Manufacture Of Complex Research Articles

CONTROL ALGORITHM OF AUTOMATED STAMPING BY ROLLING OF THE CONTROL SYSTEM OF THE ELECTROMECHANICAL DRIVE OF THE VERTICAL DRILLING MACHINE

The control algorithm of automated stamping by rolling of the control system of the electromechanical drive of the vertical drilling machine is relevant in modern conditions due to the rapid development of production automation technologies. Electromechanical drives allow for high precision and productivity in processing materials by pressure, and control systems make the rolling stamping process more efficient and less expensive by optimizing speed and movement angles. SHO, in turn, allows you to create complex geometric shapes of high-quality parts. Research in the field of development of control algorithms is important for improving the processes of manufacturing parts, increasing productivity and reducing production costs. The urgency of the work is to find optimal solutions for automated vertical drilling machines, which will improve the quality of production and the competitiveness of enterprises on the market. This scientific article examines the control algorithm of the automated SHO control system of the electromechanical drive of a vertical drilling machine. An overview of the principles of the machine and the main stages of the SHO process is given. The proposed algorithm is based on the use of a control system that ensures accuracy and stability of the process. An analysis of the efficiency of the algorithm in practice was carried out, the advantages and disadvantages of using this control system were determined. The results of research indicate an increase in the productivity and quality of processing parts due to the implementation of this algorithm. Automated SHO systems can be widely used in mechanical engineering for the manufacture of complex shaped parts. The reliability of these systems is a key factor that determines their efficiency and cost-effectiveness. The development of devices for automatically changing the equipment of the stamping and rolling complex arises with the aim of increasing the efficiency and automation of production processes in industry. Roll stamping is an important technology for the production of metal parts, but the process of changing equipment (such as tools or dies) can be time and resource intensive. The obtained results can be useful for productions using automated rolling stamping systems. They will make it possible to increase the efficiency of the production process, reduce material costs, and also ensure stable and uninterrupted production.

Mimicking human skin constructs using norbornene-pullulan-based hydrogels

There has been a huge demand for engineered skin tissues in the realms of both in vitro and in vivo applications. Selecting the right material scaffold is a critical consideration in making engineered skin tissues, since it should possess a good balance between elasticity and mechanical stability while promoting an adequate cell microenvironment to support both the dermal and the epidermal compartments of skin tissue. In this study, 3D-bioprinted norbornene-pullulan photocrosslinkable hydrogels were utilized as alternative scaffolds to produce epithelized dermal skin models. By employing visible light, 2.5 mm3 cell-laden hydrogels could be printed in 10 s. The thiol-ene photocrosslinking chemistry employed in this work enabled the formation of a well-defined extracellular matrix with orthogonal crosslinks, where encapsulated fibroblasts maintained high cellular viability rates. Through this method, an epidermal layer could be grown on top of the fibroblasts. The coexistence and interaction of human fibroblasts and keratinocytes were visualized by determining the expression of specific markers. This approach represents a promising starting point for the development of photocrosslinkable hydrogel-based human skin constructs by using thiol-ene norbornene chemistry, paving the way toward manufacture of complex in vitro models of human tissues.  

Process Planning for Large Container Ship Propeller Shaft Machining Based on an Improved Ant Colony Algorithm

To accommodate the production and manufacture of complex and customized marine components and to avoid the empirical nature of process planning, machining operations can be automatically sequenced and optimized using ant colony algorithms. However, traditional ant colony algorithms exhibit issues in the context of machining process planning. In this study, an improved ant colony algorithm is proposed to address these challenges. The introduction of a tiered distribution of initial pheromones mitigates the blindness of initial searches. By incorporating the number of iterations into the expectation heuristic function and introducing a ‘reward–penalty system’ for pheromones, the contradictions between convergence speed and the tendency to fall into local optima are avoided. Applying the improved ant colony algorithm to the process planning of large container ship propeller shaft machining, this study constructs a ‘distance’ model for each machining unit and develops a process constraint table. The results show significant improvements in initial search capabilities and convergence speed with the improved ant colony algorithm while also resolving the contradiction between convergence speed and optimal solutions. This verifies the feasibility and effectiveness of the improved ant colony algorithm in intelligent process planning for ships.

Viable route to the manufacture of short carbon fiber-rich UHTC complex shapes with enhanced toughness

ZrB2 - based pasted, containing 5, 20, 45, 60 vol% short carbon fibers (Cf), were prepared in order to obtain complex shapes via direct ink writing, which were then sintered by hot pressing. The rheological behavior of the pastes indicated that at low Cf concentrations, the fibers act as a lubricant decreasing the paste viscosity. Above 20 vol% Cf, they act also as a binder creating an interconnected network that dominates over the lubrication effect, resulting in a viscosity increase. Complex shapes in the form of a hollow cylinder and a winglet with a functionally graded composition were then extruded and hot pressed, using a versatile powder bed method that enabled full densification with no need to use ad-hoc machined graphite inserts. Bars obtained from the direct ink writing process resulted in high alignment of the short fiber and displayed fracture toughness increase of 54% over that of the unreinforced matrix, while demonstrating a 42% increase with respect to conventionally hot pressed dry mixtures of ZrB2 and short fibers.This work shows the great potential of manufacturing complex shapes in ultra-high temperature ceramics matrices reinforced with short fibers for a plethora of design possibilities, including functional grading with control over layer composition, thickness and even alignment of short fiber.

Low-cost, versatile, and highly reproducible microfabrication pipeline to generate 3D-printed customised cell culture devices with complex designs.

Cell culture devices, such as microwells and microfluidic chips, are designed to increase the complexity of cell-based models while retaining control over culture conditions and have become indispensable platforms for biological systems modelling. From microtopography, microwells, plating devices, and microfluidic systems to larger constructs such as live imaging chamber slides, a wide variety of culture devices with different geometries have become indispensable in biology laboratories. However, while their application in biological projects is increasing exponentially, due to a combination of the techniques, equipment and tools required for their manufacture, and the expertise necessary, biological and biomedical labs tend more often to rely on already made devices. Indeed, commercially developed devices are available for a variety of applications but are often costly and, importantly, lack the potential for customisation by each individual lab. The last point is quite crucial, as often experiments in wet labs are adapted to whichever design is already available rather than designing and fabricating custom systems that perfectly fit the biological question. This combination of factors still restricts widespread application of microfabricated custom devices in most biological wet labs. Capitalising on recent advances in bioengineering and microfabrication aimed at solving these issues, and taking advantage of low-cost, high-resolution desktop resin 3D printers combined with PDMS soft lithography, we have developed an optimised a low-cost and highly reproducible microfabrication pipeline. This is thought specifically for biomedical and biological wet labs with not prior experience in the field, which will enable them to generate a wide variety of customisable devices for cell culture and tissue engineering in an easy, fast reproducible way for a fraction of the cost of conventional microfabrication or commercial alternatives. This protocol is designed specifically to be a resource for biological labs with limited expertise in those techniques and enables the manufacture of complex devices across the μm to cm scale. We provide a ready-to-go pipeline for the efficient treatment of resin-based 3D-printed constructs for PDMS curing, using a combination of polymerisation steps, washes, and surface treatments. Together with the extensive characterisation of the fabrication pipeline, we show the utilisation of this system to a variety of applications and use cases relevant to biological experiments, ranging from micro topographies for cell alignments to complex multipart hydrogel culturing systems. This methodology can be easily adopted by any wet lab, irrespective of prior expertise or resource availability and will enable the wide adoption of tailored microfabricated devices across many fields of biology.

Parametrical analysis of a novel solar cascade photovoltaic system via full-spectrum splitting and residual-spectrum reshaping

In this study, a novel cascade photovoltaic power generation system via full-spectrum splitting and residual-spectrum reshaping is proposed to realize the cascade conversion of solar energy. A cavity-structured absorber and outer-wall emitter combined device is designed for reshaping the residual infrared spectrum, and the corresponding physical model is also established. The parametric analysis of the whole system is conducted to investigate the effect of cavity structure, second-stage cell, spectrum-split frequency, selective emitter and concentration ratio on the system performance. The results indicate that the system efficiency can reach 34.32%, which is higher than that of solar photovoltaic (27.6%) by 6.72 percentage points. It is founded that the solar thermophotovoltaic conversion system equipped with the cavity-structured absorber, whose absorption efficiency can reach more than 99.06%, can efficiently absorb and utilize the infrared residual spectrum. The cavity structure can avoid the manufacture of complex micro/nano structured materials and the high design cost of selective absorber. When Si is selected as second-stage photovoltaic cell and the selective emitter is used, the system efficiency is higher than that using GaSb cell by about 2–3 percent points. Besides, the lower cost of Si cell also provides certain application advantages. The result of this study paves a theoretical guiding for the development and application of solar photovoltaic technology.

Preliminary laser treatment of materials for diffusion bonding in space and aviation technologies

The paper investigates the possibility of improving the technology of diffusion welding, which can be used both for joining dissimilar materials for the manufacture of complex devices in the aerospace industry on the ground, and for repair and design in outer space. A laser treatment by nanosecond laser pulses of the ultraviolet range was carried out for surface modification of industry alloys (CrNi55CuВZn, steel AISI 316, Cu–Cr bronze) used in space technology due to high values of thermal and electrical conductivity. It was shown that the preliminary laser treatment leads to an improvement in the properties of the weld: an increase in tensile strength by more than 10%, and tensile strain by more than 20% for certain joints of materials. Also, laser pre-processing can improve the productivity of the welding process, in particular, reduce the temperature and shorten the welding time.

Off-the-Shelf, iPSC-Derived CAR-NK Cells Multiplexed-Engineered for the Avoidance of Allogeneic Host Immune Cell Rejection

Allogeneic off-the-shelf cell therapies offer distinct advantages over conventional autologous cell therapies in terms of scaled manufacturing, on-demand availability and optimization of cellular starting material. A unique consideration in the use of allogeneic cell therapies is the potential for immune cell-mediated recognition of the allogeneic cell product by the patient's immune system. CAR T-cell therapies are commonly combined with conditioning chemotherapies that suppress a patient's immune system, creating a suitable window of activity to elicit clinical response. However, protracted lympho-conditioning also affects immune reconstitution and can negatively impact the rate of infection. Alternative approaches to prevent allorejection may therefore help to enhance the efficacy of the therapy while preserving the immune system of the patient.Elimination of cell-surface human leukocyte antigen (HLA) molecule expression by genetic knockout (KO) has long been known to abrogate T-cell reactivity. However, loss of class I HLA elicits NK cell-mediated recognition and clearance, and therefore must be combined with other immune-modulating strategies to limit host NK cell reactivity. Allogeneic models combining class I HLA deletion with NK cell inhibitory molecules, such as HLA-E and CD47, have been shown to abrogate NK cell reactivity in mouse models. However, HLA-E is the canonical activator of NKG2C, a dominant activating receptor found on human NK cells. Likewise, the expression of signal regulatory protein alpha (SIRPα), the major interactor for CD47, is mostly restricted to macrophages and dendritic cells and not human NK cells, and the observed effects of this immune-modulating strategy in the mouse system may only offer partial or incomplete immune evasion in the human system.In this study, we provide details of a bona fide off-the-shelf strategy where iPSC-derived NK (iNK) cell therapy is multiplexed engineered with a novel combination of immune-evasion modalities; beta 2 microgobulin (B2M) KO to prevent CD8 T-cell mediated rejection; class II transactivator (CIITA) KO to prevent CD4 T-cell mediated rejection; and CD38 KO to enable combination with anti-CD38 mAbs, which can be administered to deplete host alloreactive lymphocytes, including both NK and T cells. In vitro mixed lymphocyte reaction (MLR) data demonstrated that upon co-culture with allogeneic PBMCs, B2M KO iNK cells stimulated less T-cell activation than their B2M sufficient counterparts as evidenced by reduced CD38, 41BB, and CD25 levels on T cells. Additionally, B2M KO iNK cells impaired T-cell expansion over the duration of co-culture, resulting in a 50% decrease in expansion at the peak of the control response. However, B2M KO iNK cells were depleted over time, suggesting activation of an NK cell “missing self” response by the peripheral blood NK (pbNK) cells.In contrast, when the assay was performed in the presence of anti-CD38 mAb, depletion of B2M KO iNK cells was blocked, and instead B2M KO iNK cell numbers increased by 3.5-fold, comparable to the iNK cell numbers found in the control arm (cultured without allogeneic PBMCs). Interestingly, pbNK cell numbers decreased, while T-cell activation and expansion remained lower than in B2M-sufficient MLR cultures. Furthermore, when B2M KO iNK cells were cocultured with tumor cells and anti-CD38 mAb in vitro, ADCC was comparable to the B2M sufficient cells, indicating uncompromised effector function. Finally, in vivo studies suggested that co-administration of anti-CD38 mAbs can significantly enhance the persistence of B2M KO iNK cells in the presence of allogeneic pbNK cells as seen in the spleen and bone marrow (Figure 1).Together these data demonstrate that the combination of triple-gene knockout of CD38, B2M and CIITA with a CD38-targeting mAb is an effective strategy to avoid host immune rejection, and highlights the potential advantages of multiplexed engineered iPSCs to facilitate large-scale manufacture of complex engineered, off-the-shelf cellular therapies. [Display omitted] DisclosuresWilliams: Fate Therapeutics: Current Employment. Malmberg: Merck: Research Funding; Vycellix: Consultancy; Fate Therapeutics: Consultancy, Research Funding. Lee: Fate Therapeutics, Inc.: Current Employment. Bjordahl: Fate Therapeutics: Current Employment. Valamehr: Fate Therapeutics, Inc.: Current Employment.

Qualitative and Quantitative Microstructural Analysis of Copper for Sintering Process Optimization in Additive Manufacturing Applications

Abstract This work will present possibilities for the characterization of copper powder green bodies and sintered copper microstructures during pressureless sintering. The introduction of new parameters to microstructural characterization based on qualitative and quantitative microstructural analysis will facilitate the systematic optimization of the sintering process. As a result of the specific evaluation of the microstructure evolution, conventional isothermal sintering could be successfully replaced by multi-step temperature profiles, thus achieving sintering densities of more than 99 % by simultaneously reducing process time. This systematic optimization of the sintering process of Cu through specific microstructural analysis may now be applied to sinter-based manufacturing technologies such as Binder Jetting and Metal Powder Injection Moulding, enabling the manufacture of complex and highly conductive Cu parts for applications in electronics.

The use of reliability indicators in the design of die tooling of technological processes of hot die forging

The article discusses the use of a number of indicators of the reliability of the functioning of the hot forming process to substantiate the choice of the number of die inserts (die streams) and selection of grades of tool steels for their manufacture. There are such used reliability indicators as the probability of the absence of typical defects in the shape of the stamped forgings, the probability of predominant types of exploitative refusals of the stamp, and the absence of failures in the implementation of the technological process as a whole. The rationale for the expediency of choosing a pre-stream of the die for stamping an axisymmetric forging with a high degree of complexity taking into account the possibility of occurrence of such shape defects as clamping, shooting, and incomplete forging radii during stamping, is considered. When the choice of the grade of tool steel for die inserts was taken into account, there was the occurrence of such typical types of their exploitative refusals as adhesion wear of die streams, the formation of hot cracks and plastic crushing of the forming elements of the stamp streams. The appropriate organizational and technical decisions are adopted on the basis of a comparison of cost indicators characterizing the production costs due to scrap forgings. They are caused by the formation of shape defects during stamping and the occurrence of exploitative refusals of dies. In addition, there are the costs for the manufacture of more complex die tooling and its exploitation, i.e. production quality costs.

Technology fusion of metal injection moulding and selective laser melting for the manufacture of complex and multifunctional (hydraulic) components

Selective laser melting (SLM) and metallic injection moulding (MIM) are established processes for the production of high-performance metallic components for small and large series. In the aerospace industry, where very high demands are placed on materials and components, both processes are still considered to be relatively new. In both processes, the conventional titanium alloy Ti-6Al-4V can be used in the form of powder. Currently, both technologies are only considered separately. By fusing components of the same type, multifunctional components with a high lightweight construction potential can be produced.
 In order to generate direct material fusion, the MIM component must be mechanically processed accordingly. In addition, suitable SLM process parameters must be developed in order to ensure both generative construction and high joint strength. To this end, a characterisation of the joining zone and the static joint strength was carried out. Furthermore, pressure test samples were designed and examined both statically and for fatigue strength. Thus, a high static joint strength could be proven. The compression test samples also withstood a fatigue strength of over 1 million cycles.

A spark-plasma-sintering approach to the manufacture of anisotropic Nd-Fe-B permanent magnets

Sintered Nd-Fe-B permanent magnets are the first choice for electro-mechanical devices that rely on hard-magnetic materials to provide strong magnetic fields in a variety of operating conditions. However, the limitations of conventional powder-metallurgy methods regarding the complexity of the magnet’s geometry restrict the design freedom for electrical motors. Here, we propose a spark-plasma-sintering (SPS) approach to the waste-free net-shape manufacture of anisotropic Nd-Fe-B magnets. We investigated the effect of the SPS parameters on the density, magnetic properties and microstructure of disc-shaped samples prepared from a rare-earth-lean jet-milled powder. The absence of a grain-boundary phase and the presence of α-Fe in the as-sintered samples were identified as the main factors hindering the development of the intrinsic coercivity. The observed microstructural features were correlated with electrical effects specific to the rapid, non-equilibrium SPS. A post-SPS thermal treatment was found to be necessary for achieving the hard-magnetic properties. Our findings pave the way towards developing an SPS-based sintering procedure with great potential for the manufacture of complex- and net-shape permanent magnets for high-performance electrical devices.

3D printing and characterization of a soft and biostable elastomer with high flexibility and strength for biomedical applications

Recent advancements in 3D printing have revolutionized biomedical engineering by enabling the manufacture of complex and functional devices in a low-cost, customizable, and small-batch fabrication manner. Soft elastomers are particularly important for biomedical applications because they can provide similar mechanical properties as tissues with improved biocompatibility. However, there are very few biocompatible elastomers with 3D printability, and little is known about the material properties of biocompatible 3D printable elastomers. Here, we report a new framework to 3D print a soft, biocompatible, and biostable polycarbonate-based urethane silicone (PCU-Sil) with minimal defects. We systematically characterize the rheological and thermal properties of the material to guide the 3D printing process and have determined a range of processing conditions. Optimal printing parameters such as printing speed, temperature, and layer height are determined via parametric studies aimed at minimizing porosity while maximizing the geometric accuracy of the 3D-printed samples as evaluated via micro-CT. We also characterize the mechanical properties of the 3D-printed structures under quasistatic and cyclic loading, degradation behavior and biocompatibility. The 3D-printed materials show a Young's modulus of 6.9 ± 0.85 MPa and a failure strain of 457 ± 37.7% while exhibiting good cell viability. Finally, compliant and free-standing structures including a patient-specific heart model and a bifurcating arterial structure are printed to demonstrate the versatility of the 3D-printed material. We anticipate that the 3D printing framework presented in this work will open up new possibilities not only for PCU-Sil, but also for other soft, biocompatible and thermoplastic polymers in various biomedical applications requiring high flexibility and strength combined with biocompatibility, such as vascular implants, heart valves, and catheters.

Effects of laser shock processing on abrasion resistance of high speed steel cutting tools

Purpose As a key basic component used in machining, high-speed steel (HSS) tools often prone to wear and failure during machining. Therefore, the purpose of this study is to adopt a suitable approach to improve the stability of the cutting force, the service life and the wear resistance. Design/methodology/approach Laser shock processing (LSP) was used to process the tool rake face and the tribological test was performed with ball-on-disk wear tester. Findings Experimental results show that cutting force of the LSP-treated tool is lower than untreated tool under the same cutting conditions. Wear rate of the tool nose treated by LSP decreases obviously and the tool life increases by 40 per cent. Originality/value HSS is often used in the manufacture of complex cutting tools. The main value of this article is to improve the tool surface wear resistance, thereby extending the service life of cutter. This paper is valuable not only in theory but also with reference value in engineering practice.

Geometrical effects on residual stress in selective laser melting

Selective laser melting is an increasingly attractive technology for the manufacture of complex and low volume/high value metal parts. However, the inevitable residual stresses that are generated can lead to defects or build failure. Due to the complexity of this process, efficient and accurate prediction of residual stress in large components remains challenging. For the development of predictive models of residual stress, knowledge on their generation is needed. This study investigates the geometrical effect of scan strategy on residual stress development. It was found that the arrangement of scan vectors due to geometry, heavily influenced the thermal history within a part, which in turn significantly affected the transverse residual stresses generated. However, irrespective of the choice of scanned geometry and the thermal history, the higher magnitude longitudinal stresses had consistent behaviour based on the scan vector length. It was shown that the laser scan strategy becomes less important for scan vector length beyond 3 mm. Together, these findings, provide a route towards optimising scan strategies at the meso-scale, and additionally, developing a model abstraction for predicting residual stress based on scan vectors alone.

Thermal Mechanical Processing of Press and Sinter Al-Cu-Mg-Sn-(AlN) Metal Matrix Composite Materials

The forging of sintered aluminum powder metallurgy alloys is currently viewed as a promising industrial technology for the manufacture of complex engineered products. The powder metallurgy process facilitates the use of admixed ceramic particles to produce aluminum metal matrix composites. However, fundamental data on the thermal-mechanical response of commercially relevant powder metallurgy alloy systems under varying conditions of temperature and strain rate are lacking. To address this constraint, the current study investigates the thermal-mechanical processing response of a family of metal matrix composite materials that employ a commercially exploited base alloy system coupled with admixed additions of aluminum nitride. Industrially-sintered compacts were tested under hot compression using a Gleeble 3500 thermal-mechanical test system to quantify their flow behavior. The nominal workability was assessed as a function of material formulation, sintered preform condition, and processing parameters (temperature and strain rate). Optical metallography and electron backscatter diffraction were used to observe the grain evolution through deformation. Full densification was achieved for materials with ceramic concentrations of 2% volume or less. Zener-Hollomon constituent analyses were also completed to elucidate a more comprehensive understanding the flow behavior inherent to each material. Flow behavior varied directly with the sintered density, which was influenced by the concentration and nature of ceramic particulate.

Direct slicing of T-spline surfaces for additive manufacturing

PurposeT-spline is the latest powerful modeling tool in the field of computer-aided design. It has all the merits of non-uniform rational B-spline (NURBS) whilst resolving some flaws in it. This work applies T-spline surfaces to additive manufacturing (AM). Most current AM products are based on Stereolithograph models. It is a kind of discrete polyhedron model with huge amounts of data and some inherent defects. T-spline offers a better choice for the design and manufacture of complex models.Design/methodology/approachIn this paper, a direct slicing algorithm of T-spline surfaces for AM is proposed. Initially, a T-spline surface is designed in commercial software and saved as a T-spline mesh file. Then, a numerical method is used to directly calculate all the slicing points on the surface. To achieve higher manufacturing efficiency, an adaptive slicing algorithm is applied according to the geometrical properties of the T-spline surface.FindingsExperimental results indicate that this algorithm is effective and reliable. The quality of AM can be enhanced at both the designing and slicing stages.Originality/valueThe T-spline and direct slicing algorithm discussed here will be a powerful supplement to current technologies in AM.

Evaluation of fatigue crack propagation behaviour in Ti-6Al-4V manufactured by selective laser melting

Total fatigue life performance of high strength titanium alloy Ti-6Al-4V manufactured by Additive Manufacturing (AM) based methods such as Selective Laser Melting (SLM) is of significant interest and has gained much attention recently. Researchers often compare the total fatigue life of materials manufactured from SLM with conventional manufacture, and often the SLM lives are reduced because cracks initiate from “defects” such as porosity or Lack of Fusion (LOF). But for repair and alternative manufacture of complex and critical aerospace structures for example, the crack growth/propagation phase of the fatigue process is also very important and it has not been studied as extensively. The aim of the work presented here was to evaluate and better understand crack propagation under constant amplitude loading in Ti-6Al-4V samples manufactured using SLM with a variety of layer thicknesses and build directions (vertical or horizontal). The “as-manufactured” condition was studied, with no post heat treatment. Cracks typically initiated at LOF features which had a negative impact on the total fatigue life. The focus here was on the crack growth phase. Modelling was performed with a conventional Linear Elastic Fracture Mechanics approach using literature data obtained from testing on Compact Tension (C(T)) specimens which were also in the as-manufactured condition with a variety of build directions. The modelling provided a very useful correlation of the data and provided a way of assessing the LOF features in terms of an equivalent initial crack. The crack growth properties of the SLM cases were also compared against literature data for conventionally manufactured material. The work will lead to a better understanding of fatigue crack growth characteristics for components manufactured by AM methods such as SLM. That understanding is an essential requirement for full certification and acceptance into service for critical applications such as aerospace structures.

Laser Direct Metal Deposition (LDMD) – an Overview

Laser Direct Metal deposition (LDMD) is an additive manufacturing process, it is used to manufacture complex 3D objects directly from CAD files. Laser creates melt region on surface of substrate and powder material blown on to the laser-induced melt pool to form a layer. After a layer deposition, nozzle and laser assembly raised vertically upward by calculated small increment. Next layer is built on previous one, thus a 3D part is built layer by layer. Different FEA Tools were used like COMSOL, ANSYS, ABAQUS etc, and finite element models are developed to numerically simulate heat transfer and coupled thermal phenomena to analyze the influence of various parameters on thermal history. Thermal cycles experienced at different locations and thermal gradient at mutually perpendicular directions are studied. Influence of thermal loading on the model’s distortion is analyzed. LDMD process finds potential application in rapid tooling, prototyping, precision repair work, and manufacture of complex, intricate components with varying compositions, work on challenging materials like Titanium alloys, superalloys etc. Applications are repair of moulds, dyes, motor, gear component etc, work on challenging material(Titanium alloys, superalloys), fabrication of dissimilar metals and so on.

Selective Laser Melting of Magnesium and Magnesium Alloy Powders: A Review

Magnesium-based materials are used primarily in developing lightweight structures owing to their lower density. Further, being biocompatible they offer potential for use as bioresorbable materials for degradable bone replacement implants. The design and manufacture of complex shaped components made of magnesium with good quality are in high demand in the automotive, aerospace, and biomedical areas. Selective laser melting (SLM) is becoming a powerful additive manufacturing technology, enabling the manufacture of customized, complex metallic designs. This article reviews the recent progress in the SLM of magnesium based materials. Effects of SLM process parameters and powder properties on the processing and densification of the magnesium alloys are discussed in detail. The microstructure and metallurgical defects encountered in the SLM processed parts are described. Applications of SLM for potential biomedical applications in magnesium alloys are also addressed. Finally, the paper summarizes the findings from this review together with some proposed future challenges for advancing the knowledge in the SLM processing of magnesium alloy powders.