Jet Material Research Articles

Influence of the Print Envelope Temperature on the Morphology and Tensile Properties of Thermoplastic Polyolefins Fabricated by Material Extrusion and Material Jetting Additive Manufacturing.

Additive manufacturing (AM) nowadays has become a supportive method of traditional manufacturing. In particular, the medical and healthcare industry can profit from these developments in terms of personalized design and batches ranging from one to five specimens overall. In terms of polymers, polyolefins are always an interesting topic due to their low prices, inert chemistry, and crystalline structure resulting in preferable mechanical properties. Their semi-crystalline nature has some advantages but are challenging for AM due to their shrinkage and warping, resulting in geometrical inaccuracies or even layer detaching during the process. To tackle these issues, process parameter optimization is vital, with one important parameter to be studied more in detail, the print envelope temperature. It is well known that higher print envelope temperatures lead to better layer adhesion overall, but this investigation focuses on the mechanical properties and resulting morphology of a semi-crystalline thermoplastic polyolefin. Further, two different AM technologies, namely material jetting (ARBURG plastic freeforming-APF) and filament-based material extrusion, were studied and compared in detail. It was shown that higher print envelope temperatures lead to more isotropic behavior based on an evenly distributed morphology but results in geometrical inaccuracies since the material is kept in a molten state during printing. This phenomenon especially could be seen in the stress and strain values at break at high elongations. Furthermore, a different crystal structure can be achieved by setting a specific temperature and printing time, also resulting in peak values of certain mechanical properties. In comparison, better results could be archived by the APF technology in terms of mechanical properties and homogeneous morphology. Nevertheless, real isotropic part behavior could not be managed which was shown by the specimen printed vertically. Hence, a sweet spot between geometrical and mechanical properties still has to be found.

BRDF representation in response to the build orientation in 3D-printed digital materials

Additively manufactured (AM) parts still lack a thorough understanding of their optical properties, particularly surface texture and reflectance characteristics at different viewing angles. This study examines the reflectance properties of material jetting (MJT) parts using bidirectional reflectance distribution functions (BRDFs). The visual appearance of the MJT parts was analyzed using a gonio-spectrophotometer at 328 unique incidence and viewing geometries for seven different wedge angles for build orientation (BO) from 0° to 90° at 15° intervals. The redundancy analysis (RDA) and principal component analysis (PCA) were used to study BO and to determine the prominent measurement geometries. The results indicate higher BOs resulted in more color and texture variation and rougher surfaces, with Sq 4.21 μm vertical compared to 1.42 μm for horizontal BOs. Furthermore, it affected the visual representation and parametric estimation of BRDF, where significantly lower luminance, more diffuse reflection, and less hue distribution were observed for all CMYK resins printed at higher BOs. Accordingly, vertically printed surfaces showed a wider near-to-specular luminance area than other BOs. An analysis of the bidirectional reflectance property suggests that a gonio-spectrophotometer can be embedded in the printing process and quality assurance in AM as a computationally efficient model.

Additive Manufacturing of High-Temperature Thermoplastic Polysulfone with Tailored Microstructure via Precipitation Printing.

Current additive manufacturing processes for polymers, including material extrusion, vat photopolymerization, material jetting, and powder bed fusion, have limitations in manufacturing high-temperature thermoplastics including narrow material selection, compromised mechanical properties, and potential degradation of materials during processing. Polysulfone (PSU) is a high-temperature thermoplastic with outstanding chemical resistance, flame retardancy, and toughness. However, besides injection molding, additive manufacturing of PSU has only been achieved through extrusion or solvent-cast three-dimensional (3D) printing without obtaining high mechanical properties. In this work, precipitation printing is applied to fabricate high-temperature thermoplastics such as PSU for the first time, where tailoring of the microstructure and mechanical properties is enabled through control of solvents and printing parameters. The printed PSU can either be dense and strong with 2.47 GPa Young's modulus and 70.6 MPa tensile strength or porous and highly anisotropic. After drying at a maximum temperature of 190 °C, both the printed dense and porous PSU samples have a glass-transition temperature of about 200 °C, which allows them to be used in high-temperature environments. Thus, precipitation printing provides an alternative approach to manufacture high-temperature thermoplastics like PSU with scalability and tailorable properties.

Three-dimension dithering and its effect on the interfacial strength of multi-material and emulated multi-material additive manufacturing processes

Multi-Material Additive Manufacturing (MMAM) offers the potential for superior functional parts by varying properties throughout a structure. Previous work has shown that the interface region of such MMAM parts has great importance on their overall strength. Most of these studies have focused on rigid–compliant interfaces within parts manufactured via material jetting (MJT). This work focuses, initially, on the creation of different interfacial geometries within functionally graded tensile bars by extending two dimensional dithering algorithms from the realm of image processing into the third dimension. It tests these dithered patterns, along with Schwarz P and Gyroid structures, across rigid–complaint MJT interfaces before further exploring the previously unaddressed question of how these different geometries affect interfacial strength across rigid–rigid interfaces for both UV cured materials, via MJT, and thermoplastic materials, via a new prototype electophotographic toner-based AM system. Within the MJT parts, the samples often failed inside the large regions of the more compliant material rather than at the interface itself. In addition, the interfacial length is shown to have more effect on the mechanical properties compared to interface pattern. However, the thermoplastic samples consistently failed within the interface region. The toughness of these thermoplastic parts increased with an increase in the connected surface area in the tensile direction between the largest regions of each of the two materials, with three dimensional random dithering over a 20 mm gradient length exhibiting the toughest interface overall (40.8% increase in the work at break when compared to a control sample with no special interfacial geometry). This work, therefore, provides a new emphasis to explore, within the context of the design of thermoplastic multi-material interfaces, geometries that increase this connected surface area.

Additive manufacturing of low-temperature co-fired ceramic substrates and surface conductors based on material jetting

Integrated manufacturing of ceramic substrates and surface conductors using 3D material jetting (MJ) technology is a novel additive manufacturing route for low-temperature co-fired ceramics (LTCC). This study evaluates the rheological and jetting properties of LTCC nanoceramic inks with varying solids contents. Ceramic inks with 35 % solid content were found to be the optimal choice with high particle concentration and Ohnesorge numbers (Oh) below 1. The fabrication process used two piezoelectric printheads to inject nanoceramic ink and nanosilver ink to create a ceramic substrate and a surface interdigital electrode (IDE). The substrate sintering shrinkage was 21.5 % and the surface IDE co-fired at the same shrinkage rate as the substrate thus ensuring all electrode pattern details. The electrode conductors demonstrated effective line widths of up to 0.21 mm. Microscopic characterisation of the interface between silver and substrate using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) confirmed the absence of significant elemental diffusion, and X-ray diffraction spectroscopy (XRD) results demonstrate that there is no second-phase generation, thus ensuring the effectiveness of the silver electrode. The ceramic substrates exhibit good thermal stability below 400 ℃ and have a coefficient of thermal expansion (∼ 4.1 ppm/℃) similar to that of silicon, indicating reliability in packaging. A microstrip patch antenna with the design frequency at 9–11 GHz was made through the same MJ procedure, which was experimentally measured to have a resonant frequency of 10.1 GHz, an S11 measurement of −24.6 dB, a simulated radiation efficiency of 88.01 %, and a high gain of up to 7.52 dB. Finally, a curved LTCC substrate with a radius of curvature of 50 mm and curved circuits was successfully fabricated using MJ technology. Interestingly, the curvature of the substrate maintained its original shape both before and after the sintering process, and the serpentine conductor pattern exhibited synchronous contraction, which implies the potential for developing a conformal LTCC utilizing MJ technology.

Comparative performance evaluation of microarchitected lattices processed via SLS, MJ, and DLP 3D printing methods: Experimental investigation and modelling

Additively manufactured mechanical metamaterials are gaining prominence in lightweight energy-absorption applications due to their exceptional mass-specific properties. Herein, we examine the energy absorption characteristics of micro-architected truss-, shell- and plate-lattice structures, namely, Octet, Kelvin, Gyroid, SC, BCC and FCC over a range of relative densities under quasi-static compression via both experiments and finite element analysis (FEA). Employing different 3D printing methods, namely, Digital Light Processing, Selective Laser Sintering and Material Jetting, the lattices were fabricated using PlasGray™ (photo-resin based plastic), PA12 (Nylon) and VeroWhite (photo-resin based rigid plastic) respectively. Our results indicate that the SC lattice structure outperforms in terms of stiffness and strength, while the Gyroid lattice outperforms in terms of energy absorption efficiency (η). At lower relative densities (<0.3), η reaches up to 61% for the Gyroid lattices made of PlasGray, while only at high relative densities the Octet truss lattices compete with the Gyroid lattices. For Gyroid lattices made of PA12 with a relative density of 0.23, an energy absorption efficiency of 68% was observed. Design maps are presented for all lattice structures processed and tested herein, to demonstrate their relative merits. Moreover, a two-step FEA was executed on a chosen array of lattices to thoroughly investigate the extensive design possibilities, utilising the elastic-plastic, Drucker-Prager, and concrete damage plasticity material models for PlasGray, PA12, and VeroWhite, respectively, with calibration based on experimental results. The results highlight that the tailored design of Gyroid lattices enabled by AM positions them as promising candidates for lightweight energy-absorbing applications.

Optical properties of tilted surfaces in material jetting

Material jetting (MJT) is a promising additive manufacturing (AM) technique that offers high-quality appearance reproduction. Considering the limited selection of aesthetic materials available for MJT technology, a thorough optical analysis is required to determine their optimal application. This study focuses on the prominent appearance attributes in MJT and the role of texture variation due to different build orientations (BOs). For this purpose, tilted surfaces were manufactured in a direction ranging from 0° to 90° degrees at 15° intervals. The spectral reflectance, absorbance, transmittance, color difference, gloss, haze, scattering, and texture of MJT objects with varying BOs were investigated. To illustrate the variation in visual appearance and texture of the studied surfaces, the optical properties were rendered to three-dimensional (3D) spherical models. Further, the interaction of the appearance of 3D printing interacts with the quality improvement of AM surfaces is discussed. The results indicated that BO significantly affected the surface texture and layer orientation, leading to variation in surface quality by impacting all studied appearance attributes. Furthermore, tilted MJT surfaces exhibited more variation in reflectance than transmittance. As a result of the Kendall rank correlation coefficient and principal component analysis (PCA), light transmittance through parts manufactured at BO 75° showed the largest variation compared to 0°. Regarding light reflectance, 60° showed more variation among studied angles. The results of gloss, haze, and scattering studies revealed the significance of the measurement direction due to the role of microsurface normals in the surface texture.

A Review on Progress, Challenges, and Prospects of Material Jetting of Copper and Tungsten.

Copper (Cu) and tungsten (W) possess exceptional electrical and thermal conductivity properties, making them suitable candidates for applications such as interconnects and thermal conductivity enhancements. Solution-based additive manufacturing (SBAM) offers unique advantages, including patterning capabilities, cost-effectiveness, and scalability among the various methods for manufacturing Cu and W-based films and structures. In particular, SBAM material jetting techniques, such as inkjet printing (IJP), direct ink writing (DIW), and aerosol jet printing (AJP), present a promising approach for design freedom, low material wastes, and versatility as either stand-alone printers or integrated with powder bed-based metal additive manufacturing (MAM). Thus, this review summarizes recent advancements in solution-processed Cu and W, focusing on IJP, DIW, and AJP techniques. The discussion encompasses general aspects, current status, challenges, and recent research highlights. Furthermore, this paper addresses integrating material jetting techniques with powder bed-based MAM to fabricate functional alloys and multi-material structures. Finally, the factors influencing large-scale fabrication and potential prospects in this area are explored.

Laser Polishing of Polymer Parts Produced with Material Jetting Technology: Effect of Laser Scan Speed, Overlapping and Loop Cycles

In the last year, the industrial production is characterized by the request of high level of product variety that generates a decrease of production volume changing manufacturing from mass production to mass customization. This trend let the conventional production processes, as forming, casting or moulding, expensive because of initial tools production cost that is not more amortized by the high-volume production. A solution to this scenario is to integrate Additive Manufacturing in tools production; this solution guarantees tools cost reduction also if post processes operations are needful to reduce the surface roughness produced by additive processes. Among additive processes, Material Jetting is able produce parts with guaranteed high accuracy and low average surface roughness (0.5 µm). However, these standards mainly refer to upfacing surfaces parallel to the print plate, and the roughness obtained on the other surfaces could increase up to 15 µm because of production mechanism. To improve parts roughness in this study, the laser polishing process was tested; different experimental tests were executed to investigate the effects of scan speed, overlapping and loop cycles. The results demonstrated that it is possible to improve the surface finish and reduce the roughness by 70% at the expense of dimensional accuracy.

Recent Advancements in 3-D Printing in Medical Applications

The field of three-dimensional (3D) printing has witnessed significant advancements in recent years, and its potential for revolutionizing medical applications is rapidly emerging. This review aims to provide an overview of the current state and scope of 3D printing in the medical field. The review begins by highlighting the various 3D printing technologies currently employed in healthcare settings, including stereolithography, selective laser sintering, fused deposition modeling, and inkjet printing. Each technology's advantages and limitations are discussed, shedding light on their suitability for different medical applications. Next, the review delves into the diverse range of medical applications where 3D printing has shown promise. These applications include the fabrication of patient-specific anatomical models for preoperative planning, surgical guides and tools, customized implants and prosthetics, tissue engineering scaffolds, and drug delivery systems. The potential benefits of using 3D printing in these areas, such as enhanced surgical accuracy, improved patient outcomes, reduced surgery time, and personalized medicine, are explored. Furthermore, the review addresses the challenges and limitations associated with implementing 3D printing in medical settings. These challenges include regulatory concerns, standardization of processes, material biocompatibility, cost-effectiveness, and scalability. The ongoing efforts to overcome these barriers and the future directions of 3D printing in medicine are also discussed. In conclusion, 3D printing holds immense potential for transforming various aspects of medical practice. While considerable progress has been made, there are still challenges to be addressed before widespread adoption can be achieved. With continued research and development, coupled with regulatory support and collaboration between academia, industry, and healthcare professionals, 3D printing is poised to International Journal of Scientific Research in Engineering and Management (IJSREM) Volume: 07 Issue: 07 | July - 2023 SJIF Rating: 8.176 ISSN: 2582-3930 © 2023, IJSREM | www.ijsrem.com DOI: 10.55041/IJSREM24845 | Page 2 make a substantial impact in the field of medicine, improving patient care and treatment outcomes. Key words: Additive manufacturing (AM); Bio-medical; Fused Deposition Modelling (FDM); Selective Laser Sintering (SLS); Stereolithography (SLA); Digital Light Processing (DLP); Binder Jetting; Material Jetting; Direct Energy Deposition (DED).

Process-structure-property effects of ultraviolet curing in multi-material jetting additive manufacturing

Material jetting (MJT) is an additive manufacturing process that involves selective jetting of a liquid material that is subsequently solidified, often via ultraviolet (UV) irradiation. The process presents designers with the opportunity to tune material properties on a voxel-by-voxel basis to fabricate high-resolution, multi-material parts. However, MJT is mainly constrained to prototyping and modeling applications, due to a limited selection of functional materials and challenges in attaining repeatable and reproducible part quality. Specifically, MJT’s indiscriminate UV dosing poses the risk of providing inconsistent dosing to parts, which could cause unintended variations in mechanical properties that are dependent on part design and build layout. To enable relating MJT processing conditions to final part properties, an MJT process model is presented that predicts accumulated exposure in parts of different materials, surface finishings, and build layouts by accounting for inputs relating to surface exposure, part design, and build plate configuration. Fundamentally guided by the Beer-Lambert law, the model leverages physical measurements of an MJT system, including UV spectral intensity distribution and toolpathing, to quantify cumulative exposure in batch-printed parts. Experimental characterization of parts printed in different configurations enabled correlation of parts’ total received exposure to their mechanical properties (tensile, three-point bend, Shore hardness, and dynamic mechanical analysis). It is observed that, especially in build layouts featuring multiple parts with dissimilar heights, the indiscriminate application of UV irradiation in MJT can lead to overexposure of parts, which results in changes in mechanical properties, including increased modulus and hardness. The effects of overexposure are largely dependent on material, toolpathing, and build layout. Connecting accumulated exposure to mechanical performance enables improved strategies for part design, build plate configuration, and process modification to better ensure consistency of UV dosage and reliable mechanical performance for batch-printed end-use parts.

Wearable triboelectric nanogenerator with micro-topping structures via material jet printing method

With the development of human-machine interactions, human healthcare monitoring and Internet of Things, it is of vital importance to explore revolutionary fabrication methods to provide sustainable and flexible energy harvesters for massive personnel information. In this work, we developed the micro-topping structures enhanced triboelectric nanogenerator (MT-TENG) via unique jet printing method with the advantages of high precision, high efficiency and excellent uniformity. Regular micro-topping structure array could be tuned conveniently and rapidly through adjusting the ink properties, printing parameters and substrate characteristics in jet printing process. The results show that with micro-topping structures, TENG has high specific surface for contact electrification. MT-TENG can be applied in the real-time monitoring and self-powered sensing of body physiological signal and human joint movement. This work provides a previously unexplored strategy for shortening individual design cycle and promoting the practicality of TENG in mass manufacturing, and also possess a potential application of wearable electronics and healthcare monitoring system.

Material jetting of carbon nano onions for printed electronics

As an additive manufacturing process, material jetting techniques allow to selectively deposit droplets of materials in liquid or powder form through a small-diameter aperture, such as a nozzle of a print head. For the fabrication of printed electronics, a variety of inks and dispersions of functional materials can be deposited by drop-on-demand printing on rigid and flexible substrates. In this work, zero-dimensional multi-layer shell-structured fullerene material, also known as carbon nano-onion (CNO) or onion-like carbon, is printed on polyethylene terephthalate substrates using drop-on-demand inkjet printing. CNOs are produced using a low-cost flame synthesis technique and characterized by electron microscopy, Raman, x-ray photoelectron spectroscopy, and specific surface area and pore size measurements. The produced CNO material has an average diameter of ∼33 nm, pore diameter in the range ∼2–40 nm and a specific surface area of 160 m2.g−1. The CNO dispersions in ethanol have a reduced viscosity (∼1.2 mPa.s) and are compatible with commercial piezoelectric inkjet heads. The jetting parameters are optimized to avoid satellite drops and to obtain a reduced drop volume (52 pL), resulting in optimal resolution (220 μm) and line continuity. A multi-step process is implemented without inter-layer curing and a fine control over the CNO layer thickness is achieved (∼180 nm thick layer after 10 printing passes). The printed CNO structures show an electrical resistivity of ∼600 Ω.m, a high negative temperature coefficient of resistance (−4.35 × 10−2 °C−1) and a marked dependency on relative humidity (−1.29 × 10−2 RH% −1). The high sensitivity to temperature and humidity, combined to the large specific area of the CNOs, make this material and the corresponding ink a viable prospect for inkjet-printed technologies, such as environmental and gas sensors.

Trueness of cone-beam computed tomography-derived skull models fabricated by different technology-based three-dimensional printers

BackgroundThree-dimensional (3D) printing is a novel innovation in the field of craniomaxillofacial surgery, however, a lack of evidence exists related to the comparison of the trueness of skull models fabricated using different technology-based printers belonging to different cost segments.MethodsA study was performed to investigate the trueness of cone-beam computed tomography-derived skull models fabricated using different technology based on low-, medium-, and high-cost 3D printers. Following the segmentation of a patient’s skull, the model was printed by: (i) a low-cost fused filament fabrication printer; (ii) a medium-cost stereolithography printer; and (iii) a high-cost material jetting printer. The fabricated models were later scanned by industrial computed tomography and superimposed onto the original reference virtual model by applying surface-based registration. A part comparison color-coded analysis was conducted for assessing the difference between the reference and scanned models. A one-way analysis of variance (ANOVA) with Bonferroni correction was applied for statistical analysis.ResultsThe model printed with the low-cost fused filament fabrication printer showed the highest mean absolute error (1.33pm 0.24 text{mm}), whereas both medium-cost stereolithography-based and the high-cost material jetting models had an overall similar dimensional error of 0.07pm 0.03 text{mm} and 0.07pm 0.01 text{mm}, respectively. Overall, the models printed with medium- and high-cost printers showed a significantly (p<0.01) lower error compared to the low-cost printer.ConclusionsBoth stereolithography and material jetting based printers, belonging to the medium- and high-cost market segment, were able to replicate the skeletal anatomy with optimal trueness, which might be suitable for patient-specific treatment planning tasks in craniomaxillofacial surgery. In contrast, the low-cost fused filament fabrication printer could serve as a cost-effective alternative for anatomical education, and/or patient communication.

Recent Advances in Additive Manufacturing, Applications and Challenges for Dentistry: A Review.

Technological advancement in the field of dentistry has to be proven in new avenues for professionals as well as laboratory programmers. An advanced type of technology is emerging based on digitalization, as a computerized three-dimensional (3-D) model, additive manufacturing also called 3-D printing, allows formation of block pieces by adding material layer-by-layer. The additive manufacturing (AM) approach has offered extreme progress in the broad choice of distinct zones, permitting the production of fragments of all possible varieties of substances such as metal, polymer, ceramic, and composites. The significant goal of current the article is to recapitulate the recent scenarios including the imminent perspective of AM techniques and challenges in dentistry. Moreover, this article reviews the recent developments of 3-D printing advancements along with the advantages and disadvantages. Herein, various AM technologies comprising vat photopolymerization (VPP), material jetting, material extrusion, selective laser sintering (SLS), selective laser melting (SLM), and direct metal laser sintering (DMLS) technologies based powder bed fusion technologies/direct energy deposition/sheet lamination centered on binder jetting technologies were discussed in detail. This paper attempts to provide a balanced view by emphasizing the economic, scientific, and technical challenges and presenting an overview of methods to discuss the similarities based on the authors' continuing research and development.

Evaluation of 3D Printed Burr Hole Simulation Models Using 8 Different Materials

3D printing is increasingly used to fabricate three-dimensional neurosurgical simulation models, making training more accessible and economical. 3D printing includes various technologies with different capabilities for reproducing human anatomy. This study evaluated different materials across a broad range of 3D printing technologies to identify the combination that most precisely represents the parietal region of the skull for burr hole simulation. Eight different materials (polyethylene terephthalate glycol, Tough PLA, FibreTuff, White Resin, BoneSTN, SkullSTN, polymide [PA12], glass-filled polyamide [PA12-GF]) across 4 different 3D printing processes (fused filament fabrication, stereolithography, material jetting, selective laser sintering) were produced as skull samples that fit into a larger head model derived from computed tomography imaging. Five neurosurgeons conducted burr holes on each sample while blinded to the details of manufacturing method and cost. Qualities of mechanical drilling, visual appearance, skull exterior, and skull interior (i.e., diploë) and overall opinion were documented, and a final ranking activity was performed along with a semistructured interview. The study found that 3D printed polyethylene terephthalate glycol (using fused filament fabrication) and White Resin (using stereolithography) were the best models to replicate the skull, surpassing advanced multimaterial samples from a Stratasys J750 Digital Anatomy Printer. The interior (e.g., infill) and exterior structures strongly influenced the overall ranking of samples. All neurosurgeons agreed that practical simulation with 3D printed models can play a vital role in neurosurgical training. The study findings reveal that widely accessible desktop 3D printers and materials can play a valuable role in neurosurgical training.

Material removal characteristics in submerged pulsating air jet polishing process

In this paper, the material removal characteristics and mechanism of submerged pulsating air jet polishing (SPAJP) process are investigated by polishing experiment on K9 glass and computational fluid dynamics simulation. The experimental results show SPAJP can etch almost perfect Gaussian footprints with high stability. Under comparable condition, SPAJP achieves nearly 300 times higher material removal rate (3.0 × 10−3 mm3/min) than that of traditional fluid jet polishing (FJP) (9.9 × 10−6 mm3/min) at the cost of a moderate degradation in processed surface roughness from Sa 3.97 nm by FJP to Sa 20.49 nm by SPAJP. Jet evolution, abrasive behavior and material removal mechanism in SPAJP are clarified by numerical modeling and experimental jet observation. It is found that SPAJP relies on jet instability of the submerged airflow beam to entrain and accelerate abrasive particles in the slurry, achieving stable and efficient polishing removal on the workpiece surface. To explore the potential of the process for deterministic polishing, an array structure surface is then designed and polished by SPAJP. The processing results are consistent with numerical prediction results, indicating that the new process has good material removal controllability which makes it applicable to deterministic polishing. This study highlights the possibility of using SPAJP to produce ultra-precise surfaces in terms of form control or fabricate high precision optical components in a more efficient and convenient manner.

Probabilistic fatigue life prediction for CSS-42L bearing in jet strengthen modification grinding using an improved WTP network

Considering the high quality requirement of advanced aeroengine equipment, accurate prediction of probabilistic fatigue life (PFL) for CSS-42 L bearing in jet strengthen modification grinding, is an important issue for aeroengine manufacturing. Here an improved robust prediction algorithm of Wavelet Transform Package (WTP) Network is designed, therefore the decisive influence of jet strengthen modification grinding on the probabilistic fatigue life of aeroengine bearing, could be predicted and analyzed. A complete set of comparative experiments demonstrate that, when Pw is 23.5 MPa, Mc is 225 g, Mb is 342 g, Ma is 304 g, Fa is 0.26 kg/min, and Ts is 40.7 mm/min, and Bf is 69.442%, Cs is 70.336%, Nb is 69.002%, Sb is 54.334%, Os is 67.334%, Fp is 71.254%, At is 33.557%, W is 56.375%, Tr is 62.445%, an optimal data set of FLC is 60.5 × 105, PFLS is 0.337, FLGV is 83.74 × 102, CMFD is 8.42, FDP is 79.43, and NPFD is 4.445 (error tolerance = ±5%), could be obtained. This research is novel and merited in implementing novel PFL prediction for CSS-42 L bearing, proposing PFL indexes to evaluate the fatigue performance of bearing material in jet strengthen modification grinding, and designing an improved WTP network to achieve accurate PFL prediction as well. Eventually it could be summarized that this research realizes extraordinary predictive capability and facilitates the productive PFL management for aeroengine equipment.

Experimental Investigation and Modeling of the Kerf Profile in Submerged Milling by Macro Abrasive Waterjet

Abstract Toward achieving control over the kerfing through macro abrasive waterjet submerged milling, there is a need (i) to understand the influence of the water column height on the kerf quality and (ii) to develop a model for the prediction of the kerf characteristics. This study performs detailed experimentation to assess the kerf quality enhancement in submerged milling relative to the in-air milling on Al-6061 alloy. From the modeling perspective, there are very limited efforts in developing a comprehensive model that includes both the jet flow dynamics and material removal models—this is the missing link. Toward this, a comprehensive model is proposed and validated for the prediction of kerf in in-air and submerged conditions by considering (i) jet dynamics and (ii) jet–material interaction. From the experimental results, it is observed that by adopting the submerged milling, the damaged region, top kerf width and edge radius got reduced by 20.3%, 13.53%, and 22.7%, respectively. However, this enhancement in the kerf quality is associated with a reduction in the centerline erosion depth (hmax) by 12.33% and a material removal rate by 24.52%. The material removal mechanism is more uniform and directed in the submerged milling, whereas in-air is random. The proposed model predicted the kerf cross-sectional profile in submerged milling and in-air with a mean absolute error of 60 µm and 57 µm, squared Pearson correlation coefficient of 0.97 and 0.99, and the hmax with a maximum error of 1.3% and 1.4%.

High-speed 3D printing for microfluidics: Opportunities and challenges

Traditional methods for the fabrication of microfluidic devices lead to the produced devices being expensive, involving time-consuming fabrication processes, and being limited in their design choices. In this review, we present the opportunities and challenges faced by 3D printing for microfluidic applications, with a key interest in the overall speed of the fabrication process. The development of high-speed methods for additive manufacturing (AM) of microfluidic devices is of interest to reduce the barrier of entry by further reducing the cost and fabrication time. This review investigates the key benefits of AM for microfluidic device fabrication, such as greater freedom of design and more complex devices to be created than is possible with traditional fabrication methods. Through complex three-dimensional microfluidic designs, it is possible to integrate features into a microfluidic device that traditionally would require external equipment, resulting in an even lower total cost of operating a microfluidic device leading to low-cost field-based applications. There are many methods for the AM of microfluidic devices: Stereolithography (SLA), Digital Light Processing (DLP), Material Jetting (MJ), and Fused Deposition Modelling (FDM). This review explores these various technologies and their suitability for the high-speed fabrication of microfluidic devices with this review showing that the preferred AM method selected for microfluidic device fabrication depends on desired use case of the microfluidic device.