Rapid Prototyping Techniques Research Articles

Grey relational analysis based optimization of process parameters for efficient performance of fused deposition modelling based 3D printer

Rapid prototyping techniques such as three-dimensional (3D) printing have rapidly gained popularity in industry since material layers are added rather than removed. Additive manufacturing creates objects from 3D CAD model data by layering materials, thus saving time and money. Fused deposition modelling (FDM) is the most often utilized additive manufacturing technology. To find the best parameters simultaneously affecting tensile strength, flexural strength, and wear resistance, this research aims to make use of grey relational analysis (GRA). In this investigation, the effect of different combinations of layer height, extruder temperature, infill percentage and print speed on the three mechanical properties is examined in depth. GRA optimization is used to find the ideal design factor levels for achieving the lowest wear rate while still providing the maximum possible tensile and flexural strength for the data obtained for sixteen experiments as per L16 orthogonal array. It is crucial to do Analysis of Variance (ANOVA) analysis in order to figure out the parameter contribution ratios. The grey relational grade (GRG) for any combination can be predicted quite accurately using regression analysis. The findings of the confirmation experiments demonstrated that the information gleaned from regression analysis is in line with that acquired from the experiments themselves.

From Point Cloud To Video Projection Mapping: Knowing Modern Architecture By Using Light Projection

Abstract The ClusterLab HeModern of the Università Iuav di Venezia has been working in recent years on the study, knowledge and conservation of 20th century architecture. This interdisciplinary research group (History of Architecture, Geomatics, Building Technology, Restoration Project) intends to investigate how to analyse and evaluate the state of conservation of the materials of which the modern architectural cultural heritage is composed by identifying specific application protocols for intervention, preservation and valorisation. In 2018, the collaboration between the above-mentioned ClusterLab, the LéaV of the Ecole nationale supérieure d’architecture in Versailles and the Archivio del Moderno of the Accademia di architettura in Mendrisio - Università della Svizzera italiana, culminated in the identification of the works and career of André Bloc as a case study. In the context of this study, the Tour, the Engineer’s posthumous work, was selected to serve as a sample for research on the methods of communication of the contents of the architecture, the survey procedures used and the elaborations obtained. So, after the survey campaign, which took place via topographic, laser scanning and photogrammetric methods, two different levels of restitution were conceived: the first, made according to the canonical graphic paper methods, represents the procedural and surveying information, the material characterisation and the state of decay; the second elevates the same contents by applying them to physical reality. In this phase, the research focused on the possibility of making the different projects collaborate through the technique of rapid prototyping and video projection mapping. This particular form of augmented reality was used to enrich, through the mediation of light projections, the sensory perception of the observers by adding more information and emphasising those of greatest interest, proposing an alternative way of storytelling. In fact, unlike other forms of augmented reality, in the case of video projection mapping, the observer has the possibility to interact continuously with the physical reality, whose character is static, while the transmission of data is dynamic and can range in heterogeneity. The elaborations produced were presented in form of a museum exhibit at the international conference “Arti e architettura. Il contributo di André Bloc 1950-1970”, which took place in the exhibition rooms of the Università Iuav di Venezia.

Design and Analysis of a Low-Cost Electronically Controlled Mobile Ventilator, Incorporating Mechanized AMBU Bag, for Patients during COVID-19 Pandemic.

The outbreak of novel COVID-19 has severely and unprecedentedly affected millions of people across the globe. The painful respiratory distress caused during this disease calls for external assistance to the victims in the form of ventilation. The most common types of artificial ventilating units available at the healthcare facilities and hospitals are exorbitantly expensive to manufacture, and their number is fairly inadequate even in the so-called developed countries to cater to the burning needs of an ever-increasing number of ailing human subjects. According to available reports, without the provision of ventilation, the novel COVID-19 patients are succumbing to their ailments in a huge number of cases. This colossal problem of the availability of ventilator units can be addressed to a great extent by readily producible and cost-effective ventilating units that can be used on those suffering patients during an acute emergency and in the absence of conventional expensive ventilators at hospitals and medical care units. This paper has made an attempt to design and simulate a simple, yet effective, mechanized ventilator unit, which can be conveniently assembled without a profuse skillset and operated to resuscitate an ailing human patient. The stepper motor-controlled kinematic linkage is designed to deliver the patient with a necessitated discharge of air at optimum oxygen saturation through the AMBU bag connected in a ventilation circuit. With the associated code on MATLAB, the motor control parameters such as angular displacement and speed are deduced according to the input patient conditions (age group, tidal volume, breathing rate, etc.) and thereafter fed to the controller that drives the stepper motor. With a proposed feedback loop, the real-time static and dynamic compliance, airway resistance values can be approximately determined from the pressure variation cycle and fed to the controller unit to adjust the tidal volume as and when necessary. The simplistic yet robust design not only renders easy manufacturability by conventional and rapid prototyping techniques like 3D printing at different scales but also makes the product easily portable with minimal handling difficulty. Keeping the motto of Health for All as envisioned by the WHO, this low-cost indigenously engineered ventilator will definitely help the poor and afflicted towards their right to health and will help the medical professionals buy some time to manage the patient with acute respiratory distress syndrome (ARDS) towards recovery. Moreover, this instrument mostly includes readily available functional units having standard specifications and can be considered as standard bought-out items.

3D Printed PCB Microfluidics.

The combination of printed circuit boards (PCB) and microfluidics has many advantages. The combination of electrodes, sensors and electronics is needed for almost all microfluidic systems. Using PCBs as a substrate, this integration is intrinsic. Additive manufacturing has become a widely used technique in industry, research and by hobbyists. One very promising rapid prototype technique is vat polymerization with an LCD as mask, also known as masked stereolithography (mSLA). These printers are available with resolutions down to 35 µm, and they are affordable. In this paper, a technology is described which creates microfluidics on a PCB substrate using an mSLA printer. All steps of the production process can be carried out with commercially available printers and resins: this includes the structuring of the copper layer of the PCB and the buildup of the channel layer on top of the PCB. Copper trace dimensions down to 100 µm and channel dimensions of 800 µm are feasible. The described technology is a low-cost solution for combining PCBs and microfluidics.

Digitising prosthetics: Clinical series

Loss of any part of the body is seen mostly due to trauma, diseases or congenital malformations which causes psychological trauma along with functional, and esthetic impairment. Amputed finger can be surgically reconstructed but when not feasible the patient reports to a prosthetist for replacement of the lost part. The patient’s expectations must be met by the prosthetist by mimicking the opposite digit as closely as possible which helps regains the patient’s lost confidence. This article proposes a technique for rehabilitation of an amputated finger using Rapid prototyping technique as compared to the conventional technique which is time consuming, requires manual skills, lacks precision and finesse making digitally fabricated prosthetic digit a reality.

Evaluation of polymeric 3D printed adhesively bonded joints: effect of joint morphology and mechanical interlocking

PurposeThe purpose of this paper is to evaluate and exploit the combination of additive manufacturing polymeric technology and structural adhesives. The main advantage is to expand the maximum dimension of the 3D printed parts, which is typically limited, by joining the parts with structural adhesive, without losing strength and stiffness and keeping the major asset of polymeric 3 D printing: freedom of shape of the system and low cost of parts.Design/methodology/approachThe materials used in the paper are the following. The adhesive considered is a commercial inexpensive acrylic, quite similar to superglue, applicable with almost no surface preparation and fast curing, as time constraint is one of the key problems that affects industrial adhesive applications. The 3D printed parts were in acrylonitrile butadiene styrene (ABS), obtained with a Fortus 250mc FDM machine, from Stratasys. The work first compares flat overlap joint with joints designed to permit mechanical interlocking of the adherends and then to a monolithic component with the same geometry. Single lap, joggle lap and double lap joints are the configurations experimentally characterized following a design of experiment approach.FindingsThe results show a failure in the substrate, due to the low strength of the polymeric adherends for the first batch of typical bonded configurations, single lap, joggle lap and double lap. The central bonded area, with an increased global thickness, never does fail, and the adhesive is able to transfer the load both with and without mechanical interlocking. An additional set of scarf joints was also tested to promote adhesive failure as well as to retrieve the adhesive strength in this application. The results shows that bonding of polymeric AM parts is able to express its full potential compared with a monolithic solution even though the joint fails prematurely in the adherend due to the bending stresses and the notches present in the lap joints.Research limitations/implicationsBecause of the 3D printed polymeric material adopted, the results may be generalized only when the elastic properties of the adherends and of the adhesive are similar, so it is not possible to extend the findings of the work to metallic additive manufactured components.Practical implicationsThe paper shows that the adhesives are feasible way to expand the potentiality of 3 D printed equipment to obtain larger parts with equivalent mechanical properties. The paper also shows that the scarf joint, which fails in the adhesive first, can be used to extract information about the adhesive strength, useful for the designers which have to combine adhesive and additive manufactured polymeric parts.Originality/valueTo the best of the researchers’ knowledge, there are scarce quantitative information in technical literature about the performance of additive manufactured parts in combination with structural adhesives and this work provides an insight on this interesting subject. This manuscript provides a feasible way of using rapid prototyping techniques in combination with adhesive bonding to fully exploit the additive manufacturing capability and to create large and cost-effective 3 D printed parts.

A Thermocycler Using a Chip Resistor Heater and a Glass Microchip for a Portable and Rapid Microchip-Based PCR Device.

This study proposes a rapid and inexpensive thermocycler that enables rapid heating of samples using a thin glass chip and a cheap chip resistor to overcome the on-site diagnostic limitations of polymerase chain reaction (PCR). Microchip PCR devices have emerged to miniaturize conventional PCR systems and reduce operation time and cost. In general, PCR microchips require a thin-film heater fabricated through a semiconductor process, which is a complicated process, resulting in high costs. Therefore, this investigation substituted a general chip resistor for a thin-film heater. The proposed thermocycler consists of a compact glass microchip of 12.5 mm × 12.5 mm × 2 mm that could hold a 2 μL PCR sample and a surface-mounted chip resistor of 6432 size (6.4 mm × 3.2 mm). Improving heat transfer from the chip resistor heater to the PCR reaction chamber in the microchip was accomplished via the design and fabrication of a three-dimensional chip structure using selective laser-induced etching, a rapid prototyping technique that allowed to be embedded. The fabricated PCR microchip was combined with a thermistor temperature sensor, a blower fan, and a microcontroller. The assembled thermocycler could heat the sample at a maximum rate of 28.8 °C/s per second. When compared with a commercially available PCR apparatus running the same PCR protocol, the total PCR operating time with a DNA sample was reduced by about 20%.

Thermal analysis of fused deposition modeling process based finite element method: Simulation and parametric study

Fused deposition modeling (FDM) is an advanced additive manufacturing (AM) method for rapid prototyping technique and to produce functional components with complex geometry. However, the process is mostly appropriate to polymer-based raw materials for several fields of application. In this study, a 3-D computational model is developed to analyze the transient heat transfer problem and investigate the inter-layer adhesion behavior, which affects the mechanical behavior of the final part. The developed model is validated based on published experimental and analytical data. The numerical model is utilized to predict the temperature evolution in the interface region between layers. The time history of temperature is coupled with a mathematical model describing the bonding potential to predict the bonding formation. In addition, the developed model is combined with design exploration tools to investigate the relationship between key process parameters and their impact on the output variables using design of experiment (DEO) and response surface methods. Moreover, due to the 3-D nature of the developed model, it could be coupled with a structural computational tool for further thermomechanical analysis.

Development of a didactic demonstrator for flow-induced noise mechanisms and mitigation technologies.

A small didactic wind tunnel demonstrator has been designed and manufactured at the von Karman Institute for Fluid Dynamics to illustrate the physical principles at stake in flow-induced noise generation, offer an audible perception of the effectiveness of noise-mitigation strategies, and serve as a practical test bench for aeroacoustic education and research. Seven mitigation technologies are embedded in a single facility, which addresses the noise generation by an airfoil, noise propagation in a duct, and noise transmission through a flexible panel. A challenging objective of this facility was to offer a perceptible impression of various aeroacoustic noise mechanisms at low flow speeds and a live assessment of the effectiveness of noise-reduction technologies. Different approaches combining multiple microphones, advanced signal-processing techniques, and real-time audio feedback have been implemented to this end. A digital twin has been developed to assist the design of the facility and test the concepts implemented in it. The results establish that the demonstrator enables a clear perception of the effectiveness of the noise-mitigation technologies. The facility is also suitable for fast and inexpensive preliminary investigations of future noise-reduction concepts, taking advantage of rapid prototyping techniques.

Geometric definition, rapid prototyping, and cutting force analysis of cylindrical milling tools with arbitrary helix angle variations

In this work, a method is developed for geometric definition and analysis of cylindrical milling tools having various free-form variations of helix angle. The method is based on replicating a position vector on each cutting edge to generate a point set for the whole tool envelope using piece-wise rotation and magnification matrices which are varied according to mathematical laws describing the intended variable shape of the tool. The computed point sets are applied in additive manufacturing of samples of such tools having non-conventional shape features by transforming the point sets to stereolithography formats that are sliced to guide the 3D-printing processes. This manufacturing route that simplifies the realization of arbitrary helix profiles on milling tools is a major contribution of this work since such tools are gaining popularity for their passive damping of vibrations and reduction of cutting forces but are notoriously difficult to manufacture, limiting their exploitation. Analyses are shown about the effects of the considered variable profiles on milling cutting force. These suggest that cutting forces can be greatly suppressed by the proposed free-form helix angle variations. For example, relative to a conventional fixed helix tool of same mean helix angle, the innovative tools recorded 40.33%–84.42% and 60.53%–67.81% force reductions at axial depths of cut of 1 and 5 mm. This demonstrates that innovative variable tool profiles which can be realized through the simplified rapid prototyping technique are promising for advanced sustainable manufacturing of parts with preferred surface conditions.

3D printable biomaterials for dental restoration: A systematic review

This article presents in a unified way the evolution and current scenario of various rapid prototyping techniques used in dentistry and different 3D printable materials used in the amalgamation of the high-level dental composite framework. The article briefly describes the most preferred 3D printing techniques used for printing novel and conventional biomaterials, mainly (i) stereolithography, (ii) digital light processing, (iii) fused deposition modeling, and (iv) selective laser sintering. The review also discusses various types of 3D printable biomaterials used in digital dentistry, including thermoplastics, ceramics, metals in detail. Various kinds of printable biomaterials, along with their advantages, fabrication process, and primary references, are presented in tabular form. Further, the applications of additive manufacturing processes in dental prosthodontics, including the fabrication of crowns, bridges, and dentures, are also discussed. This technical review has primarily two objectives: (i) dental professionals can select the most suitable additive manufacturing technique and biomaterial for their end application (ii) identification of existing potential research gaps for the researchers and doctors working in this area.

Development of a Lizard-Inspired Wall-Climbing Robot Using Pressure Sensitive Adhesion

This paper presents the design, fabrication, and control of a quadruped wall-climbing robot. The robot’s kinematics is inspired by lizards, which use trot-gait for the locomotion. The key features of this robot are its pressure-sensitive adhesive (PSA) enabled adhesion and peeling mechanism and the locomotion controller capable of straight and turning motion. We obtained an average vertical climbing speed of 1.35 cm/s without payload and 1.25 cm/s with a payload of 20 gm. Rapid prototyping techniques namely 3D-printing and 2D-LASER cutting are used to fabricate the entire structure of the robot, allowing easy replication of the entire robot in case a swarm of such robots is needed. This paper also reports climbing stability criteria for the developed robot expressed in terms of the pitching moment. We envisage that the developed robot can be deployed in surveillance, reconnaissance, cleaning, and repairing applications.

Digital dental models in orthodontics: A review

Digital 3 dimensional (3D) dental models are considered one of the most important advancements in modern dental history. Digital dental models are used in diagnosis, treatment planning, and appliance production phases in orthodontics. The present technology of digital dental models reached, and in some points, exceeded the plaster models' accuracy. The use of digital models with CBCT images and rapid prototyping techniques brought the possibility of new treatment techniques, some of which are considered as the future of modern orthodontics. This article aims to review the current use and success of digital 3D models in orthodontic practice.

Additive and subtractive rapid prototyping techniques: a comparative analysis of FDM & CNC processes

Additive and subtractive rapid prototyping techniques: a comparative analysis of FDM & CNC processes

Use of 3-D Printed Models for Implant Placement - A Case Series

Long-term stability of a dental implant depends on various factors, one among them is proper position within the alveolar bone. Pre-operative thorough examination of the surgical site is preliminary step while planning dental implants. Conventional techniques such as Intra-Oral Periapical Radiograph and Ortho Pantamogram sometimes not sufficient and clinical scenario always surprises the surgeon. Later advent of Cone-Beam Computed Tomography alleviated this problem to some extent but there are some clinical situations such as resorbed ridge where better visualisation is needed. This led to the innovation of rapid prototyping techniques for the fabrication of three-dimensional complex structures. This technology has numerous applications from the development of an instrument, 3-D printed anatomical models to the fabrication of 3-D printed tissues for regeneration procedures. A 3-D printed model is much more useful than plaster models in many aspects such as demonstrating anatomical structures, better treatment planning, and better understanding for the patient. Hence, this case series focuses on the use of 3-D printed models in the placement of dental implants.

Combination of Ceramic Laser Micromachining and Printed Technology as a Way for Rapid Prototyping Semiconductor Gas Sensors.

The work describes a fast and flexible micro/nano fabrication and manufacturing method for ceramic Micro-electromechanical systems (MEMS)sensors. Rapid prototyping techniques are demonstrated for metal oxide sensor fabrication in the form of a complete MEMS device, which could be used as a compact miniaturized surface mount devices package. Ceramic MEMS were fabricated by the laser micromilling of already pre-sintered monolithic materials. It has been demonstrated that it is possible to deposit metallization and sensor films by thick-film and thin-film methods on the manufactured ceramic product. The results of functional tests of such manufactured sensors are presented, demonstrating their full suitability for gas sensing application and indicating that the obtained parameters are at a level comparable to those of industrial produced sensors. Results of design and optimization principles of applied methods for micro- and nanosystems are discussed with regard to future, wider application in semiconductor gas sensors prototyping.

Understanding the Effect of Energy Density and Formulation Factors on the Printability and Characteristics of SLS Irbesartan Tablets—Application of the Decision Tree Model

Selective laser sintering (SLS) is a rapid prototyping technique for the production of three-dimensional objects through selectively sintering powder-based layer materials. The aim of the study was to investigate the effect of energy density (ED) and formulation factors on the printability and characteristics of SLS irbesartan tablets. The correlation between formulation factors, ED, and printability was obtained using a decision tree model with an accuracy of 80%. FT-IR results revealed that there was no interaction between irbesartan and the applied excipients. DSC results indicated that irbesartan was present in an amorphous form in printed tablets. ED had a significant influence on tablets’ physical, mechanical, and morphological characteristics. Adding lactose monohydrate enabled faster drug release while reducing the possibility for printing with different laser speeds. However, formulations with crospovidone were printable with a wider range of laser speeds. The adjustment of formulation and process parameters enabled the production of SLS tablets with hydroxypropyl methylcellulose with complete release in less than 30 min. The results suggest that a decision tree could be a useful tool for predicting the printability of pharmaceutical formulations. Tailoring the characteristics of SLS irbesartan tablets by ED is possible; however, it needs to be governed by the composition of the whole formulation.

Mathematical Modeling and Optimization of Fused Filament Fabrication (FFF) Process Parameters for Shape Deviation Control of Polyamide 6 Using Taguchi Method.

Fused filament fabrication (FFF) is a layer-by-layer additive manufacturing (AM) process for producing parts. For industries to gain a competitive advantage, reducing product development cycle time is a basic goal. As a result, industries’ attention has turned away from traditional product development processes toward rapid prototyping techniques. Because different process parameters employed in this method significantly impact the quality of FFF manufactured parts, it is essential to optimize FFF process parameters to enhance component quality. The paper presents optimization of fused filament fabrication process parameters to improve the shape deviation such as cylindricity and circularity of 3D printed parts with the Taguchi optimization method. The effect of thickness, infill pattern, number of walls, and layer height was investigated as variable parameters for experiments on cylindricity and circularity. The MarkForged® used Nylon White (PA6) to create the parts. ANOVA and the S/N ratio are also used to evaluate and optimize the influence of chosen factors. As a result, it was concluded that the hexagonal infill pattern, the thickness of 5 mm, wall layer of 2, and a layer height of 1.125 mm were known to be the optimal process parameters for circularity and cylindricity in experiments. Then a linear regression model was created to observe the relationship between the control variables with cylindricity and circularity. The results were confirmed by a confirmation test.

Biting Force and chewing efficiency of Conventional and CAD/CAM complete dentures. A Cross-over Study

Background: Many studies reported using CAD/CAM technology in implant-supported prostheses. However, few studies reported its use in complete dentures. The aim of this study is to compare the Maximum Biting Force (MBF) and chewing efficiency of complete dentures fabricated by conventional, rapid prototyping and milling techniques. Materials and Methods: This is a clinical study with a cross-over design where 27 completely edentulous participants were divided in a random order into 3 equal groups as 1. received conventional complete denture 2. received 3D printed complete dentures 3. received milled complete dentures. Assessment of MBF was performed after denture insertion at 1 week, 1 month and 3 months, using Flexiforce A 301® force sensor. Mixing ability test was used to assess chewing efficiency 3 months after denture insertion. Repeated measure ANOVA test and Paired sample t-test were used with P ≤ 0.05 level of significance. Results: Regarding the MBF, there was a statistically significant increase (p < 0.001) in the MBF at 1w, 1m and 3m follow-up periods in all three groups. There was a statistically significant difference in chewing efficiency between 5, 10, 20, 30 and 50 strokes and between the three groups (p < 0.001). MBF and chewing efficiency increased significantly (p < 0.001) in Printed CAD/CAM and Milled CAD/CAM groups when compared to conventional complete dentures. Milled group showed a statistically significant improvement (p < 0.001) in MBF and chewing efficiency when compared to Printed group. Conclusion: The CAD/CAM fabricated dentures showed better results in terms of MBF and chewing efficiency compared to conventional complete denture.

Correlation of Panoramic Radiography, Cone-Beam Computed Tomography, and Three-Dimensional Printing in the Assessment of the Spatial Location of Impacted Mandibular Third Molars.

The development of radiology, rapid prototyping techniques, and the increasingly common use of 3D printing in dentistry inspires the use of these techniques to improve diagnostic and therapeutic processes. This study aimed to conduct a retrospective comparative analysis of dental panoramic radiographs, cone-beam computed tomography, and 3D printing in preoperative assessment of the procedure’s difficulty. Thirty clinical cases with a high degree of difficulty were selected, and based on evaluation with CBCT, a virtual 3D model of the region of surgical procedure was created, which was then printed using a 3D printer. The comparative analysis included the linear measurements performed in dental panoramic radiographs, cone-beam computed tomography, and 3D models in a preoperative assessment of the degree of retention and difficulty of impacted mandibular third molars in the mandible. Linear measurements performed on dental panoramic radiographs were significantly lower than in cone-beam computed tomography and 3D models. No statistically significant differences were obtained in linear measurements between 3D models and cone-beam computed tomography images except for the measurement of the lingual lamina thickness; however, due to the insignificant differences in measurements, with a mean of only 80 µm, the elective procedure of removal of the impacted third molar in the mandible may be safe.