Journal of Manufacturing and Materials Processing

13 pages, 3753 KiB

Open AccessArticle

Hybrid Manufacturing of Stiffening Grooves in Additive Deposited Thin Parts

by Valentino A. M. Cristino, João P. M. Pragana, Ivo M. F. Bragança, Carlos M. A. Silva and Paulo A. F. Martins

J. Manuf. Mater. Process. 2021, 5(4), 140; https://doi.org/10.3390/jmmp5040140 - 20 Dec 2021

Cited by 3 | Viewed by 3235

Abstract

This paper is focused on the hybridization of additive manufacturing with single-point incremental forming to produce stiffening grooves in thin metal parts. An analytical model built upon in-plane stretching of a membrane is provided to determine the tool force as a function of [...] Read more.

This paper is focused on the hybridization of additive manufacturing with single-point incremental forming to produce stiffening grooves in thin metal parts. An analytical model built upon in-plane stretching of a membrane is provided to determine the tool force as a function of the required groove depth and to estimate the maximum allowable groove depth that can be formed without tearing. The results for additively deposited stainless-steel sheets show that the proposed analytical model can replicate incremental plastic deformation of the stiffening grooves in good agreement with experimental observations and measurements. Anisotropy and lower formability caused by the dendritic-based microstructure of the additively deposited stainless-steel sheets justifies the reason why the maximum allowable depth of the stiffening grooves is approximately 27% smaller than that obtained for the wrought commercial sheets of the same material that are used for comparison purposes. Full article

(This article belongs to the Topic Additive Manufacturing)

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19 pages, 9314 KiB

Open AccessArticle

Local Shielding Gas Supply in Remote Laser Beam Welding

by Klaus Schricker, Andreas Baumann and Jean Pierre Bergmann

J. Manuf. Mater. Process. 2021, 5(4), 139; https://doi.org/10.3390/jmmp5040139 - 17 Dec 2021

Cited by 1 | Viewed by 3092

Abstract

The use of shielding gases in laser beam welding is of particular interest for materials interacting with ambient oxygen, e.g., copper, titanium or high-alloy steels. These materials are often processed by remote laser beam welding where short welds (e.g., up to 40 mm [...] Read more.

The use of shielding gases in laser beam welding is of particular interest for materials interacting with ambient oxygen, e.g., copper, titanium or high-alloy steels. These materials are often processed by remote laser beam welding where short welds (e.g., up to 40 mm seam length) are commonly used. Such setups prevent gas nozzles from being carried along on the optics due to the scanner application and a small area needs to be served locally with inert gas. The article provides systematic investigations into the interaction of laser beam processes and parameters of inert gas supply based on a modular flat jet nozzle. Based on the characterization of the developed nozzle by means of high-speed Schlieren imaging and constant temperature anemometry, investigations with heat conduction welding and deep penetration welding were performed. Bead-on-plate welds were carried out on stainless steel AISI 304 for this purpose using a disc laser and a remote welding system. Argon was used as shielding gas. The interaction between Reynolds number, geometrical parameters and welding/flow direction was considered. The findings were proved by transferring the results to a complex weld seam geometry (C-shape). Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques)

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12 pages, 3973 KiB

Open AccessArticle

Residual Stresses Control in Additive Manufacturing

by Xufei Lu, Miguel Cervera, Michele Chiumenti and Xin Lin

J. Manuf. Mater. Process. 2021, 5(4), 138; https://doi.org/10.3390/jmmp5040138 - 16 Dec 2021

Cited by 33 | Viewed by 5687

Abstract

Residual stresses are one of the primary causes for the failure of parts or systems in metal additive manufacturing (AM), since they easily induce crack propagation and structural distortion. Although the formation of residual stresses has been extensively studied, the core factors steering [...] Read more.

Residual stresses are one of the primary causes for the failure of parts or systems in metal additive manufacturing (AM), since they easily induce crack propagation and structural distortion. Although the formation of residual stresses has been extensively studied, the core factors steering their development in AM have not been completely uncovered. To date, several strategies based on reducing the thermal gradients have been developed to mitigate the manifestation of residual stresses in AM; however, how to choose the optimal processing plan is still unclear for AM designers. In this regard, the concept of the yield temperature, related to the thermal deformation and the mechanical constraint, plays a crucial role for controlling the residual stresses, but it has not been duly investigated, and the corresponding approach to control stresses is also yet lacking. To undertake such study, a three-bar model is firstly used to illustrate the formation mechanism of the residual stress and its key causes. Next, an experimentally calibrated thermomechanical finite element model is used to analyze the sensitivity of the residual stresses to the scan pattern, preheating, energy density, and the part geometry and size, as well as the substrate constraints. Based on the numerical results obtained from this analysis, recommendations on how to minimize the residual stresses during the AM process are provided. Full article

(This article belongs to the Topic Additive Manufacturing)

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DED process: (a) in situ experimental set-up; (b) scanning path used; (c) locations of two thermocouples (TC1-TC2) and one displacement sensor (DS) at the bottom surface of the substrate. Full article ">Figure 2
FE mesh models: (a) 40-layer rectangular block; (b) 4-layer rectangular block; (c) 4-layer square block. The lines AB and EF at the build-substrate interface are used to analyze the residual stresses while the lines CD and GH at the deposit top are used to analyze the displacement of DED parts. Full article ">Figure 3
Comparison between simulated and measured thermo-mechanical results of the block. Full article ">Figure 4
The formation of residual stresses in welding and AM processes. Full article ">Figure 5
Rectangular block: (a) scan patterns; (b) temperature and (c) von Mises stress during the deposition of the 2nd layer; (d) residual stresses; (e) final distortions (displacements norm); (f) residual von Mises stresses along the AB line at the baseplate top; (g) final vertical displacements along the CD line at the deposit top. Full article ">Figure 6
Contour-fills of residual von Mises stresses and the vertical displacements for different AM processes: preheating (a) the whole substrate to 500 °C and (b) the deposit region on the substrate surface by laser (transverse scan); increasing the deposit height to (c) 4 mm and (d) 6 mm, respectively; using the (e) lower and (f) higher energy to fabricate AM block, respectively; (g) residual von Mises stresses along the AB line at the substrate top; (h) vertical displacements along the CD line at the deposit top. Full article ">Figure 7
Square block: (a) different substrate designs; (b) von Mises stress field; (c) final distortions (displacements norm); (d) residual von Mises stresses along the EF line at the baseplate top; (e) vertical displacements along the GH line at the deposit top. Full article ">

15 pages, 2694 KiB

Open AccessArticle

A Study of the Convective Cooling of Large Industrial Billets

by Richard Turner

J. Manuf. Mater. Process. 2021, 5(4), 137; https://doi.org/10.3390/jmmp5040137 - 16 Dec 2021

Viewed by 2947

Abstract

The thermodynamic heat-transfer mechanisms, which occur as a heated billet cools in an air environment, are of clear importance in determining the rate at which a heated billet cools. However, in finite element modelling simulations, the convective heat transfer term of the heat [...] Read more.

The thermodynamic heat-transfer mechanisms, which occur as a heated billet cools in an air environment, are of clear importance in determining the rate at which a heated billet cools. However, in finite element modelling simulations, the convective heat transfer term of the heat transfer mechanisms is often reduced to simplified or guessed constants, whereas thermal conductivity and radiative emissivity are entered as detailed temperature dependent functions. As such, in both natural and forced convection environments, the fundamental physical relationships for the Nusselt number, Reynolds number, Raleigh parameter, and Grashof parameter were consulted and combined to form a fundamental relationship for the natural convective heat transfer as a temperature-dependent function. This function was calculated using values for air as found in the literature. These functions were then applied within an FE framework for a simple billet cooling model, compared against FE predictions with constant convective coefficient, and further compared with experimental data for a real steel billet cooling. The modified, temperature-dependent convective transfer coefficient displayed an improved prediction of the cooling curves in the majority of experiments, although on occasion a constant value model also produced very similar predicted cooling curves. Finally, a grain growth kinetics numerical model was implemented in order to predict how different convective models influence grain size and, as such, mechanical properties. The resulting findings could offer improved cooling rate predictions for all types of FE models for metal forming and heat treatment operations. Full article

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14 pages, 3502 KiB

Open AccessArticle

Laser Welding of AISI 316L Stainless Steel Produced by Additive Manufacturing or by Conventional Processes

by Morgane Mokhtari, Pierrick Pommier, Yannick Balcaen and Joel Alexis

J. Manuf. Mater. Process. 2021, 5(4), 136; https://doi.org/10.3390/jmmp5040136 - 14 Dec 2021

Cited by 21 | Viewed by 5118

Abstract

Among all the additive manufacturing techniques, Laser Powder Bed Fusion (LBPF), also called Selective Laser Melting (SLM), is the most common technique due to its high capability of building complex parts with generally improved mechanical properties. One of the main drawbacks of this [...] Read more.

Among all the additive manufacturing techniques, Laser Powder Bed Fusion (LBPF), also called Selective Laser Melting (SLM), is the most common technique due to its high capability of building complex parts with generally improved mechanical properties. One of the main drawbacks of this technique is the sample size limitation, which depends on elaborating chamber dimensions. In this study, we investigate the viability of obtaining large parts with the laser welding of additive manufactured plates. A comparison of the microstructure and the tensile mechanical properties of SLM-welded plates and cold-rolled welded plates was performed. This paper shows the possibility of obtaining defect-free parts. Even if welding has a low impact on the microstructure of the SLM samples, fractures are located on the fusion zone, and a decrease in ductility of around 30% compared to the base metal is observed. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques)

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(a) Experimental welding setup. (b) Standard geometrical specifications described in EN ISO 6947. Full article ">Figure 2
Radiography of the worst seam parts for the CR sample and SLM samples, respectively. Full article ">Figure 3
Welded cold-rolled sheets: macrography of the weld seam (a); higher magnification of base metal (BM) (b); fusion zone—heat-affected zone (HAZ) boundary (d,e) and fusion zone (FZ) (c); welded SLM sheets: macrography of the weld seam (f); higher magnification of base metal (BM) (g); fusion zone—heat-affected zone (HAZ) boundary (i–k) and fusion zone (FZ) (h). Dashed lines correspond to fusion zone boundaries. Dotted lines correspond to melt pool boundaries. Red dots correspond to SEM-EDX point analysis positions. Full article ">Figure 4
(a) (Left) SEM-EBSD inverse pole figure (IPF) X cross-section map of welded CR; (middle) phase map of the heat-affect area (HAZ) and SEM-EBSD inverse pole figure (IPF) X top map of welded CR (right). (b) SEM-EBSD inverse pole figure (IPF) X maps of cross-section welded SLM (left), base metal SLM (middle), and top welded SLM (right), respectively. Black lines correspond to random grain boundaries and red lines to Σ3 twin grain boundaries (GB). Full article ">Figure 5
Pole figures of the crystallographic planes (001), (011), and (111) for the fusion zone and base metal of a welded cold-rolled sheet (a) and a welded SLM sheet (b), respectively. Full article ">Figure 6
Cross-section hardness evolution of welded samples. Dashed lines correspond to the limit of the fusion zone. Full article ">Figure 7
Stress–strain tensile curves of reference and welded samples. Reference samples corresponds to non-welded samples. (Right) Evolution of axial strain difference between Fusion Zone (FZ) and Base Metal (BM) with the global strain. Full article ">

14 pages, 4816 KiB

Open AccessArticle

Detecting Process Anomalies in the GMAW Process by Acoustic Sensing with a Convolutional Neural Network (CNN) for Classification

by Maximilian Rohe, Benedict Niklas Stoll, Jörg Hildebrand, Jan Reimann and Jean Pierre Bergmann

J. Manuf. Mater. Process. 2021, 5(4), 135; https://doi.org/10.3390/jmmp5040135 - 11 Dec 2021

Cited by 18 | Viewed by 3719

Abstract

Today, the quality of welded seams is often examined off-line with either destructive or non-destructive testing. These test procedures are time-consuming and therefore costly. This is especially true if the welds are not welded accurately due to process anomalies. In manual welding, experienced [...] Read more.

Today, the quality of welded seams is often examined off-line with either destructive or non-destructive testing. These test procedures are time-consuming and therefore costly. This is especially true if the welds are not welded accurately due to process anomalies. In manual welding, experienced welders are able to detect process anomalies by listening to the sound of the welding process. In this paper, an approach to transfer the “hearing” of an experienced welder into an automated testing process is presented. An acoustic measuring device for recording audible sound is installed for this purpose on a fully automated welding fixture. The processing of the sound information by means of machine learning methods enables in-line process control. Existing research results until now show that the arc is the main sound source. However, both the outflow of the shielding gas and the wire feed emit sound information. Other investigations describe welding irregularities by evaluating and assessing existing sound recordings. Descriptive analysis was performed to find a connection between certain sound patterns and welding irregularities. Recent contributions have used machine learning to identify the degree of welding penetration. The basic assumption of the presented investigations is that process anomalies are the cause of welding irregularities. The focus was on detecting deviating shielding gas flow rates based on audio recordings, processed by a convolutional neural network (CNN). After adjusting the hyperparameters of the CNN it was capable of distinguishing between different flow rates of shielding gas. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques)

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14 pages, 8848 KiB

Open AccessArticle

Development of a Multidirectional Wire Arc Additive Manufacturing (WAAM) Process with Pure Object Manipulation: Process Introduction and First Prototypes

by Khushal Parmar, Lukas Oster, Samuel Mann, Rahul Sharma, Uwe Reisgen, Markus Schmitz, Thomas Nowicki, Jan Wiartalla, Mathias Hüsing and Burkhard Corves

J. Manuf. Mater. Process. 2021, 5(4), 134; https://doi.org/10.3390/jmmp5040134 - 10 Dec 2021

Cited by 9 | Viewed by 4482

Abstract

Wire Arc Additive Manufacturing (WAAM) with eccentric wire feed requires defined operating conditions due to the possibility of varying shapes of the deposited and solidified material depending on the welding torch orientation. In consequence, the produced component can contain significant errors because single [...] Read more.

Wire Arc Additive Manufacturing (WAAM) with eccentric wire feed requires defined operating conditions due to the possibility of varying shapes of the deposited and solidified material depending on the welding torch orientation. In consequence, the produced component can contain significant errors because single bead geometrical errors are cumulatively added to the next layer during a building process. In order to minimise such inaccuracies caused by torch manipulation, this article illustrates the concept and testing of object-manipulated WAAM by incorporating robotic and welding technologies. As the first step towards this target, robotic hardware and software interfaces were developed to control the robot. Alongside, a fixture for holding the substrate plate was designed and fabricated. After establishing the robotic setup, in order to complete the whole WAAM process setup, a Gas Metal Arc Welding (GMAW) process was built and integrated into the system. Later, an experimental plan was prepared to perform single and multilayer welding experiments as well as for different trajectories. According to this plan, several welding experiments were performed to decide the parametric working range for the further WAAM experiments. In the end, the results of the first multilayer depositions over intricate trajectories are shown. Further performance and quality optimization strategies are also discussed at the end of this article. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques)

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3 pages, 176 KiB

Open AccessEditorial

Impulse-Based Manufacturing Technologies

by Verena Psyk

J. Manuf. Mater. Process. 2021, 5(4), 133; https://doi.org/10.3390/jmmp5040133 - 9 Dec 2021

Viewed by 2082

Abstract

Modern manufacturing faces extensive technological and economic challenges to remain competitive under the current political and social conditions [...] Full article

(This article belongs to the Special Issue Impulse-Based Manufacturing Technologies)

23 pages, 5299 KiB

Open AccessArticle

Overmolding of Hybrid Long and Short Carbon Fiber Polypropylene Composite: Optimizing Processing Parameters

by Cahyo Budiyantoro, Heru S. B. Rochardjo and Gesang Nugroho

J. Manuf. Mater. Process. 2021, 5(4), 132; https://doi.org/10.3390/jmmp5040132 - 8 Dec 2021

Cited by 4 | Viewed by 3662

Abstract

Injection overmolding was used to produce hybrid unidirectional continuous-short carbon fiber reinforced polypropylene. Polypropylene pellets containing short carbon fibers were melted and overmolded on unidirectional carbon fibers, which act as the core of the composite structure. Four factors were varied in this study: [...] Read more.

Injection overmolding was used to produce hybrid unidirectional continuous-short carbon fiber reinforced polypropylene. Polypropylene pellets containing short carbon fibers were melted and overmolded on unidirectional carbon fibers, which act as the core of the composite structure. Four factors were varied in this study: fiber pretension applied to unidirectional fibers, injection pressure, melting temperature, and backpressure used for melting and injecting the composite pellet. This study aimed to evaluate the effect of these factors on fiber volume fraction, flexural strength, and impact strength of the hybrid composite. The relationship between factors and responses was analyzed using Box–Behnken Response Surface Methodology (RSM) and analysis of variance (ANOVA). Each aspect was divided into three levels. There were 27 experimental runs carried out, with three replicated center points. The results showed that the injection molding process parameters had no significant effect on the fiber’s volume fraction. On the other hand, melting temperature and fiber pretension significantly affected impact strength and flexural strength. Full article

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13 pages, 3501 KiB

Open AccessCommunication

Prediction and Compensation of Color Deviation by Response Surface Methodology for PolyJet 3D Printing

by Xingjian Wei, Abhinav Bhardwaj, Li Zeng and Zhijian Pei

J. Manuf. Mater. Process. 2021, 5(4), 131; https://doi.org/10.3390/jmmp5040131 - 4 Dec 2021

Cited by 8 | Viewed by 3762

Abstract

PolyJet 3D printing can produce any color by mixing multiple materials. However, there are often large deviations between the measured color of printed samples and the target color (when the target color is used as the specified color in the printer software). Therefore, [...] Read more.

PolyJet 3D printing can produce any color by mixing multiple materials. However, there are often large deviations between the measured color of printed samples and the target color (when the target color is used as the specified color in the printer software). Therefore, to achieve a target color on a printed sample, the specified color in the printer software should not be the same as the target color. This study applies response surface methodology (RSM) to determine the optimal color specification to compensate for color deviations of the measured color of printed samples from the target color in PolyJet 3D printing. The RSM has three steps. First, a set of experiments are designed for a target color according to central composite design. Second, the experimental data are used to develop a second-order multivariate multiple regression model to predict the deviation between the measured color and the target color. Third, the optimal color specification (often different from the target color) is determined by using the developed predictive model and the desirability function. When the optimal color specification is used as the specified color in the printer software, the deviation between the predicted color of the printed sample and the target color is minimized. The proposed method is applied to four target colors to demonstrate its effectiveness. The results show that the proposed method performs better than the conventional color specification method without compensation in achieving the four target colors by 33% on average. Full article

(This article belongs to the Topic Additive Manufacturing)

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16 pages, 6074 KiB

Open AccessArticle

Investigation of Gyroscopic Effect on the Stability of High Speed Micromilling via Bifurcation Analysis

by Rinku K. Mittal and Ramesh K. Singh

J. Manuf. Mater. Process. 2021, 5(4), 130; https://doi.org/10.3390/jmmp5040130 - 2 Dec 2021

Cited by 3 | Viewed by 2638

Abstract

Catastrophic tool failure due to the low flexural stiffness of the micro-tool is a major concern for micromanufacturing industries. This issue can be addressed using high rotational speed, but the gyroscopic couple becomes prominent at high rotational speeds for micro-tools affecting the dynamic [...] Read more.

Catastrophic tool failure due to the low flexural stiffness of the micro-tool is a major concern for micromanufacturing industries. This issue can be addressed using high rotational speed, but the gyroscopic couple becomes prominent at high rotational speeds for micro-tools affecting the dynamic stability of the process. This study uses the multiple degrees of freedom (MDOF) model of the cutting tool to investigate the gyroscopic effect in machining. Hopf bifurcation theory is used to understand the long-term dynamic behavior of the system. A numerical scheme based on the linear multistep method is used to solve the time-periodic delay differential equations. The stability limits have been predicted as a function of the spindle speed. Higher tool deflections occur at higher spindle speeds. Stability lobe diagram shows the conservative limits at high rotational speeds for the MDOF model. The predicted stability limits show good agreement with the experimental limits, especially at high rotational speeds. Full article

(This article belongs to the Special Issue Advances in Modelling of Machining Operations)

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22 pages, 1252 KiB

Open AccessArticle

Development of a Cost Model for Vertical Milling Machines to Assess Impact of Lightweighting

by Matthew J. Triebe, Fu Zhao and John W. Sutherland

J. Manuf. Mater. Process. 2021, 5(4), 129; https://doi.org/10.3390/jmmp5040129 - 1 Dec 2021

Viewed by 3760

Abstract

Lightweighting is a design strategy to reduce energy consumption through the reduction of mass of a product. Lightweighting can be applied to machine tools to reduce the amount of energy consumed during the use phase. Thus, the energy cost of machine operation will [...] Read more.

Lightweighting is a design strategy to reduce energy consumption through the reduction of mass of a product. Lightweighting can be applied to machine tools to reduce the amount of energy consumed during the use phase. Thus, the energy cost of machine operation will be reduced. One might also hypothesize that since a lighter-weight machine tool requires less material to build, the cost to produce such a machine will be less. However, it may also be the case that lightweighting a machine tool increases its complexity, which will likely drive up the cost to manufacture the machine. To explore the cost drivers associated with building a machine tool, data on the features associated with a wide variety of vertical milling machine tools are collected. Then, empirical cost models are fit to this data. The results from the cost models show that the machine tool mass is a significant cost driver; other key drivers are the number of axes and spindle power. The models are used to predict the cost benefits of lightweighting in terms of mass, which are compared to potential increased manufacturing costs associated with complexities introduced due to lightweighting. Full article

(This article belongs to the Special Issue Advances in Multi-Axis Machining)

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14 pages, 4776 KiB

Open AccessArticle

A Multiaxis Tool Path Generation Approach for Thin Wall Structures Made with WAAM

by Matthieu Rauch, Jean-Yves Hascoet and Vincent Querard

J. Manuf. Mater. Process. 2021, 5(4), 128; https://doi.org/10.3390/jmmp5040128 - 30 Nov 2021

Cited by 17 | Viewed by 5040

Abstract

Wire Arc Additive Manufacturing (WAAM) has emerged over the last decade and is dedicated to the realization of high-dimensional parts in various metallic materials. The usual process implementation consists in associating a high-performance welding generator as heat source, a NC controlled 6 or [...] Read more.

Wire Arc Additive Manufacturing (WAAM) has emerged over the last decade and is dedicated to the realization of high-dimensional parts in various metallic materials. The usual process implementation consists in associating a high-performance welding generator as heat source, a NC controlled 6 or 8 degrees (for example) of freedom robotic arm as motion system and welding wire as feedstock. WAAM toolpath generation methods, although process specific, can be based on similar approaches developed for other processes, such as machining, to integrate the process data into a consistent technical data environment. This paper proposes a generic multiaxis tool path generation approach for thin wall structures made with WAAM. At first, the current technological and scientific challenges associated to CAD/CAM/CNC data chains for WAAM applications are introduced. The focus is on process planning aspects such as non-planar non-parallel slicing approaches and part orientation into the working space, and these are integrated in the proposed method. The interest of variable torch orientation control for complex shapes is proposed, and then, a new intersection crossing tool path method based on Design For Additive Manufacturing considerations is detailed. Eventually, two industrial use cases are introduced to highlight the interest of this approach for realizing large components. Full article

(This article belongs to the Special Issue Advances in Multi-Axis Machining)

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13 pages, 4513 KiB

Open AccessArticle

High-Precision Adjustment of Welding Depth during Laser Micro Welding of Copper Using Superpositioned Spatial and Temporal Power Modulation

by Marc Hummel, André Häusler and Arnold Gillner

J. Manuf. Mater. Process. 2021, 5(4), 127; https://doi.org/10.3390/jmmp5040127 - 25 Nov 2021

Cited by 8 | Viewed by 3728

Abstract

For joining metallic materials for battery applications such as copper and stainless steel, laser beam micro welding with beam sources in the near-infrared range has become established in recent years. In laser beam micro welding, spatial power modulation describes the superposition of the [...] Read more.

For joining metallic materials for battery applications such as copper and stainless steel, laser beam micro welding with beam sources in the near-infrared range has become established in recent years. In laser beam micro welding, spatial power modulation describes the superposition of the linear feed motion with an oscillating motion. This modulation method serves to widen the cross-section of the weld seam as well as to increase the process stability. Temporal power modulation refers to the controlled modulation of the laser power over time during the welding process. In this paper, the superposition of both temporal and spatial power modulation methods is presented, which enables a variable control of the weld penetration depth. Three weld geometries transverse to the feed direction are part of this investigation: the compensation of the weld penetration depth due to the asymmetric path movement during spatial power modulation only, a W-shaped weld profile, and a V-shaped. The weld geometries are investigated by the bed on plate weld tests with CuSn6. Furthermore, the use of combined power modulation for welding tests in butt joint configuration between CuSn6 and stainless steel 1.4301 with different material properties is investigated. The study shows the possibility of precise control of the welding depth by this methodology. Depending on the material combination, the desired regions with maximum and minimum welding depth can be achieved by the control of local and temporal power modulation on the material surface. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques)

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18 pages, 6913 KiB

Open AccessArticle

FE-Simulation Based Design of Wear-Optimized Cutting Edge Roundings

by Benjamin Bergmann, Berend Denkena, Sascha Beblein and Tobias Picker

J. Manuf. Mater. Process. 2021, 5(4), 126; https://doi.org/10.3390/jmmp5040126 - 25 Nov 2021

Cited by 6 | Viewed by 3277

Abstract

The performance of cutting tools can be significantly enhanced by matching the cutting edge rounding to the process and material properties. However, the conventional cutting edge rounding design is characterized by a significant number of experimental machining studies, which involve considerable cost, time, [...] Read more.

The performance of cutting tools can be significantly enhanced by matching the cutting edge rounding to the process and material properties. However, the conventional cutting edge rounding design is characterized by a significant number of experimental machining studies, which involve considerable cost, time, and resources. In this study, a novel approach to cutting edge rounding design using FEM-based chip formation simulations is presented. Based on a parameterized simulation model, tool temperatures, stresses and relative velocities can be calculated as a function of tool microgeometry. It can be shown that the external tool loads can be simulated with high agreement. With the help of these loads and the use of wear models, the resulting tool wear and the optimum cutting edge rounding can be determined. The final experimental investigations show a qualitatively high agreement to the simulation, which will enable a reduced effort design of the cutting edge in the future. Full article

(This article belongs to the Topic Modern Technologies and Manufacturing Systems)

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18 pages, 8276 KiB

Open AccessArticle

Micro-Milling Process of Metals: A Comparison between Femtosecond Laser and EDM Techniques

by Luigi Calabrese, Martina Azzolini, Federico Bassi, Enrico Gallus, Sara Bocchi, Giancarlo Maccarini, Giuseppe Pellegrini and Chiara Ravasio

J. Manuf. Mater. Process. 2021, 5(4), 125; https://doi.org/10.3390/jmmp5040125 - 22 Nov 2021

Cited by 9 | Viewed by 3624

Abstract

Nowadays, micro-machining techniques are commonly used in several industrial fields, such as automotive, aerospace and medical. Different technologies are available, and the choice must be made considering many factors, such as the type of machining, the number of lots and the required accuracy [...] Read more.

Nowadays, micro-machining techniques are commonly used in several industrial fields, such as automotive, aerospace and medical. Different technologies are available, and the choice must be made considering many factors, such as the type of machining, the number of lots and the required accuracy specifications in terms of geometrical tolerances and surface finish. Lasers and electric discharge machining (EDM) are widely used to produce micro-components and are similarly unconventional thermal technologies. In general, a laser is particularly appreciated by the industry for the excellent machining speeds and for the possibility to machine essentially any type of materials. EDM, on the other hand, has a poor material removal rate (MRR) but can produce microparts on only electrically conductive workpieces, reaching high geometrical accuracy and realizing steep walls. The most common micro-application for both the technologies is drilling but they can make also milling operations. In this work, a comparison of femto-laser and EDM technologies was made focusing on micro-milling. Two features were selected to make the comparison: micro-channels and micro-pillars. The depth was varied on two levels for both features. As workpiece material, aluminum, stainless steel and titanium alloy were tested. Data regarding the process performance and the geometrical characteristics of the features were analyzed. The results obtained with the two technologies were compared. This work improves the knowledge of the micro-manufacturing processes and can help in the characterization of their capabilities. Full article

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13 pages, 4201 KiB

Open AccessCommunication

Evaluating Temperature Control in Friction Stir Welding for Industrial Applications

by Arnold Wright, Troy R. Munro and Yuri Hovanski

J. Manuf. Mater. Process. 2021, 5(4), 124; https://doi.org/10.3390/jmmp5040124 - 19 Nov 2021

Cited by 11 | Viewed by 3582

Abstract

Reports in the literature indicate that temperature control in Friction Stir Welding (FSW) enables better weld properties and easier weld process development. However, although methods of temperature control have existed for almost two decades, industry adoption remains limited. This work examines single-loop Proportional-Integral-Derivative [...] Read more.

Reports in the literature indicate that temperature control in Friction Stir Welding (FSW) enables better weld properties and easier weld process development. However, although methods of temperature control have existed for almost two decades, industry adoption remains limited. This work examines single-loop Proportional-Integral-Derivative (PID) control on spindle speed as a comparatively simple and cost-effective method of adding temperature control to existing FSW machines. Implementation of PID-based temperature control compared to uncontrolled FSW in AA6111 at linear weld speeds of 1–2 m per minute showed improved mechanical properties and greater consistency in properties along the length of the weld under temperature control. Additionally, results indicate that a minimum spindle rpm may exist, above which tensile specimens do not fracture within the weld centerline, regardless of temperature. This work demonstrates that a straightforward, PID-based implementation of temperature control at high weld rates can produce high quality welds. Full article

(This article belongs to the Special Issue Advanced Joining Processes and Techniques)

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28 pages, 8532 KiB

Open AccessArticle

Multi-Objective Variable Neighborhood Strategy Adaptive Search for Tuning Optimal Parameters of SSM-ADC12 Aluminum Friction Stir Welding

by Suppachai Chainarong, Rapeepan Pitakaso, Worapot Sirirak, Thanatkij Srichok, Surajet Khonjun, Kanchana Sethanan and Thai Sangthean

J. Manuf. Mater. Process. 2021, 5(4), 123; https://doi.org/10.3390/jmmp5040123 - 16 Nov 2021

Cited by 11 | Viewed by 3314

Abstract

This research presents a novel algorithm for finding the most promising parameters of friction stir welding to maximize the ultimate tensile strength (UTS) and maximum bending strength (MBS) of a butt joint made of the semi-solid material (SSM) ADC12 aluminum. The relevant welding [...] Read more.

This research presents a novel algorithm for finding the most promising parameters of friction stir welding to maximize the ultimate tensile strength (UTS) and maximum bending strength (MBS) of a butt joint made of the semi-solid material (SSM) ADC12 aluminum. The relevant welding parameters are rotational speed, welding speed, tool tilt, tool pin profile, and rotation. We used the multi-objective variable neighborhood strategy adaptive search (MOVaNSAS) to find the optimal parameters. We employed the D-optimal to find the regression model to predict for both objectives subjected to the given range of parameters. Afterward, we used MOVaNSAS to find the Pareto front of the objective functions, and TOPSIS to find the most promising set of parameters. The computational results show that the UTS and MBS of MOVaNSAS generate a 2.13% to 10.27% better solution than those of the genetic algorithm (GA), differential evolution algorithm (DE), and D-optimal solution. The optimal parameters obtained from MOVaNSAS were a rotation speed of 1469.44 rpm, a welding speed of 80.35 mm/min, a tool tilt of 1.01°, a cylindrical tool pin profile, and a clockwise rotational direction. Full article

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16 pages, 9893 KiB

Open AccessArticle

Accuracy and Sheet Thinning Improvement of Deep Titanium Alloy Part with Warm Incremental Sheet-Forming Process

by Badreddine Saidi, Laurence Giraud Moreau, Abel Cherouat and Rachid Nasri

J. Manuf. Mater. Process. 2021, 5(4), 122; https://doi.org/10.3390/jmmp5040122 - 15 Nov 2021

Cited by 2 | Viewed by 2900

Abstract

Incremental forming is a recent forming process that allows a sheet to be locally deformed with a hemispherical tool in order to gradually shape it. Despite good lubrication between the sheet and the tip of the smooth hemisphere tool, ductility often occurs, limiting [...] Read more.

Incremental forming is a recent forming process that allows a sheet to be locally deformed with a hemispherical tool in order to gradually shape it. Despite good lubrication between the sheet and the tip of the smooth hemisphere tool, ductility often occurs, limiting the formability of titanium alloys due to the geometrical inaccuracy of the parts and the inability to form parts with a large depth and wall angle. Several technical solutions are proposed in the literature to increase the working temperature, allowing improvement in the titanium alloys’ formability and reducing the sheet thinning, plastic instability, and failure localization. An experimental procedure and numerical simulation were performed in this study to improve the warm single-point incremental sheet forming of a deep truncated cone in Ti-6Al-4V titanium alloy based on the use of heating cartridges. The effect of the depth part (two experiments with a truncated cone having a depth of 40 and 60 mm) at hot temperature (440 °C) on the thickness distribution and sheet shape accuracy are performed. Results show that the formability is significantly improved with the heating to produce a deep part. Small errors are observed between experimental and theoretical profiles. Moreover, errors between experimental and numerical displacements are less than 6%, which shows that the Finite Element (FE) model gives accurate predictions for titanium alloy deep truncated cones. Full article

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29 pages, 8830 KiB

Open AccessArticle

Modelling and Analysis of Topographic Surface Properties of Grinding Wheels

by Praveen Sridhar, Daniel Mannherz and Kristin M. de Payrebrune

J. Manuf. Mater. Process. 2021, 5(4), 121; https://doi.org/10.3390/jmmp5040121 - 10 Nov 2021

Cited by 2 | Viewed by 3439

Abstract

Grinding is one of the effective manufacturing processes with which to produce highly accurate parts with an ultra-fine surface finish. The tool used to remove materials in grinding is called the grinding wheel. Abrasive grains made of extremely hard materials (alumina, silica, cubic [...] Read more.

Grinding is one of the effective manufacturing processes with which to produce highly accurate parts with an ultra-fine surface finish. The tool used to remove materials in grinding is called the grinding wheel. Abrasive grains made of extremely hard materials (alumina, silica, cubic boron nitride, and diamond) having a definite grit size but a random shape are bonded on the circumferential surface of the grinding wheel. The fabrication process is controlled so that the wheel exhibits a prescribed structure (in the scale of soft to hard). At the same time, the distribution of grains must follow a prescribed grade (in the scale of dense to open). After the fabrication, the wheel is dressed to make sure of its material removal effectiveness, which itself depends on the surface topography. The topography is quantified by the distribution and density of active abrasive grains located on the circumferential surface, the grains’ protrusion heights, and their pore volume ratio. The prediction of the surface topography mentioned above requires a model that considers the entire manufacturing process and the influences on the grinding wheel properties. This study fills this gap in modelling the grinding wheel by presenting a surface topography model and simulation framework for the effect of the grinding wheel fabrication process on the surface topography. The simulation results have been verified by conducting experiments. This study will thus help grinding wheel manufacturers in developing more effective grinding wheels. Full article

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13 pages, 3176 KiB

Open AccessArticle

Thermomechanical Impact of the Single-Lip Deep Hole Drilling on the Surface Integrity on the Example of Steel Components

by Jan Nickel, Nikolas Baak, Pascal Volke, Frank Walther and Dirk Biermann

J. Manuf. Mater. Process. 2021, 5(4), 120; https://doi.org/10.3390/jmmp5040120 - 9 Nov 2021

Cited by 7 | Viewed by 2889

Abstract

The fatigue behavior of components made of quenched and tempered steel alloys is of elementary importance, especially in the automotive industry. To a great extent, the components’ fatigue strength is influenced by the surface integrity properties. For machined components, the generated surface is [...] Read more.

The fatigue behavior of components made of quenched and tempered steel alloys is of elementary importance, especially in the automotive industry. To a great extent, the components’ fatigue strength is influenced by the surface integrity properties. For machined components, the generated surface is often exposed to the highest thermomechanical loads, potentially resulting in transformations of the subsurface microstructure and hardness as well as the residual stress state. While the measurement of the mechanical load using dynamometers is well established, in-process temperature measurements are challenging, especially for drilling processes due to the process kinematics and the difficult to access cutting zone. To access the impact of the thermomechanical load during the single-lip drilling process on the produced surface integrity, an in-process measurement was developed and applied for different cutting parameters. By using a two-color pyrometer for temperature measurements at the tool’s cutting edge in combination with a dynamometer for measuring the occurring force and torque, the influence of different cutting parameter variations on the thermomechanical impact on the bore surface are evaluated. By correlating force and temperature values with the resultant surface integrity, a range of process parameters can be determined in which the highest dynamic strength of the samples is expected. Thermally induced defects, such as the formation of white etching layers (WEL), can be avoided by the exact identification of critical parameter combinations whereas a mechanically induced microstructure refinement and the induction of residual compressive stresses in the subsurface zone is targeted. Further, eddy-current analysis as a non-destructive method for surface integrity evaluation is used for the characterization of the surface integrity properties. Full article

(This article belongs to the Special Issue Surface Integrity in Machining and Post-processing)

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13 pages, 4467 KiB

Open AccessArticle

Effect of Electric Current on SPS Densification of Spherical Copper Powder

by Romaric Collet, Sophie Le Gallet, Frédéric Charlot, Sabine Lay, Jean-Marc Chaix and Frédéric Bernard

J. Manuf. Mater. Process. 2021, 5(4), 119; https://doi.org/10.3390/jmmp5040119 - 5 Nov 2021

Cited by 8 | Viewed by 2652

Abstract

When a current is involved, as in spark plasma sintering, metallic powders are heated by the Joule effect through both tool and specimen. Other mechanisms might occur, but it is difficult to separate the role of the temperature from the role of the [...] Read more.

When a current is involved, as in spark plasma sintering, metallic powders are heated by the Joule effect through both tool and specimen. Other mechanisms might occur, but it is difficult to separate the role of the temperature from the role of the current inside the sample as, in most cases, the two parameters are not controlled independently. In this paper, the consolidation and the densification of a pure copper powder were studied in three configurations for obtaining different electric current paths: (i) current flowing through both the powder and the die, (ii) current forced into the powder and (iii) no current allowed in the powder. Electrical conductivity measurements showed that even low-density samples displayed higher conductivities than graphite by several orders of magnitude. FEM simulations confirmed that these copper specimens were mainly heated by the graphite punches. No modification of the microstructure by the flow of current could be observed. However, the absence of current in the specimen led to a decrease in densification. No significant temperature difference was modeled between the configurations, suggesting that differences are not linked to a thermal cause but rather to a current effect. Full article

(This article belongs to the Special Issue Spark Plasma Sintering: Mechanisms, Materials, and Technology Developments)

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15 pages, 8214 KiB

Open AccessArticle

Mechanical Properties and Failure Mechanisms of Refill Friction Stir Spot Welds

by Guruvignesh Lakshmi Balasubramaniam, Enkhsaikhan Boldsaikhan, Gratias Fernandez Joseph Rosario, Saravana Prabu Ravichandran, Shintaro Fukada, Mitsuo Fujimoto and Kenichi Kamimuki

J. Manuf. Mater. Process. 2021, 5(4), 118; https://doi.org/10.3390/jmmp5040118 - 1 Nov 2021

Cited by 8 | Viewed by 4475

Abstract

Refill friction stir spot welding (RFSSW) is an innovative solid-state welding technology for aluminum structures. The presented study aimed to evaluate the mechanical properties of refill spot welds and their failure mechanisms with the use of industrial test standards. The mechanical properties of [...] Read more.

Refill friction stir spot welding (RFSSW) is an innovative solid-state welding technology for aluminum structures. The presented study aimed to evaluate the mechanical properties of refill spot welds and their failure mechanisms with the use of industrial test standards. The mechanical properties of refill spot welds were compared with those of rivet joints with comparable joint sizes. Static load tests indicated that RFSSW coupons demonstrate higher ultimate shear strengths but slightly lower ultimate tension strengths than those of rivet coupons. Fatigue test results indicated that both RFSSW coupons and rivet coupons demonstrate comparable performances during low-load-level fatigue lap shear tests but RFSSW coupons outperform rivet coupons during high-load-level fatigue lap shear tests. The failure mechanisms of refill spot welds were characterized in terms of external loading, parent metal properties, and weld properties. Refill spot weld failures included parent metal tensile failures, nugget pullouts, and interfacial failures. A refill spot weld may demonstrate one or a combination of these mechanical failures. Although the mechanical tests of refill spot welds demonstrated promising results with predictable failure mechanisms, the metallurgical evolution involved in RFSSW remains a subject to study. Full article

(This article belongs to the Special Issue Frontiers in Friction Stir Welding and Processing)

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19 pages, 4878 KiB

Open AccessArticle

Forces Shapes in 3-Axis End-Milling: Classification and Characteristic Equations

by Niccolò Grossi, Lorenzo Morelli, Giuseppe Venturini and Antonio Scippa

J. Manuf. Mater. Process. 2021, 5(4), 117; https://doi.org/10.3390/jmmp5040117 - 29 Oct 2021

Cited by 4 | Viewed by 2875

Abstract

In 3-axis milling, cutting force analysis represents one of the main methods to increase the quality and productivity of the process. In this context, cutting force shape gives information of both monitoring and prediction of the cutting process. However, the cutting force shape [...] Read more.

In 3-axis milling, cutting force analysis represents one of the main methods to increase the quality and productivity of the process. In this context, cutting force shape gives information of both monitoring and prediction of the cutting process. However, the cutting force shape is not unique, and it changes according to the cutting strategy, tool geometry, and cutting parameters. This paper presents a comprehensive approach to predict and classify cutting force shapes in 3-axis milling operations. In detail, the proposed approach starts by classifying the cutting force shapes for a single fluted endmill (i.e., single flute force shape), and, considering how the single flute force shapes may overlap one another, it extends the classification to a general multiple-fluted endmill. Moreover, the method provides, through analytical equations, angles, and magnitude dimensionless parameters of each key point, describing each shape classified. Finally, the proposed approach was experimentally validated through several milling tests in different cutting conditions. Full article

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16 pages, 8358 KiB

Open AccessArticle

Influence of Pre-Aging on the Hardness and Formability of a Thread Rolled 6056 Aluminum Alloy after Conventional Extrusion and Artificial Aging

by Lisa Winter, Ralph Jörg Hellmig, Kristin Hockauf and Thomas Lampke

J. Manuf. Mater. Process. 2021, 5(4), 116; https://doi.org/10.3390/jmmp5040116 - 29 Oct 2021

Viewed by 2593

Abstract

For the production of aluminum screws, an effective thermomechanical treatment is necessary for enabling high strength combined with good formability. In this study, the influence of pre-aging as initial heat treatment prior to following processing steps was investigated for the precipitation hardenable 6056 [...] Read more.

For the production of aluminum screws, an effective thermomechanical treatment is necessary for enabling high strength combined with good formability. In this study, the influence of pre-aging as initial heat treatment prior to following processing steps was investigated for the precipitation hardenable 6056 aluminum alloy. The short-term low temperature pre-aged condition was compared to a naturally aged one representing storage time in manufacturing. As reference, a solution-annealed condition was used. After these initial heat treatments, conventional extrusion and artificial aging followed prior to final thread rolling. The distribution of strain introduced by these forming processes was numerically investigated using finite element simulation. The initial heat treatment had a significant influence on the mechanical properties achievable after the complete thermomechanical processing route. After extrusion and artificial aging, the highest hardness was achieved by the pre-aged condition. Despite its high initial hardness, this condition exhibited the best formability indicated by well-formed threads combined with the highest hardness achieved after thread rolling. Therefore, pre-aging seems to be an advantageous heat treatment for integration in the manufacturing process of screws due to its beneficial effect on the mechanical properties. Full article

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21 pages, 6504 KiB

Open AccessArticle

Filament Development for Laser Assisted FFF 3D Printing

by Gabriel Borg, Szabolcs Kiss and Arif Rochman

J. Manuf. Mater. Process. 2021, 5(4), 115; https://doi.org/10.3390/jmmp5040115 - 29 Oct 2021

Cited by 4 | Viewed by 5432

Abstract

The aim of this paper was to develop filaments which can be used for laser assisted fused filament fabrication (FFF) 3D printing in order to increase the inter-layer bonding strength of the printed part. The filaments were developed from the most commonly used [...] Read more.

The aim of this paper was to develop filaments which can be used for laser assisted fused filament fabrication (FFF) 3D printing in order to increase the inter-layer bonding strength of the printed part. The filaments were developed from the most commonly used filament materials, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) with the addition of different polymer additives. After performing near infrared (NIR) absorption tests, graphite was selected for further development as it possesses excellent NIR absorption capabilities whilst resulting in consistent filaments’ diameter and being economically viable. A conventional FFF 3D printer was initially used to test the printability of the developed filaments. Afterwards, a fiber couple laser diode was integrated within the printing head to heat up the previously extruded layer. The produced filaments were used to 3D print specimens for shear and tensile testing. With the laser heating, an increase of 14.5% in the elastic modulus and an increase of 27.8% in the tensile strength of the printed parts were noticed. This showed that adding additives into filament materials for localized laser heating is an effective method of increasing the inter-layer bonding, and therefore, the overall strength and durability of FFF 3D printed parts. Full article

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14 pages, 9304 KiB

Open AccessArticle

Effect of Autoclave Pressure and Temperature on Consolidation of Layers and Mechanical Properties of Additively Manufactured (FDM) Products with PLA

by Yousuf Pasha Shaik, Jens Schuster, Aarif Shaik, Mustafa Mohammed and Harshavardhan Reddy Katherapalli

J. Manuf. Mater. Process. 2021, 5(4), 114; https://doi.org/10.3390/jmmp5040114 - 27 Oct 2021

Cited by 10 | Viewed by 4314

Abstract

In additive manufacturing technologies, fused deposition modelling (FDM) is continuing its advancement from rapid prototyping to rapid manufacturing. However, effective usage of FDM is not performed due to the poor mechanical properties of the 3D-printed components. This drawback restricts their usage in many [...] Read more.

In additive manufacturing technologies, fused deposition modelling (FDM) is continuing its advancement from rapid prototyping to rapid manufacturing. However, effective usage of FDM is not performed due to the poor mechanical properties of the 3D-printed components. This drawback restricts their usage in many applications. Much research, such as reinforcing 3D-printed parts with fibers, changing printing parameters (infill density, infill concentration, extrusion temperature, nozzle diameter, layer thickness, raster angle, etc.) are aimed to increase the mechanical properties of 3D-printed parts. This research paper aims to investigate the effect of pressure and temperature on the mechanical properties and consolidation of layers of 3D-printed PLA (Polylactic Acid). Post-treatment was done using a customized autoclave. Autoclave has the capability to maintain 185 °C and 135 bar pressure. Three-dimensional-printed specimens were manufactured using the FDM process with two patterns. Later, the specimens were subjected to various post-treatment processes, then followed with testing and analysis of mechanical properties. Post-treatment process carried out by placing them in an autoclave at certain pressure and temperature conditions. To investigate the repeatability and tolerances, the test series includes a minimum of four to six test specimens. The results indicate that the concentric pattern yields the most desirable tensile, impact, and flexural strength due to the alignment of deposited rasters and better consolidation of layers with the loading direction. The pressure and temperature of the autoclave has a positive effect on the PLA samples, which helped them to reorganize the structure, hence strength properties were enhanced. The test results also compared with injection-molded samples for better understating. Full article

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16 pages, 2560 KiB

Open AccessArticle

Transfer and Optimisation of Injection Moulding Manufacture of Medical Devices Using Scientific Moulding Principles

by Aimee Fitzgerald, Paul McDonald, Declan Devine and Evert Fuenmayor

J. Manuf. Mater. Process. 2021, 5(4), 113; https://doi.org/10.3390/jmmp5040113 - 25 Oct 2021

Cited by 2 | Viewed by 4293

Abstract

Scientific moulding, also known as decoupled injection moulding, is a production methodology used to develop and determine robust moulding processes resilient to fluctuations caused by variation in temperature and viscosity. Scientific moulding relies on the meticulous collection of data from the manufacturing process, [...] Read more.

Scientific moulding, also known as decoupled injection moulding, is a production methodology used to develop and determine robust moulding processes resilient to fluctuations caused by variation in temperature and viscosity. Scientific moulding relies on the meticulous collection of data from the manufacturing process, especially inputs of time (fill, pack/hold), temperature (melt, barrel, tool), and pressure (injection, hold, etc.). This publication presents a use case where scientific moulding was used to enable the transfer and optimisation of an injection moulding process from an Arburg 221M injection moulding machine to an Arburg 375 V model. The part was an endovascular aneurysm repair dilator device where a polypropylene hub was moulded over a high-density polyethylene dilator insert. Upon transfer, multiple studies were carried out, including material rheology study during injection, gate freeze study, cavity balance of the moulding tool, and pressure loss analysis. A design of experiments was developed and carried out on the process with a variety of effects and responses. The developed process cycle time was compared to that achieved theoretically using mathematical modelling and the original process cycle time. The studies resulted in the identification of optimum parameters for injection speed, holding time, holding pressure, cooling time, and mould temperature. The process was verified by completing a 32-shot study and recording part weights and dimensional measurements to confirm repeatability and consistency of the process. The output from the study was a reduction in cycle time by 12.05 s from the original process. A cycle time of 47.28 s was theoretically calculated for the process, which is within 6.6% of the practical experiment results (44.15 s). Full article

(This article belongs to the Topic Modern Technologies and Manufacturing Systems)

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CAD drawing of the dilator hub moulded component. Full article ">Figure 2
Rheology study showing the viscosity of the material (PP)) versus the injection speed used for the manufacture of parts. Notice the viscosity plateau once the injection speed reaches 50 mm/s. Full article ">Figure 3
Sample parts obtained by execution of pressure drop study. The injection volume was varied to allow for the filling of different stages (sprue, runners, gates, and full parts, respectively from top to bottom) on the injection moulding tool cavities. Full article ">Figure 4
Gate seal study results presenting holding time versus part weight. The holding time and pressure were increased until the weight of the parts was stabilised. Full article ">Figure 5
Thermal images taken of moulded parts immediately after the mould was opened using a FLIR thermal imaging camera. Cooling times were varied until the optimum time was achieved. Full article ">Figure 6
Process capability analysis completed on tensile data to determine the Ppk and Cpk values for the process. Full article ">Figure 7
Cycle time analysis illustrating differences in timings for each moulding stage between the original moulding process, the theoretically calculated cycle time, and the newly developed moulding process. Full article ">

13 pages, 2426 KiB

Open AccessArticle

3D Printing of Biomass–Fungi Composite Material: Effects of Mixture Composition on Print Quality

by Abhinav Bhardwaj, Al Mazedur Rahman, Xingjian Wei, Zhijian Pei, David Truong, Matt Lucht and Na Zou

J. Manuf. Mater. Process. 2021, 5(4), 112; https://doi.org/10.3390/jmmp5040112 - 18 Oct 2021

Cited by 29 | Viewed by 6643

Abstract

It is known that 3D printing can facilitate greater design flexibility in the printing of custom shapes for packaging and construction applications using biomass–fungi composite materials. The feasibility of this new method was demonstrated by a preliminary experiment, the results of which were [...] Read more.

It is known that 3D printing can facilitate greater design flexibility in the printing of custom shapes for packaging and construction applications using biomass–fungi composite materials. The feasibility of this new method was demonstrated by a preliminary experiment, the results of which were reported in a journal publication in 2020. As a follow-up, this paper reports on an experimental study on the relationship between the mixture composition (i.e., the psyllium husk powder content) and print quality using this new method. Four mixtures were prepared by varying the amounts of psyllium husk powder (in grams) added to 400 mL of water. The ratios (g/mL) of psyllium husk powder weight (w_p) over volume of water (v_w) for the mixtures were 0, 1:40, 2:40, and 3:40. Each mixture also contained 100 g of biomass–fungi material and 40 g of whole wheat flour. The print quality of the samples was evaluated based on the extrudability and shape stability. The results showed that mixtures without any psyllium husk powder were not extrudable. An increase in the ratio of psyllium husk powder to water from 1:40 to 2:40 resulted in improved print quality; however, when the psyllium husk powder to water ratio was increased to 3:40, the extrudability became worse. This phenomenon was explained by analyzing the rheological properties of the mixtures. Full article

(This article belongs to the Special Issue Anniversary Review and Feature Papers)

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26 pages, 12372 KiB

Open AccessArticle

Towards the Determination of Machining Allowances and Surface Roughness of 3D-Printed Parts Subjected to Abrasive Flow Machining

by Mykhailo Samoilenko, Greg Lanik and Vladimir Brailovski

J. Manuf. Mater. Process. 2021, 5(4), 111; https://doi.org/10.3390/jmmp5040111 - 17 Oct 2021

Cited by 4 | Viewed by 3083

Abstract

Abrasive flow machining (AFM) is considered as one of the best-suited techniques for surface finishing of laser powder bed fused (LPBF) parts. In order to determine the AFM-related allowances to be applied during the design of LPBF parts, a numerical tool allowing to [...] Read more.

Abrasive flow machining (AFM) is considered as one of the best-suited techniques for surface finishing of laser powder bed fused (LPBF) parts. In order to determine the AFM-related allowances to be applied during the design of LPBF parts, a numerical tool allowing to predict the material removal and the surface roughness of these parts as a function of the AFM conditions is developed. This numerical tool is based on the use of a simplified viscoelastic non-Newtonian medium flow model and calibrated using specially designed artifacts containing four planar surfaces with different surface roughnesses to account for the build orientation dependence of the surface finish of LPBF parts. The model calibration allows the determination of the abrasive medium-polished part slip coefficient, the fluid relaxation time and the abrading (Preston) coefficient, as well as of the surface roughness evolution as a function of the material removal. For model validation, LPBF parts printed from the same material as the calibration artifacts, but having a relatively complex tubular geometry, were polished using the same abrasive medium. The average discrepancy between the calculated and experimental material removal and surface roughness values did not exceed 25%, which is deemed acceptable for real-case applications. A practical application of the numerical tool developed was demonstrated using the predicted AFM allowances for the generation of a compensated computer-aided design (CAD) model of the part to be printed. Full article

(This article belongs to the Special Issue Advanced Surface Finishing Processes)

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J. Manuf. Mater. Process., Volume 5, Issue 4 (December 2021) – 39 articles

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