validated through a series of numerical simulations.
|
|
| 27. |
- Jiangwei, Liu, et al.
(författare)
-
Compressive behavior and vibration-damping properties of porous Ti-6Al-4V alloy manufactured by laser powder bed fusion
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125 .- 2212-4616. ; 66, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- Porous Ti-6Al-4V alloy with various cell geometries and cell sizes was manufactured by laser powder bed fusion (LPBF) technique, and the influence of the structural characteristics on the compressive behavior and vibrationdamping abilities was systematically investigated. In terms of the compressive performance, both elasto-brittle and elasto-plastic features are observed from the compressive stress-strain curves and the corresponding transformation from elasto-brittle to elasto-plastic can be achieved by increasing the cell size. Moreover, the compressive performances are found to be closely related to the relative density determined by both the cell geometries and cell sizes of specimens. The energy absorption capability of each cellular structure increases linearly when increasing the as-manufactured density, while the energy absorption efficiency presents sensitivities to both the cell geometry and the cell size. The results also reveal that the variation of natural frequency is proportional to the specific strength (i.e., strength-weight ratio), and the cellular structure with larger cell size exhibits better damping ability than smaller sized structures.
|
|
| 28. |
- Jin, Lai-Zhe, et al.
(författare)
-
Numerical simulation of residual stresses for friction stir welds in copper canisters
- 2012
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 14:1, s. 71-81
-
Tidskriftsartikel (refereegranskat)abstract
- In an attempt to map the residual stress distributions after friction stir welding of copper canisters, a three-dimensional thermo-mechanical model has been formulated by coupling heat transfer and elastoplasticity analyses. The transient temperature field around the tool is simulated by a moving heat source. The simulation shows that the residual stress distribution in a thick-wall copper canister is sensitive to the circumferential angle and asymmetrical to the weld line. Both tensile and compressive stresses emerge along the weld line and its vicinity. The maximum tensile stress appears in the circumferential direction on the outer surface. The maximum tensile stress, whether it is predicted by the finite element method or measured by the hole-drilling technique and the X-ray diffraction method, does not exceed 50 MPa in general.
|
|
| 29. |
- Jorge, Vinicius Lemes, et al.
(författare)
-
The significance of supplementary shielding in WAAM of aluminium thin walls
- 2023
-
Ingår i: Journal of Manufacturing Processes. - 1526-6125. ; 106, s. 520-536
-
Tidskriftsartikel (refereegranskat)abstract
- WAAM (wire arc additive manufacturing) of aluminium requires special operational care to avoid problems such as instabilities, contamination or porosities. This work aims at verifying whether supplementary shielding gas can affect the WAAM performance when building Al alloy thin walls, in terms of metal transfer, porosity, superficial finishing, and geometrical and metallurgical features. Thin walls were manufactured with and without supplementary shielding (ultra-pure Ar). A dedicated nozzle was designed in-house to provide additional protection against the reaction with surrounding atmospheric gases. Pure Ar and two Ar-based commercial shielding gases with different additives were employed to make the conclusions more sustainable. It was possible to conclude that supplementary shielding leads to better metal transfer regularity, cleaner lateral and surface, a shinier top layer appearance, and a slight trend to higher microhardness. On the other hand, it does not affect porosity after layer depositions, wall geometry (the total and effective layer width, layer height, and surface waviness of the walls), and microstructures. Finally, regarding the performance of shielding gases, there is no evidence of any effect from the supplementary shielding, since this approach improved the process operationality with the three different shielding gases but did not change their individual tendencies.
|
|
| 30. |
- Jorge, Vinicius Lemes, et al.
(författare)
-
Wire feed pulsation as a means of inducing surface tension metal transfer in Gas Metal Arc Welding
- 2021
-
Ingår i: JOURNAL OF MANUFACTURING PROCESSES. - : Elsevier. - 1526-6125. ; 62, s. 655-669
-
Tidskriftsartikel (refereegranskat)abstract
- Gas Metal Arc Welding (GMAW) derivative processes have gained attention due to their capacity to perform specific functions, such as reducing spattering during short-circuiting. However, the short-circuiting transfer nature allows devising other features, such as to work with low current yet with high voltage. Although this arrangement is typical of globular transfer when applied in GMAW, the assistance of wire feed pulsation by itself could make the use of this combination doable. Therefore, this work aimed at exploring the technical feasibility of short-circuiting GMAW with higher voltage level with the aid of a wire feed pulsation technique, rather than relying on current waveform control strategies. In this case, a home-developed device that superimposes a pulsation linear movement to the wire over its continuous movement was employed. To prove the concept, wire pulsation and long arc length during arcing were applied in experiments with the power source operating either in constant voltage or constant current modes. In order to quantify and validate the approach, a range of pulsation frequencies was explored and compared with conditions with continuous feeding. The metal transfer regularity was evaluated following the Laprosolda Metal Transfer Regularity Criterion, and geometric parameters of the weld beads were compared as complement. To assess the metallic transfer behavior, high-speed imaging was also used. A reasoning in terms of arc length was successfully applied to different conditions based on the melting rate equation and misleading voltage usage in short-circuiting for this purpose was demonstrated. The results showed that the wire feed pulsation approach is adequate to improve metal transfer regularity in shortcircuiting GMAW, as long as the power source is set to operate in current constant mode. Furthermore, the actual arc length plays a significant role in the wire feed pulsation process performance.
|
|
| 31. |
- Karlsson, Joakim, 1984-, et al.
(författare)
-
Surface oxidation behavior of Ti-6Al-4V manufactured by Electron Beam Melting (EBM®)
- 2015
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 17, s. 120-126
-
Tidskriftsartikel (refereegranskat)abstract
- Additive manufacturing is an emerging manufacturing technology that enables production of patient specific implants, today primarily out of titanium. For optimal functionality and proper integration between the titanium implant and the body tissues surface properties, such as surface oxide thickness is of particular importance, as it is primarily the surface of the material which interacts with the body. Hence, in this study the surface oxidation behavior of titanium parts manufactured by Electron Beam Melting (EBM®) is investigated using the surface sensitive techniques ToF-SIMS and AES. Oxide thicknesses comparable to those found on conventionally machined surfaces are found by both analysis techniques. However, a build height dependency is discovered for different locations of the EBM® manufactured parts due to the presence of trapped moisture in the machine and temperature gradients in the build.
|
|
| 32. |
- Laakso, Sampsa Vili Antero
(författare)
-
Heat matters when matter heats – The effect of temperature-dependent material properties on metal cutting simulations
- 2017
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 27, s. 261-275
-
Tidskriftsartikel (refereegranskat)abstract
- The goal of metal cutting research is to predict process conditions accurately with a model or a simulation, in order to optimize and develop the processes. Development of such a model requires understanding of multiple branches of physics and engineering such as continuum mechanics, thermodynamics, tribology and materials science. For an accurate model, each aspect of the process must be modelled properly, or at least the effects of a certain phenomenon must be shown to be negligible. This paper investigates the effect of the temperature dependence of material properties on metal cutting simulations for three different engineering materials: AISI 1045 steel, AISI 7075 aluminium and AISI 304 stainless steel. It is generally accepted that the flow stress of metals is dependent on the temperature, but modulus of elasticity, thermal expansion, heat capacity and thermal conductivity are often considered constants and their effect is considered negligible. In this study, orthogonal turning of the materials is simulated with constant material properties and material properties that are functions of temperature. Each material property combination is simulated to test their effect on the results to investigate the individual and interdependent effects. Based on the results, a general guideline can be formed regarding the importance of heat capacity, thermal conductivity, modulus of elasticity and heat transfer.
|
|
| 33. |
- Laakso, Sampsa V.A., et al.
(författare)
-
The mystery of missing feed force — The effect of friction models, flank wear and ploughing on feed force in metal cutting simulations
- 2018
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 33, s. 268-277
-
Tidskriftsartikel (refereegranskat)abstract
- Underestimated feed force is a known systematic error in cutting simulations. It is considered a consequence of inaccurate friction models, but there are indicators that friction is not the only reason for the error. In some cases, the value of Coulomb friction must be over 1.0 to compensate for the feed force and such values cause over-estimated chip thickness for example. In turning, the ploughing force of the tool is affected by the feed velocity, which changes with the work diameter when cutting speed is constant. In addition, the edge geometry of the tool affect the ploughing force. In this paper, friction, edge geometry and the plough force are investigated with experiments and simulations to identify their effect on feed force.
|
|
| 34. |
- Liu, Yang, et al.
(författare)
-
Evolution of residual stress when turning a fillet radius in stainless steel
- 2023
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 85, s. 216-226
-
Tidskriftsartikel (refereegranskat)abstract
- Most studies have been carried out to investigate the surface integrity induced by metal cutting process. However, the previous studies are limited to a longitudinal turning or orthogonal cutting operations and the residual stresses generated in a fillet radius have been ignored. This study uses a combination of experiments and numerical simulations to study the evolution of cutting forces, temperature, chip morphology, and residual stress distributions while turning a fillet radius in AISI 304. Finite Element (FE) models were developed with a Coupled Eulerian and Lagrangian (CEL) method, where the geometric model of the workpiece was established taking into account the previous machined surface profile at the four specific cutting faces. The model was validated by experimental cutting forces, chip morphology, and residual stress profiles. The changing trend of shape and area of uncut chip cross-section during fillet turning were analyzed to explain the evolution of cutting forces and temperatures. The results show that the cutting force components in cutting speed and tangential directions increase during the early stage of the fillet turning process and decrease after that, while the force in the radial direction shows an increasing trend during this process. The maximum temperature at the machined surface is increased along the tool path. In addition, magnitude and depth of residual stress are slightly changed during the fillet radius turning process, but a reduction of the residual stress profile can still be noticed.
|
|
| 35. |
- Liu, Yang, et al.
(författare)
-
Investigation on residual stress evolution in nickel-based alloy affected by multiple cutting operations
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 68, s. 818-833
-
Tidskriftsartikel (refereegranskat)abstract
- Machining-induced residual stresses in a part can significantly influence its performance and service time. It is common that the final surface of the part is produced after multiple cuts in the machining process. In multiple cuts, the previous cuts could often generate accumulated strain/stress and temperature on the part surface. These accumulated strain/stress and temperature will be brought to the subsequent cut or final cut and continuously affect the cutting forces, process temperatures, deformation zones, etc. in subsequent cut, and eventually affect the final residual stresses on the part. This paper reports on a joint experimental and numerical investigation to explore the influence of previous cuts on surface residual stresses with consideration of cutting parameters, cutting procedure, and tool geometries in multiple cut of Inconel 718 alloy. Coupled Eulerian and Lagrangian (CEL) formulation is used in a two/three-cuts numerical model. The loading cycles of the selected material nodes are characterised based on isotropic constitutive model (Johnson-Cook model) to analyse the underlying mechanism of residual stress evolution during cutting sequences. The results show that accumulated stress/strain induced by previous cuts lead to a more curled chip morphology, a slight decrease in cutting force and a slight increase in feed force in the subsequent cut. An increased magnitude and depth of compressive residual stresses in the finished workpiece are generated owing to the influence of previous cuts, and this is more obvious when the previous cut is implemented at a larger uncut chip thickness, using a more negative rake angle or a larger edge radius tool. The residual stress level might be controlled by optimizing the previous cuts to get the desired surface integrity.
|
|
| 36. |
- Mahmoudi, Jafar
(författare)
-
Numerical simulation of the nozzle configuration in strip casting process
- 2022
-
Ingår i: JOURNAL OF MANUFACTURING PROCESSES. - : Elsevier BV. - 1526-6125. ; 77, s. 561-587
-
Tidskriftsartikel (refereegranskat)abstract
- This work examines the design of nozzles in continuous strip casting process. Three-dimensional (3D) simulations of steady turbulent (k-epsilon) flow are done at the upper part of the mould using a finite-volume (CFX) model. This is performed for different inlet systems, including the inlet nozzle jets with a free stream, the submerged nozzle jets, the slot inlet system, and the slot-submerged inlet system. The resulting heat flux to the solidifying shell has also been studied. Numerous operating parameters are examined, including the shape, size, position, and thickness of the ports and the bottom geometry. It is found that different inlet nozzle configurations change the molten flow and heat patterns, mainly in the upper region of the mould. By applying the slot nozzle inlet system, turbulence and values of the averaged velocity field in that area decrease significantly.
|
|
| 37. |
- Naesstroem, Himani, et al.
(författare)
-
Blown powder directed energy deposition on various substrate conditions
- 2022
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 73, s. 660-667
-
Tidskriftsartikel (refereegranskat)abstract
- Blown powder directed energy deposition of SS316L powder is carried out on various substrate surface conditions of SS304 such as cleaned, sand blasted, milled, oily, cold galvanised and painted to study their influence on the process. High-speed imaging is used for process observation and the deposited tracks are analysed qualitatively and quantitatively using surface images, cross sectional macrographs and x-ray images. Frames from high-speed imaging reveal the removal of additional material from the substrate surface such as paint and oil. The stages involved in their removal: peeling and evaporation are presented. EDS analysis showed that no additional elements other than powder and substrate material are found in the track volume. The quantitative results for all specimens show that the surface conditions had minor influences on track width, track height, wetting angle, dilution and deposited cross sectional area. Defects such as porosity, inclusions and cracking were not observed related to the surface conditions. These findings could significantly reduce processing time by skipping the cleaning step before directed energy deposition such as laser cladding or repair in industrial applications.
|
|
| 38. |
- Pocorni, Jetro, 1988-, et al.
(författare)
-
Numerical simulation of laser ablation driven melt waves
- 2017
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 30, s. 303-312
-
Tidskriftsartikel (refereegranskat)abstract
- Numerical simulations on the melt flow down the keyhole front during fibre laser welding are presented here. The calculations confirm the existence of melt waves previously observed by high speed imaging, with velocities ranging between 4-10 m/s. The simulations provide spatial and temporal information on the temperature and flow fields, particularly within the melt film volume, which cannot be observed by high speed imaging. The ablation pressure achieves high values around wave-peaks and at the bottom of the front, just before droplets are sheared off. The simulation results provide explanations on the main liquid transport mechanisms within the keyhole based on information on the temperature, velocity and pressure field and on the geometrical front conditions.
|
|
| 39. |
- Rahmani Dehaghani, Mostafa, et al.
(författare)
-
System identification and closed-loop control of laser hot-wire directed energy deposition using the parameter-signature-quality modeling scheme
- 2024
-
Ingår i: Journal of Manufacturing Processes. - 1526-6125 .- 2212-4616. ; , s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- Hot-wire directed energy deposition using a laser beam (DED-LB/w) is a method of metal additive manufacturing (AM) that has benefits of high material utilization and deposition rate, but parts manufactured by DED-LB/w suffer from a substantial heat input and undesired surface finish. Hence, regulating the process parameters and monitoring the process signatures to control the final quality during the deposition is crucial to ensure the quality of the final part. This paper explores the dynamic modeling of the DED-LB/w process and introduces a parameter-signature-quality modeling and control approach to enhance the quality of modeling and control of part qualities that cannot be measured in situ. The study investigates different process parameters that influence the melt pool width (signature) and bead width (quality) in single and multi-layer beads. The proposed modeling approach utilizes a parameter-signature model as F1 and a signature-quality model as F2. Linear and nonlinear modeling approaches are compared to describe a dynamic relationship between process parameters and a process signature, the melt pool width (F1). A fully connected artificial neural network is employed to model and predict the final part quality, i.e., bead width, based on melt pool signatures (F2). Finally, the effectiveness and usefulness of the proposed parameter-signature-quality modeling is tested and verified by integrating the parameter-signature (F1) and signature-quality (F2) models in the closed-loop control of the width of the part. Compared with the control loop with only F1, the proposed method shows clear advantages and bears potential to be applied to control other part qualities that cannot be directly measured or monitored in situ.
|
|
| 40. |
- Robertson, Stephanie M., et al.
(författare)
-
Material ejection attempts during laser keyhole welding
- 2021
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 67, s. 91-100
-
Tidskriftsartikel (refereegranskat)abstract
- Material loss during keyhole mode laser welding often leads to surface imperfections that can negatively impact component performance. High-speed imaging identified four types of material ejection attempts: classical spatter, re-captured spatter, protuberances, and scalloping. The momentum attributed to the melt body, which is influenced by the keyhole properties, dictates whether the ejection attempt is successful or if the material is re-captured. The relationship between the dynamics of the keyhole and melt pool was elaborated in an extended systematic description of melt ejection attempts, which were then classified. Ejection attempts were often observed to be proceeded by a co-current swelling of the melt, adjacent to the keyhole, followed by a melt depression. The melt swell would elongate into a melt column with a concentration of momentum, where excessive momentum causes the melt to neck and separate into spatter. Trajectory determines if the spatter becomes a permanent fixture or re-incorporates into the melt body, with the latter having the possibility to cause further melt body disturbances leading to more ejection attempts. If the melt column fails to neck and separate, or an additional force acts upon the column, a protuberance or a scallop could then form. Keyhole and melt pool fluctuations were sometimes observed to be accommodated, avoiding material ejection. In these cases, a stable weld could be obtained with large variations in the dimensions of the melt pool and the keyhole.
|
|
| 41. |
- Salame, Charlie, 1996, et al.
(författare)
-
An enhanced semi-analytical estimation of tool-chip interface temperature in metal cutting
- 2023
-
Ingår i: Journal of Manufacturing Processes. - 1526-6125. ; 105, s. 407-430
-
Tidskriftsartikel (refereegranskat)abstract
- An accurate estimation of the temperature distribution on tool surfaces is of great industrial importance; without it, a reliable prediction of tool wear in machining, especially thermally-induced wear mechanisms such as dissolution-diffusion and oxidation, is deemed impossible. This has promoted the development of semi-analytical models for simulation of the tool-chip interface temperature, which are less time-intensive and reasonably accurate. This study aims to present an enhanced prediction of the tool-chip interface temperature within the context of the available semi-analytical solutions of the heat conduction-advection problem with a moving heat source. A novel approach is presented to obtain the variable heat flux along the tool-chip interface based on a non-uniform contribution of generated heat in the sticking and sliding zones during chip flow. The capability of the enhanced model to simulate the temperature distribution is demonstrated for machining C45 and C50 plain carbon steels using uncoated carbide tools. The predictions are validated against the results of experimental orthogonal cutting tests for the same cutting conditions. A comparative analysis is then performed to underline the importance of incorporating the variable heat flux for reliable predictions of the maximum interface temperature and its location on the rake face. The outlook for future developments is also highlighted.
|
|
| 42. |
- Scotti, Fernando Matos, et al.
(författare)
-
Thermal management in WAAM through the CMT Advanced process and an active cooling technique
- 2020
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier Ltd. - 1526-6125. ; 57, s. 23-35
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal management is a key factor in wire + arc additive manufacturing (WAAM) in order to mitigate heat accumulation and cope with limitations regarding deposition cycle, geometry issues, and mechanical property anisotropies. From the process point of view, the variable polarity Cold Metal Transfer process, a variant of the Gas Metal Arc (GMA) deposition process named as CMT Advanced, stands out as a prominent option to reduce the heat transferred to the layers under deposition, without dropping the deposition rate. In another front, thermally managing the component by employing a technique called Near Immersion Active Cooling (NIAC) throughout all the deposition time has shown to be a promising tool to remove heat from the part under construction. Thus, the current work proposes an evaluation of the CMT Advanced process combined with the NIAC technique for WAAM. The deposition of Al alloy wall-like preforms was made by varying the positive and negative polarity ratio (EP/EN) in the CMT Advanced process and the layer edge to water distance (LEWD) in the NIAC technique. Comparative runs were made with natural cooling instead of the NIAC technique. Electric signals and porosity were quantified to verify the constancy of the process. Thermal cycles of a fixed point of the walls and some of their geometrical features were measured to see the effect of the EP/EN and LEWD parameters in terms of thermal management performance. For the deposition circumstances applied, minor lack of coalescence between layers and also adjacent discontinuities appeared in the waviness valleys of the walls. Such occurrences justified optical and scanning electron microscopy examinations at these locations as complement analyses. Even so, the results clearly showed that the EP/EN parameter is more influential in the control of the layer dimensions and of the preform surface waviness. The LEWD parameter has more effect on reducing the heat accumulation and, consequently, assuring no wall widening as the number of deposited layers is increased. Finally, it was inferred that the possibility of affecting the thermal cycles and geometries of the resultant preforms with two independent thermal management tools expands the windows for finding optimal deposition parameters in WAAM. © 2020 The Society of Manufacturing Engineers
|
|
| 43. |
- Shih, A. J., et al.
(författare)
-
Advancements in manufacturing processes
- 2016
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125. ; 24, s. 319-320
-
Tidskriftsartikel (refereegranskat)
|
|
| 44. |
- Silva-Magalhaes, Ana, et al.
(författare)
-
A Friction Stir Welding case study using Temperature Controlled Robotics with a HPDC Cylinder Block and dissimilar materials joining
- 2019
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 46, s. 177-184
-
Tidskriftsartikel (refereegranskat)abstract
- The automotive industry is going through a radical transformation from combustion engines to fully electric propulsion, aiming at improving key performance indicators related to efficiency, environmental sustainability and economic competitiveness. In this transition period, it is important to continue the innovation of combustion engines for e.g. plug-in hybrid vehicles. This led Volvo Cars to pursue radically new manufacturing processes such as Friction Stir Welding (FSW). The work presented in this paper is a case study whereby feasibility of using FSW to join a reinforcement element into the aluminium casted Cylinder Block was studied. The complex geometry of the joint required a flexible five-axis manipulator, i.e. an industrial robot, as well as advanced process control, i.e. temperature feedback control, in order to maintain a consistent weld quality throughout the whole component. The process was successfully demonstrated in a lab environment and offers a cost-efficient solution while maintaining the durability and higher efficiency. The outcome of this study shows the great potential of implementing the FSW process in combination with High Pressure Die Casted components, such a Cylinder Block.
|
|
| 45. |
- Silva-Magalhães, Ana, et al.
(författare)
-
In-situ temperature measurement in friction stir welding of thick section aluminium alloys
- 2019
-
Ingår i: Journal of Manufacturing processes. - : Elsevier. - 1526-6125 .- 2212-4616. ; 39, s. 12-17
-
Tidskriftsartikel (refereegranskat)abstract
- Friction stir welding (FSW) is a reliable joining technology with a wide industrial uptake. However, several fundamentals of the process such as the temperature inside the stirred zone of the weld and its influence on mechanical properties, are not yet fully understood. This paper shows a method for accurate temperature measurements in multiple locations around the tool, to identify the location of the peak temperature, the temperature variations between the advancing and the retreating side of the tool and its relation to the tool geometry. Both standardised thermocouples in the FSW tool and the novel “tool-workpiece thermocouple” method were used to record temperatures.Bead-on-plate welds in 20 mm thickness AA6082-T6 were produced while the temperatures were measured in three locations on the FSW tool: at the shoulder outer diameter, at the transition from shoulder to probe and at the probe tip. It was found that the hottest point in the stirred zone was 607 °C and was located at the transition between the shoulder and probe, on the retreating-trailing side of the tool. The lowest temperature was found at the probe tip on the retreating-leading side of the tool.The results offer a better understanding of the temperature distribution around a FSW tool. The method presented can be applied to verification of thermal simulation models, tool design optimization, quality assurance and temperature feedback control.
|
|
| 46. |
- Singh, Shweta, et al.
(författare)
-
Drilling parameter optimization of cenosphere/HDPE syntactic foam using CO2 laser
- 2022
-
Ingår i: Journal of manufacturing processes. - : Elsevier BV. - 1526-6125. ; 80, s. 28-42
-
Tidskriftsartikel (refereegranskat)abstract
- High-density polyethylene is a high-strength, and low-weight material system. Besides numerous applications in a variety of fields and products, its machining for generation of holes is rather difficult with traditional methods such as drilling as the process is not very conducive for composites due to associated damage. Hence, a non-contact material removal process such as laser machining provides an appealing, cost-effective, accurate, and fast alternative. For this study, the effect of the laser process controls key parameters such as laser power and laser speed on the cut surface integrity defined by surface roughness, kerf taper angle, and heat-affected zone of neat HDPE and HDPE with 60 wt% cenosphere was investigated and optimized using response surface meth-odology. Also, the machining operation was visualized using a Photron FASTCAM SA 1.1 high-speed camera to observe the effects of the high-intensity laser beam on specimens and to investigate the mechanism of laser machining. The optimum values for a defect-free cut surface (minimum surface roughness and low kerf taper angle) in neat HDPE comes out to be as laser power of 97.5 W and laser speed of 5 mm/s, with corresponding surface roughness and kerf taper angle of 54.304 mu m and 0.152 degrees respectively and the optimum input values for HDPE with 60 wt% cenosphere are 102.126 W laser power and 5 mm/s laser speed, with corre-sponding surface roughness and kerf taper angle of 26.574 mu m and 0.253 degrees. This study finds importance for the industrial and medical application to creates small size holes for mechanical joints such as rivets, bolts, and screws in assembly as low surface roughness and kerf width are always preferred as quality parameters in creating holes for industrial applications.
|
|
| 47. |
- Suárez, A., et al.
(författare)
-
Surface integrity and fatigue of non-conventional machined Alloy 718
- 2019
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier Ltd. - 1526-6125 .- 2212-4616. ; 48, s. 44-50
-
Tidskriftsartikel (refereegranskat)abstract
- Alloy 718 is a high-strength, corrosion-resistant nickel chromium-based superalloy frequently used for applications, such as aerospace, marine, nuclear reactor and chemical industries, due to its outstanding inherent properties such as high strength and corrosion resistance at high temperatures together with good creep behaviour. Although, the use of conventional manufacturing processes is prevalent for their use on Alloy 718, alternative manufacturing technologies are gaining importance. This work compares the effects of alternative manufacturing processes, such as Abrasive water jet (AWJ), Wire Electrical Discharge Machining (WEDM) and ultrasound vibration assisted milling (UVAM) with conventional milling during the manufacture of Alloy 718 parts. Surface integrity, hardness, residual stress and fatigue strength obtained from these machining processes have been examined for cutting alloy 718. Results show that both residual stresses and surface roughness are correlated with fatigue strength. UVAM results shown an improvement on the surface integrity of the final workpiece. AWJ and WEDM show poorer results, further work on post-process technologies or process condition selection must be carry out to establish them as an alternative in Alloy 718 cutting operations.
|
|
| 48. |
- Tamil Alagan, Nageswaran, 1990-, et al.
(författare)
-
Investigation of micro-textured cutting tools used for face turning of alloy 718 with high-pressure cooling
- 2019
-
Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125 .- 2212-4616. ; 37, s. 606-616
-
Tidskriftsartikel (refereegranskat)abstract
- There is an increasing demand to improve the service life of cutting tools during machining of heat resistant superalloys (HRSA). Various studies showed that textured cutting tools improved the tribological properties and reduced cutting forces, temperature, and tool wear. Surface texturing can be seen as a futuristic design to improve the performance of the cutting tool and to increase productivity. However, only limited research has been conducted in machining superalloys with textured inserts and high-pressure coolant. In this work, three different micro texture designs on both rake and flank face are investigated in combination with high-pressure coolant in machining Alloy 718. Due to better tool life predictability, carbide cutting tools are used in machining components made from superalloys. However, the disadvantage is that machining can only be done at lower cutting speed/feed rate/depth of cut with high tool wear rates. The experimental investigation using different tool wear analysis methods showed that the combination of a cylindrical dimple on the rake and the square pyramid texture on the flank surface improved the wear resistance of the tool. An increase in tool life of about 30% was achieved as compared with a regular insert for the investigated cutting conditions. Different levels of adhering workpiece material were observed on the rake face of textured tools. Furthermore, the chip backside showed imprints from the tool textures. The tool textures on the rake face have influenced the tool-chip friction conditions during cutting.
|
|
| 49. |
|
|
| 50. |
|
|
