3D Printing and Additive Manufacturing Technologies

In this work, volume contraction of powder layer and convective flow in the melt pool during laser spot melting of Ti–6Al–4V powder layer are investigated using a transient two-dimensional finite element model. An algorithm, coupled with the finite element model, accounting for volume contraction due to melting of porous powder to a denser liquid is proposed, which is thereafter used to understand the role of natural and Marangoni convection on the melt pool behaviour. Results for the melt pool characteristics, such as melt pool geometry, melt pool fluid flow dynamics and thermal behaviour are presented.

The repair of steel plate using welding can be optimized by multi-layer deposition. In this numerical study, semi-automatic arc welding is used to deposit single-track multi-layers of mild steel on a same material mild steel plate. Three-dimensional transient numerical simulations of the transport phenomena involved in the melt pool are performed. The model considers heat transfer, convective and radiative losses, phase change, re-melting, solidification, and buoyancy and Marangoni convection driven fluid flow in the melt pool. The model predicts the temperature and velocity fields, and the evolution of melt pool shape and size.

Laser metal deposition (LMD) is a metal additive manufacturing technique where in a metal component is built through layer-by-layer approach. Laser metal deposition is broadly used in fabrication and repairing of complex components for aerospace applications. The objective of this research paper is to focus on the bonding strength of Ti–6Al–4V alloy deposit fabricated under optimal process parameters and the substrate. Three-point bending test has been carried out on Ti–6Al–4V deposit and substrate shown that the bending strength of Ti–6Al–4V deposit is closer to the Ti–6Al–4V substrate. This result helps in restoration of complex aero engine parts with reduced lead-time and cost.

The Rayleigh–Bénard is also known as Gibbs–Marangoni effect. In this effect the mass transfer occurs along an interface between liquid and air due to its surface tension gradient. Rayleigh–Bénard convection effect plays a vital role in getting smooth continuos track in laser melting process. The Rayleigh–Bénard convection enhances the heat transfer phenomena throughout the powder bed. The type of Rayleigh–Bénard convection flow identified during simulation is source flow. Rayleigh–Bénard convection flow which shows the pattern of clockwise flow is defined as source flow. Overall convection flow found in this studies are of clockwise flow. This study mainly focuses its attention on the effect of Rayleigh–Bénard convection flow in laser melting process.

Rapid prototyping is a manufacturing process in which a computer-aided design (CAD) model is used to fabricate a physical model without the use of fixtures, tools, and human intervention. The prototype is made by deposition of material in layers. The major advantage of this manufacturing process is that it can fabricate complex part quickly with minimum loss of material. There are many rapid prototyping techniques available commercially. Fused deposition modelling (FDM) is one of the most widely acceptable methods in industry due to its simplicity of operation and ability to fabricate parts with locally controlled properties. However, the surface of the FDM parts shows a very low surface finish. In order to find out the effect of important factors that influence the surface roughness, two machining parameters such as layer thickness and orientation are considered in this paper. The specimens are fabricated with various combination of orientation and layer thickness in a FDM machine which uses Acrylonitrile Butadiene Styrene (ABS) plastics. Roughness of the top and side surface is measured with a stylus profilometer. The parameters are classified into ‘cost component’ which comprises number of layers, part building time, part and support materials and a ‘quality component’ which comprises roughness of top and side surface. The best orientation-layer thickness combination is found out statistically considering trade-off between considering the cost and quality components. In order to enhance surface finish, the above-selected specimen is subjected to chemical post treatment which shows a significant level of surface finish.

This paper presents a novel post-processing tool, namely selective melting (SM) tool for thermally assisted finishing (TAF) of Fused Deposition Modelling (FDM) build parts. During FDM process layer upon layer, part fabrication leads to an inherent surface constraint, i.e. generation of stepped surfaces that cannot be avoided while fabrication of parts. Hence, these stepped surfaces need to be removed to achieve desired surface quality of FDM build parts for different applications. Therefore, post-finishing has been performed by means of selective melting of stepped surfaces. This paper studied coupled parameters during pre- and post-processing operation and their effect and estimation of randomness in peak to valley height variation on surface profile. Post-finishing of the FDM modelled surfaces is performed by a significant amount of feed rate variation along the tool path which results in temperature variation over the part surface. Feed rate regulation is used in this research to vary the depth of melting as the part surface changes its orientation along the tool path. Proposed selective melting (SM) tool adaptively melts the requisite or extra material to provide adaptive finishing tool path planning for improving the surface finish conditions. The effectiveness of the proposed technique was analysed and studied. The results showed that the proposed approach played a significant role in improving the surface finish conditions of FDM build parts.

Additive Manufacturing (AM) systems have gained popularity, due to their capability of producing parts in layer-by-layer manner with any degree of complexity. Although in the last three decades, various commercial AM systems have been developed, however, high cost of the indigenous materials used in commercial machines is the major hindrance for wide applications. Therefore, an economically viable system needs to be developed by exploring the existing manufacturing systems, i.e., CNC milling, etc., as AM technique. To perform AM operation on CNC milling machine, a toolpath is to be required which could be traced by the deposition tool to fabricate the part by adding material in layer-by-layer fashion. In this regard, the present paper proposes a raster and perimeter based toolpath for performing additive manufacturing on existing CNC milling machine. MATLAB platform has been used for algorithm implementation and development of toolpath. Graphical User Interface (GUI) has also been developed in MATLAB to provide the easy access of all parameters related to the toolpath generation, i.e., road gap, slice height, number of contours, etc. To check the feasibility of developed toolpath, experiments have been conducted on existing milling machine by developing and mounting a customized material deposition tool. 3D parts have been fabricated successfully using the developed toolpath. Results show that developed toolpath can be used for performing AM on CNC milling machine.

One of the most promising additive manufacturing techniques is selective laser melting process. It is a complex process, which involves physical phenomena, such as absorption of the laser beam in the powder bed, melting and re-solidification, diffusive and radiative heat transport in the powder, diffusive and convective heat transport in the melt pool, gravity effects, etc. In this study, a two-dimensional lattice Boltzmann model is formulated to investigate melting of a uniformly packed powder bed under the irradiation of laser beam during the selective laser melting process. In the model, phase change of individual powder particle is considered mesoscopically. The results give an insight into the details of heat transfer and melting in the powder bed and formation of the mushy zone. These mesoscopic results can be useful to set parameters of the powder bed in additive manufacturing processes. The model developed can be applied to any powder bed based additive manufacturing process.

In rapid prototyping (RP), 3D printing is growing fast due to its ability to build different complex geometrical shapes and structures in least possible time. The mechanical behavior of 3D printed parts depends on the interaction of different process parameters and the raw material properties. In this work, the effect of process parameters, namely, nozzle diameter, layer thickness, and part bed temperature, has been studied on mechanical properties like tensile strength and flexural strength in 3D printing process. Material used in the study is solidified polylactic acid (PLA). It was observed that tensile strength and flexural strength increased with increase in part bed temperature. It was further observed that tensile strength decreased with increase with layer thickness whereas flexural strength increased. With respect to nozzle diameter, it was observed that tensile strength increased while flexural strength initially decreased and then increased with increase in nozzle diameter. SEM analysis has been done to evaluate the mechanism of failure of the parts.

Additive manufacturing (AM), a layer-wise manufacturing technique using CAD model and raw material as input poses new challenges to conventional manufacturing. Without any efforts required for material removal and tooling, the product build time and material consumption can be controlled and estimated effectively with high accuracy and quality. Further, AM has the necessary capability of manufacturing products as per their final dimensional and functional needs in one operation thereby cutting down the subsequent finishing and assembling steps. AM thus reduces total time for product manufacturing simultaneously eliminating capital and operational costs for further steps, inventory and material handling. However, process and material challenges are the techno-economic barriers for adapting AM in industries for commercialization. The paper has specifically chosen metal powders for analysis as their properties and process capabilities are better than non-metals. The data collected on the present status of the AM technologies globally (related to the sale of 3D printers both in numbers and revenues) based on the various reports are analysed to forecast market of 3D printers for the next 10 years. Final conclusions are made by predicting the values using regression technique. The paper analyses the global patent trends during last 15 years in various countries so as to assess the futuristic AM technologies.

The paper focuses on applying additive manufacturing in a healthcare sector. In healthcare wound healing remains a challenging clinical problem, for chronic wounds rather than in acute wound. It shows that chronic wound would take much time to heal. In general wound dressing product available in market for chronic wounds have irregular pores. The model of the wound dressing is categorized depending upon the type of wound; size of the wound. The product will be customized for person to person. Through additive manufacturing technology customization of the product can be provided. The aim of this paper is to design and develop a wound dressing model with pores for chronic wound using additive manufacturing technology. The outcome of the paper would result in customized product for chronic wound.

This paper deals in identifying a complex geometry problem related to health care sector. Paper focuses on identifying a problem in health care which is identified in the area of deformities. Non-surgical treatment for congenital talipes equino varus (clubfoot) deformity known as Ponseti method involves many complications thereby leading to the recurrence of the deformity. In this regard, design and development of customized orthosis that can be used as an alternate solution for Ponseti method for treating clubfoot deformity through AM technology is carried out in this work.

Selective laser sintering (SLS) empowers the fast, flexible, cost-efficient, and easy manufacture of prototypes for various application of required shape and size by using powder based material. The physical prototype is important for design confirmation and operational examination by creating the prototype unswervingly from CAD data. In SLS procedure optimization of construction parameters of good responses, will also help to save time and material. In this work, optimal SLS process parameters, by varying the laser power, bed temperature and layer thickness on surface quality of Length, Depth and Surface roughness for the designed part by using Polyamide and also evaluate the part quality by using Coordinate measuring machine (CMM). The experimentations were carried out rendering to the Taguchi parametric strategy L9 at various combinations of process parameters and arithmetical optimization method ANOVA was used to decide the optimal levels and to find the percentage of contribution of the process parameters. The results show that the Laser power is the most important factor followed by the Bed Temperature and Layer thickness for maximizing the Length and Depth, Minimizing Surface roughness of the SLS processed Polyamide. This optimized process capability paves the way for the society.

This paper presents an integrated design cycle of reverse engineering (RE) and rapid prototyping (RP) for reconstruction of a damaged parts in industry and production systems by taking gear wheel in a rotating machinery as an example. In order to replace the damaged part or destructive part, it is required to change urgently with new part to avoid the financial and production loss to the industry. This can be possible with the help of 3D scanning and additive manufacturing. 3D scanning help to capture digital information of parts from space to CAD software. The physical to electronic translation is done by a layered digitizing method called Deconstruction and semi-automated software tools are used to create a CAD virtual solid model. Conventional CAD tools are used to manipulate the model of damaged part and reconstruct damaged area to form new one by CAD tools as necessary. A newly created 3D solid model is translated from virtual to physical model by using additive manufacturing process. Here FDM process is used. A designer can then use hand tools to form the model by carving, shaping, and joining additional material. In this paper, a broken and damaged gear wheel of rotating machinery have been taken. This damaged model is scanned, then gear is reconstructed in CATIA V5 software and exact model of gear wheel is formed. This model is then printed by using 3D printing machine (uPrint SE Plus). Hence, by integration of reverse engineering and RP techniques, the gear model is prepared which can be used in rotatory machinery or casted for more numbers if required.

The 3D printing is popularly known as an Additive Manufacturing (AM) technology. In this process, a three-dimensional object is created by laying down successive layers of a material. In the recent years, this revolutionary method is one of the most eye-catching technological innovations. In addition, this technology has numerous potential applications in various industries. As a result, this process has a great technological and economical influence on nation’s growth. This current paper presents rapid prototyping, rapid manufacturing and the latest technologies available to fabricate 3D components in particular to engineering components. In case of electronic Industries, products such as sensors and switches have been made using 3D printing technology Optimization of printing parameters during 3D printing makes a component with improved physical and mechanical properties. As compared to conventional manufacturing technologies such as melting, casting, rolling, forging, etc., AM technologies produces materials with low cost production. An attempt has also been made to study the influence of AM and its direct impact on Indian GDP. Moreover, this detailed analysis would benefit various Indian academic, research institutes, manufacturing industries, etc.

Fused Deposition Modelling is one of the most widely used Additive Manufacturing technologies for various engineering applications. The present work investigated the aesthetics of the cube. In FDM process of printing, one of the major problems faced in printing the objects, specifically the cylindrical objects is the non-sticking of the preliminary layers of the molten filament on to the hot bed. There are other serious problems which occur while printing they are under extrusion, over extrusion of filament from heated printing nozzle, gaps occurring in the top layers of the printed object, stringing or oozing of the extra filament from the heated nozzle, overheating of print bed, Layer shifting, layer separation and splitting, grinding filament, clogged extruder, extruder stopping in the middle of printing process, gaps between infill and outline, etc. In this study, the above-mentioned problems are observed and identified through Pareto analysis that on the machine, the non-sticking of the preliminary layers to the hot bed occurred more, thus solutions are provided to avoid this problem which in turn has helped to reduce various other problems occurring while printing the 3D objects.

Bioprinting, an extension of traditional 3-D printing is the computer-aided additive manufacturing of cells, tissues, and scaffolds to create organs. It has emerged as the most innovative solution to the healthcare catastrophe of organ shortage and transplantation. Bioprinting makes use of rapid prototyping (RP) technology to print cells and biomaterials individually or in tandem, one layer over the other, producing 3-D tissue-like structures which can be reorganized and regrouped together to form vascularized organs. This review paper, sheds light on the current state of the art of bioprinting technology, various bioprinters used and focuses on the potential applications of bioprinted tissues in regenerative medicine. Challenges faced, limitations and future prospects of the technology have also been presented.

This paper discusses the development of a complete turnkey system to measure, design, and manufacture customized insoles. An optical foot measuring technology has been developed and used to detect the dimensions as well as the plantar pressure distribution of the foot pair instantly. A 3D CAD model of the insole is automatically generated followed by simple adjustments based on a certified medical professional’s diagnosis. The generated pair of customized insole models are joined together by their edges to form a single piece for easy manufacturing and easily separable once fabricated. The fabrication is done by Material Extrusion (ME) process using PETG (a modified version of PET) material in a custom built machine. In this paper, it is discussed in detail about the Foot Measurement Apparatus (FMA), Design approach, and Fabrication using Additive Manufacturing (AM) process.

Selective laser sintering (SLS) permits the fast, flexible, cost-efficient, and easy production of prototypes of required shape and size by using powder-based material. The physical prototype for design verification and working analysis is done directly on CAD tools. In SLS process optimization of influenced parameters will contribute to save time and material. In this study, optimal SLS process parameters by changing the layer thickness, bed temperature, and part orientation for hardness and ultimate tensile strength for the intended specimen by using Polyamide and also evaluate the mechanical behavior by using Vickers hardness tester and Ultimate tensile machine. The tests were conducted conferring to the Taguchi design of L9 orthogonal array at various combinations of process parameters and statistical optimization technique. Analysis Of Variance (ANOVA) was used to determine the optimal levels and percentage of influence of each parameter. The results postulate that the bed temperature is the main key factor followed by the part orientation and layer thickness for optimal value of the hardness and ultimate tensile strength of the SLS processed. This optimized value serves as a data base for the industries.

Vertebral Compression Fractures refer to the collapse of a vertebral body under excessive trauma to the spine. The surgical procedure to relieve pain and restore the normal height of the vertebral body is called vertebroplasty, in which a small amount of cement is injected into the spine. The problem with vertebroplasty is that the amount of cement injected is not accurate and leads to leakage into discs, which may develop into adjacent vertebral fractures. The current study aims at assessing the stress incurred on the adjacent vertebrae after vertebroplasty and the accurate cement levels required. The data in the form of CT images of the spine were acquired from a normal subject. A three-Dimensional model was generated by identifying the Regions of Interest (T11-L3), after performing volume and surface rendering techniques using Mimics and 3-MATIC. A force of 600 N was applied to the vertebrae for varying conditions of Bone Mineral Density (BMD), and the stress levels were calculated individually. Then, three fractures were induced at L1 and the corresponding 3-D models were generated. The stress levels on the fractured spine for forces of 600, 1200 and 1800 N were assessed. To assess the conditions after vertebroplasty, cement was injected in the fractured spine using Boolean Operations, which helped in optimizing the cement level. Results showed that the amount of cement required for the three cases were 4.5631, 5.5771 and 6.5849 mL respectively. Stress levels for the cement injected spine were analyzed, and were found to be much lesser than the stress incurred in the fractured cases with similar BMD. Among the adjacent vertebrae L2 was found to have a higher stress. Thus, this work seems to be clinically highly relevant in estimating the exact amounts of cements to be injected for different fracture cases thereby avoiding excessive cement leakage into the discs.

Functionally graded materials (FGMs) are superiorly engineered as well as natural materials with customized properties. These materials offer a variety of advantages over conventional materials in specific engineering applications. High strength, improved ductility, superior mechanical properties and enhanced surface properties are some advantages of FGMs when compared to homogeneous materials of the same type. Engineered FGMs have intrigued numerous researchers in recent years. These materials were conceived as thermal obstruction materials for various critical applications. These are increasingly being employed for numerous conventional as well as advanced applications. Many methods are utilized in developing FGMs possessing specific advantages and disadvantages. This article reviews current trends and developments of functionally graded materials (FGMs). Techniques to attain gradation especially structural and functional are emphasized in the current work. A few real life illustrations are discussed to present a glimpse of different FGM fabrication strategies to the readers.

Rapid prototyping (RP) is an innovating additive technology for creating functional prototypes and physical models directly from CAD model. Rapid Tooling (RT) is typically used to describe a process which either uses a Rapid Prototyping (RP) model as a pattern to create a mold quickly or uses the Rapid Prototyping process directly to fabricate a tool for a limited volume of prototypes. In this work, ABS electrode was metalized by electroless copper coating to make the RP electrode conductive. Applying a thin coating of copper to prototyped parts by electroless metallization has provided direct method from model to tool. Fused deposition modeling (FDM) process of rapid prototyping is employed to develop the electrode for electro-discharge machining (EDM). This revolutionary approach offer both designers and manufacturers attractive advantages of time compression and cost reduction. Time saving is of vital significance in production of EDM electrode for the fabrication of moulds and dies. The performance of these new type of electrode were compared with those obtained conventionally in term of, Surface Roughness (Ra), Tool Wear Rate (TWR), Working Time, Material Removal Rate (MRR) by using input parameters such as discharge Current, discharge Time, and discharge Voltage.

Premature failure of the components subjected to high temperature application has been a concern for last three decades now. Surface engineering is now an established approach to enhance component life for such application. A new approach; Additive manufacturing is gaining importance now a days. Additive Manufacturing, an incremental layer-by-layer manufacturing of components, has gained popularity as a possible option for producing fully dense metallic components in small span of time and creating its path in a constantly growing number of industries, such as aircrafts, military, automobile, medical, and architecture. The current review article includes the fundamentals of processes and introduces few metallic alloys which are presently available for layered manufacturing. The significance and prospective utility of the processes has been discussed with emphasis on mechanical properties like ultimate tensile strength and yield strength.

Metal based additive manufacturing (AM) techniques are continuously adopted by aerospace, automobile, defense, and healthcare industries. The primary concern for the components used in these applications is high precision. Despite being able to produce complex shapes, they lack in precision due to the distortions in shape and size of the part during and after fabrication. Distortion is the deviation of the part from its actual shape or dimension. Eventually, shape deviation has an unfavorable effect on the part functional performance which will hinder their use for critical technological applications. Even though, the temperature gradients during the process build affect these errors; they need to be studied in detail to fix the causation of these errors. In this paper, we review and classify the causation for shape and size distortion that occurs in metal additive processes. The approach to classification is multi-faceted and are based on the geometry of the fabricated part, the material used, process-related parameters, part orientation and physical phenomenon that occurs during the process. This work would help understand the root cause of distortion in major commercially successful metal AM processes and eliminate the need for costly trials.

Laser Metal Deposition (LMD), an additive manufacturing technique, is described here as an alternate for conventional manufacturing process to build aerospace components. Traditional milling of thin-walled, ribbed-, lightweight, high-valued Titanium structures generate machining wastes as high as 95%. This paper presents an LMD system setup along with an adapted manufacturing process chain for fabrication of near-net shaped Ti–6Al–4V components. Demonstrator parts built using the system setup are then shown.