Additive manufacturing of metallic components – Process, structure and properties

Leu-M

https://www.tandfonline.com/doi/pdf/10.1088/1468-6996/16/3/033502

A review on powder-based additive manufacturing for tissue engineering: selective laser sintering and inkjet 3D printing

In new product development, time to market (TTM) is critical for the success and profitability of next generation products. When these products include sophisticated electronics encased in 3D packaging with complex geometries and intricate detail, TTM can be compromised - resulting in lost opportunity. The use of advanced 3D printing technology enhanced with component placement and electrical interconnect deposition can provide electronic prototypes that now can be rapidly fabricated in comparable time frames as traditional 2D bread-boarded prototypes; however, these 3D prototypes include the advantage of being embedded within more appropriate shapes in order to authentically prototype products earlier in the development cycle. The fabrication freedom offered by 3D printing techniques, such as stereolithography and fused deposition modeling have recently been explored in the context of 3D electronics integration - referred to as 3D structural electronics or 3D printed electronics. Enhanced 3D printing may eventually be employed to manufacture end-use parts and thus offer unit-level customization with local manufacturing; however, until the materials and dimensional accuracies improve (an eventuality), 3D printing technologies can be employed to reduce development times by providing advanced geometrically appropriate electronic prototypes. This paper describes the development process used to design a novelty six-sided gaming die. The die includes a microprocessor and accelerometer, which together detect motion and upon halting, identify the top surface through gravity and illuminate light-emitting diodes for a striking effect. By applying 3D printing of structural electronics to expedite prototyping, the development cycle was reduced from weeks to hours.

3D Printing for the Rapid Prototyping of Structural Electronics

The rapid prototyping has been developed from the 1980s to produce models and prototypes until the technologies evolution today. Nowadays, these technologies have other names such as 3D printing or additive manufacturing, and so forth, but they all have the same origins from rapid prototyping. The design and manufacturing process stood the same until new requirements such as a better integration on production line, a largest series of manufacturing or the reduce weight of products due to heavy costs of machines and materials. The ability to produce complex geometries allows proposing of design and manufacturing solutions in the industrial field in order to be ever more effective. The additive manufacturing (AM) technology develops rapidly with news solutions and markets which sometimes need to demonstrate their reliability. The community needs to survey some evolutions such as the new exchange format, the faster 3D printing systems, the advanced numerical simulation or the emergence of new use. This revie...

Additive manufacturing technologies: state of the art and trends

In additive manufacturing (AM) processes, the tessellation of CAD model and the slicing procedure are the significant factors resulting unsatisfactory surface quality, where the topics related to surface roughness have been a key issue in this regard. In this paper, analytical models which have been presented to express surface roughness distribution in fused deposition modeling (FDM) are assessed according to the variations in surface build angle by considering the main factors which crucially affect surface quality. Analytical models are verified by implementation and comparison with empirical data derived from the comprehensive FDM fabricated test part. Finally, the most accurate model for estimation of surface roughness in the process planning stage for optimization of effective parameters have been introduced upon calculating the mean absolute percentage error (MAPE) as performance criteria of each model in various equal ranges.

Evaluation of analytical modeling for improvement of surface roughness of FDM test part using measurement results

Increasing competition in global markets is exerting intense pressure on companies to trim their product cycles continuously. As delivery times and costs of tools are on a downward trend, the modern tool manufacturer is under pressure to produce tools quickly, accurately and at a lower cost. Reducing the time to produce prototypes is a key to speed up the development of new products. Rapid tooling (RT) with particular regard to injection mould fabrication using rapid prototyping (RP) technology of Stereolithography (SL) may lead to savings in cost and time. In this paper, SL is used to directly build rapid injection mould tools for short run production. SL tools have been evaluated to analyse the maximum number of successful injections and quality of performance. SL epoxy tools were able to resist the injection pressure and temperature and 500 injections were achieved. The tool failure mechanisms during injection are investigated and tool failure either occurs due to excessive flexural stresses, or because of excessive shear stresses.

Rapid tooling analysis of Stereolithography injection mould tooling

To improve the surface roughness of parts fabricated using fused deposition modeling, modeling of the surface roughness distribution is used before the fabrication process to enable more precise planning of the additive manufacturing process. In this paper, a new methodology based on radial basis function neural networks (RBFNNs) is proposed for estimation of the surface roughness based on experimental results. The effective variables of the RBFNN are optimized using the imperialist competitive algorithm (ICA). The RBFNN-ICA model outperforms considerably comparing to the RBFNN model. A specific test part capable of evaluating the surface roughness distribution for varied surface build angles is built. To demonstrate the advantage of the recommended model, a performance comparison of the most well-known analytical models is carried out. The results of the evaluation confirm the capability of more fitted responses in the proposed modeling. The RBFNN and RBFNN-ICA models have mean absolute percentage error of 7.11% and 3.64%, respectively, and mean squared error of 7.48 and 2.27, respectively. The robustness of the network is studied based on the RBFNN’s effective variables evaluation and sensitivity analysis assessment for the contribution of input parameters. Finally, the comprehensive validity assessments confirm improved results using the recommended modeling.

Application of an RBF neural network for FDM parts' surface roughness prediction for enhancing surface quality

Purpose – Dimensional accuracy analysis of wax model created by room temperature vulcanization (RTV) silicone rubber molding to be used in investment casting is presented. The purpose of this paper is to discuss the effective parameters of dimensional accuracy in RTV tooling technique.Design/methodology/approach – After producing a pattern by stereolithography (SLA) and then creating the RTV silicone rubber mold by the SLA pattern, dimensional accuracy of wax models produced by RTV tool are analyzed. Design of experiments (DOE) using the Taguchi approach is used for analysis and determination of optimum condition.Findings – Experiments show that the dimensional accuracy in RTV technique is as accurate as in traditional molding. Hence, RTV tooling technique can be used in investment casting. Using Taguchi approach based on DOE, it was realized that the optimum condition to achieve acceptable accuracy is 35°C for mold temperature, 85°C for wax temperature, and −0.5 barG for vacuum pressure.Practical implica...

Dimensional accuracy analysis of wax patterns created by RTV silicone rubber molding using the Taguchi approach

A green method for the synthesis of gelatin/pectin stabilized palladium nano-particles has been described. These particles were prepared under green conditions without addition of any external reducing agent and ligand. All properties of the supported palladium particles on gelatin/pectin mixture were showed by UV–vis spectra and also by EDX, XRD, TEM and FESEM images. The synthesized palladium nanoparticles were studied in Mizoroki–Heck reaction between different aryl halides and n-butyl acrylate. The reaction was performed under solvent-free conditions and no complicated work up process was needed for the isolation of the nano-particles. Also the products were obtained in highly short reaction times with excellent yields.

A green method for the synthesis of gelatin/pectin stabilized palladium nano-particles as efficient heterogeneous catalyst for solvent-free Mizoroki–Heck reaction

Sadegh Rahmati

Papers

Evaluation of analytical modeling for improvement of surface roughness of FDM test part using measurement results

Rapid tooling analysis of Stereolithography injection mould tooling

Application of an RBF neural network for FDM parts' surface roughness prediction for enhancing surface quality

Dimensional accuracy analysis of wax patterns created by RTV silicone rubber molding using the Taguchi approach

A green method for the synthesis of gelatin/pectin stabilized palladium nano-particles as efficient heterogeneous catalyst for solvent-free Mizoroki–Heck reaction