Rapid Tooling Applications Research Articles

Effect of Printing Orientation Angle and Heat Treatment on the Mechanical Properties and Microstructure of Binder-Jetting-Printed Parts in 17-4 PH Stainless Steel

The present work aims to study the effect of printing orientation angle and heat treatment on the mechanical properties and microstructure of 17-4 PH stainless steel 3D-printed parts obtained by the binder jetting process to assess the suitability of the process and material for rapid tooling applications. To this purpose, tensile specimens were printed at different printing orientation angles (0°, 45°, and 90°). Half of the specimens were left in the as-sintered condition after the 3D-printing operation, while the other half of the specimens was subjected to H900 heat treatment. Then, tensile and hardness tests were performed to investigate the macro-mechanical properties as a function of the printing orientation angles and postprocessing thermal treatment. Scanning electron microscopy with energy dispersive X-ray spectroscopy was used to observe the fracture surfaces and microscopical defects on the binder jetting printed parts to evaluate the fracture mechanisms. It was demonstrated that printing orientation angles do not affect the mechanical properties of 3D-printed parts, while a significant improvement in the microstructure and mechanical properties is observed after the H900 heat treatment.

Smart design and additive manufacturing of bending tools to improve production flexibility

For the automotive industry, especially on the part of Tier 1 and Tier 2 suppliers, the future will be about maintaining sovereignty in the form of technology openness and accelerating digitization. The product portfolio, which is generally passed on by OEMs to suppliers for production, often includes body parts that cannot always be manufactured economically with the prevailing production technology. The reason for this is a high diversity of model-variants, which requires smaller batches. To this end, highly flexible large-series production cells for body sheet components that can be scaled in all dimensions are being developed and tested. For the first time, they will make it possible to redesign the process planning in series production on a component-specific basis. The aim is to reduce production costs for new, geometrically different component variants. The basic components of the flexible manufacturing system are, firstly, new flexible forming technologies which have the potential to produce typical vehicle part geometries. Secondly, a process generator develops the corresponding production plan. A digital mapping of the manufacturing processes enables the selection of cost-, efficiency-, flexibility- and resilience-optimized production chains depending on the number of parts. Established manufacturing processes to produce car body components are supplemented in the cell by flexible processes such as 3D swivel bending. As a use case for flexible manufacturing, a concept for Rapid Tooling of 3D swivel bending tools is developed. In the flexible manufacturing system to be developed, a method of a standardized process sequence to produce forming tools within 24 h has been lacking to date. For this purpose, the concept of an automated design is being developed in which a reconfigurable tool body can be sliced into sheet metal stripes The active tool surface is additively manufactured after the tool has been packaged using LMD and adapted to individual requirements. The goal in the application of Rapid Tooling is to reduce lead times and development costs through a largely automated tool design and lead time-optimized manufacturing concept.

On melt flow and wear properties of recycled Nylon 6-Zirconia composites for 3D printing in rapid tooling applications

Nylon 6 is one of the engineered thermoplastics which is known for its wear and chemical resistance properties. Also, the addition of hard oxide particles (e.g., Zirconium oxide (ZrO2)) into thermoplastics ensures the tuning of wear, mechanical and rheological properties. In this study, the melt flow and wear properties were investigated by varying the ZrO2 loading (up to 30% by weight) into the recycled nylon 6 polymer matrix. The melt flow rate of recycled Nylon 6-ZrO2 composite was measured as per the ASTM D1238 Standard. Further, wear rate & coefficient of friction (COF) were investigated. It has highlighted that the COF, melt flow index (MFI), and wear rate were greatly impacted by ZrO2 loading. It has been observed that the 70:30 ratio (by wt% of Nylon 6- ZrO2) has the lowest wear (200 µm) and COF (1.8). The results have confirmed that Nylon-30% ZrO2-based composite is a potential candidate for 3D printing in rapid tooling applications.

Producing Metal Powder from Machining Chips Using Ball Milling Process: A Review.

In the pursuit of achieving zero emissions, exploring the concept of recycling metal waste from industries and workshops (i.e., waste-free) is essential. This is because metal recycling not only helps conserve natural resources but also requires less energy as compared to the production of new products from virgin raw materials. The use of metal scrap in rapid tooling (RT) for injection molding is an interesting and viable approach. Recycling methods enable the recovery of valuable metal powders from various sources, such as electronic, industrial, and automobile scrap. Mechanical alloying is a potential opportunity for sustainable powder production as it has the capability to convert various starting materials with different initial sizes into powder particles through the ball milling process. Nevertheless, parameter factors, such as the type of ball milling, ball-to-powder ratio (BPR), rotation speed, grinding period, size and shape of the milling media, and process control agent (PCA), can influence the quality and characteristics of the metal powders produced. Despite potential drawbacks and environmental impacts, this process can still be a valuable method for recycling metals into powders. Further research is required to optimize the process. Furthermore, ball milling has been widely used in various industries, including recycling and metal mold production, to improve product properties in an environmentally friendly way. This review found that ball milling is the best tool for reducing the particle size of recycled metal chips and creating new metal powders to enhance mechanical properties and novelty for mold additive manufacturing (MAM) applications. Therefore, it is necessary to conduct further research on various parameters associated with ball milling to optimize the process of converting recycled copper chips into powder. This research will assist in attaining the highest level of efficiency and effectiveness in particle size reduction and powder quality. Lastly, this review also presents potential avenues for future research by exploring the application of RT in the ball milling technique.

Potential of New Sustainable Green Geopolymer Metal Composite (GGMC) Material as Mould Insert for Rapid Tooling (RT) in Injection Moulding Process.

The investigation of mould inserts in the injection moulding process using metal epoxy composite (MEC) with pure metal filler particles is gaining popularity among researchers. Therefore, to attain zero emissions, the idea of recycling metal waste from industries and workshops must be investigated (waste free) because metal recycling conserves natural resources while requiring less energy to manufacture new products than virgin raw materials would. The utilisation of metal scrap for rapid tooling (RT) in the injection moulding industry is a fascinating and potentially viable approach. On the other hand, epoxy that can endure high temperatures (>220 °C) is challenging to find and expensive. Meanwhile, industrial scrap from coal-fired power plants can be a precursor to creating geopolymer materials with desired physical and mechanical qualities for RT applications. One intriguing attribute of geopolymer is its ability to endure temperatures up to 1000 °C. Nonetheless, geopolymer has a higher compressive strength of 60-80 MPa (8700-11,600 psi) than epoxy (68.95 MPa) (10,000 psi). Aside from its low cost, geopolymer offers superior resilience to harsh environments and high compressive and flexural strength. This research aims to investigate the possibility of generating a new sustainable material by integrating several types of metals in green geopolymer metal composite (GGMC) mould inserts for RT in the injection moulding process. It is necessary to examine and investigate the optimal formulation of GGMC as mould inserts for RT in the injection moulding process. With less expensive and more ecologically friendly components, the GGMC is expected to be a superior choice as a mould insert for RT. This research substantially impacts environmental preservation, cost reduction, and maintaining and sustaining the metal waste management system. As a result of the lower cost of recycled metals, sectors such as mould-making and machining will profit the most.

SLA Resins Modification by Liquid Mixing with Ceramic Powders Aiming at Mechanical Property and Thermal Stability Enhancement for Rapid Tooling Applications

Stereolithography (SL) additive manufacturing process provides increased dimensional precision, smooth surface finish and printing resolution range in the order of magnitude of 100 μm, allowing to obtain intricate 3D geometries. The incorporation of ceramic-based inclusions within liquid resins enhances the thermal and mechanical properties of the final 3D printed component while improving the surface finishing of the final parts; in this way, it expands the range of process applications and reduces the post-processing steps. The proposed approach investigates the bulk modification of commercial SLA resins mixed with ceramic powders of Al2O3 (grain size 1–10 μm) and SiO2 (grain size 55–75 nm) aiming to improve 3D printed parts performance in terms of mechanical properties, dimensional stability and surface finishing compared with pure, unmodified resins. The produced materials were used for the development of inserts for injection moulding and were examined for their performance during the injection moulding process. The addition of particles in the nano- and micro-range is being employed to improve parts performance for rapid tooling applications whilst maintaining 3D printing accuracy, thermal and mechanical properties as well as achieving a smooth surface finishing compared with unmodified resins.

Micro injection moulding process with high-temperature resistance resin insert produced with material jetting technology: Effect of part orientation

Material jetting is an additive manufacturing technology used to produce resin parts with high accuracy and good surface finish. It is often used for visual prototypes or for rapid tooling applications to realise moulds for the standard injection moulding process because of the mechanical properties of the material. However, owing to the poor thermal properties of the resin, this technology is limited by the melting temperature of the material and the production rate. Currently, newer resins are able to withstand temperatures up to 250 °C. To enhance the potential of this technology, in this study the authors tested the performance of a mould insert for microinjection moulding application, produced with a high-temperature resin. In particular, it has been analysed how the orientation of the mould insert on the build plate significantly affects the insert resistance and surface roughness and consequently the quality of the moulded part. The results obtained open up new possibilities for testing a series of small batches and highlight new challenges to improve the process performance.

Evaluating interlayer gaps in friction stir spot welds for rapid tooling applications

Potential for a rapid hybrid additive/subtractive manufacturing technique capable of generating large aluminum components with deep geometrical features exists if, for example, layers of aluminum plates can be deposited and held in place using friction stir welding followed by machining. However, when plates of aluminum are friction stir spot welded together, adjacent material can deform causing a gap between layers. This research investigates how friction stir tool geometry affects the formation of interlayer gaps and the lap shear strength of the weld. For this purpose, residual stresses and microhardness were measured to characterize the weld formation process. While friction stir welding of 6061 aluminum bar stock was carried out on a machining center with three different pin diameters (5.7, 6.4, 7.0 mm) and two pin lengths (8.9, 10.2 mm). In general, outcomes of the research show that lap shear strength trends upward with increasing pin diameter but does not show a strong relation to the pin length. Interlayer gap size increases with pin length, but does not show a clear trend with pin diameter. Compressive residual stresses were observed on the weld shoulder with no significant variations occurring among the studied stir tool geometries. No significant change was measured in microhardness values when the pin length or shoulder diameter were changed, suggesting that the increase in lap shear strength is due to a change in weld cross-section instead of a material property change. This research will guide friction stir tool geometry selection for this hybrid manufacturing process and can be applied more broadly to any application where material deformation around a weld is undesirable.

On 3D printing of PA6-10% almond skin powder reinforced composite

In past one decade, polyamide (PA)6 feedstock filaments has proved its capabilities for fused deposition modeling (FDM) based functional prototypes requiring wear and impact resistance. The almond skin powder (ASP) is organic kitchen waste material, which has highest strength to weight ratio. Some researchers have developed PA6 based composite feedstock filament reinforced with ASP. But hitherto little has been reported on use of ASP reinforced PA6 based composite filament for 3D printing (using FDM) and its printing capabilities. In this research work an effort has been made to 3D print, 10% (by weight) ASP reinforced PA6 composite filament with open source FDM setup as a pilot study. The results are supported with mechanical testing, optical photo-micro graphical analysis. The functional prototype can be very useful in meta-material printing (requiring high modulus of toughness) and rapid tooling applications.

Characteristics of rifampicin-resistant tuberculosis detection in China, 2015\u20132019

BackgroundThe very high burden of rifampicin resistance tuberculosis (RR-TB) and the very low detection of RR-TB cases are a major challenge that China has been facing. This study analyzed the characteristics of RR-TB detection in China after the change of RR-TB detection strategy since 2015, aiming to provide reference and evidence for the development of more precise national drug resistance tuberculosis prevention and control policy.MethodsWe extracted data related to rifampicin resistance screening from the national Tuberculosis Information Management System (TBIMS) from 2015 to 2019, and used descriptive research methods to analyze the screening rate of presumptive RR-TB, the number and duration of RR-TB patients detected and drug resistance testing methods in each year. Chi-square test was used to compare the differences in component ratio or rate between years, and Kruskal Wallis test was used to compare the differences in median days for detection of RR-TB patients in each year.ResultsA total of 68,200 RR-TB cases were detected during 2015–2019, of which 48.1% were new cases. The number and detection rate of RR-TB cases increased year by year, from 10 019 and 14.3% in 2015 to 18 623 and 28.7% in 2019, respectively. Of the bacteriologically confirmed TB cases, 81.9% were tested for RR in 2019, a considerable increase from 29.5% in 2015. In 2019, only 41.0% of RR-TB cases had fluoroquinolones (FQs) susceptibility testing performed, and this proportion has been declining year by year since 2016. The proportion of application of rapid molecular tools increased from 24.0% in 2015 to 67.1% in 2019, and the median days to obtain RR results was significantly shortened. In 2019, 76.0% of RR-TB cases were diagnosed as presumptive RR-TB in county-level hospitals.ConclusionsAfter China modified the RR-TB detection strategy, the screening rate of RR and the number of RR-TB cases increased significantly. The RR testing methods now predominantly utilize rapid molecular tools. However, comprehensive measures should be implemented to close the gap in the detection of RR-TB cases. It is imperative to take FQs susceptibility testing seriously and effectively strengthen the laboratory capacity of county-level hospitals.Graphical

The potential of metal epoxy composite (MEC) as hybrid mold inserts in rapid tooling application: a review

Purpose Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts. Design/methodology/approach The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted. Findings Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles). Research limitations/implications The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available. Originality/value This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.

Sustainability metrics for rapid manufacturing of the sand casting moulds: A multi-criteria decision-making algorithm-based approach

Additive Manufacturing has significantly developed over the years and is widely used in most industrial applications. Rapid Tooling refers to manufacturing the tools (moulds and dies) using Additive Manufacturing techniques. An essential application of Rapid Tooling is the 3D printing of sand moulds for castings. Metal casting is an energy-intensive process; and a lot of research has gone into the sustainability assessment of traditional sand castings. In this work, a robust decision-making approach is developed and implemented for sand mould manufacturing. Sustainability metrics for the mould production are formulated, and the conventional sand moulds are compared against the 3D printed sand moulds. A Multi-Criteria decision-making algorithm is implemented, and the effect of the batch size in the mould manufacturing is also studied. The discussed approach can help decision-makers choose the best mould manufacturing technique for the intended number of moulds to be manufactured.

A review on 3D printed polymer-based composite for thermal applications

Recently, 3D printing techniques for the polymer-based part has become popular in the industry and academic area. Fused deposition modelling (FDM) is one of the most popular methods among 3D printing techniques because of its low cost, ability to fabricate objects with complex structures and geometries, specific functions, ease in processing, safety, reliability, and availability of various thermoplastic materials. This technique’s application is widespread on the electronic application, medical application, and rapid tooling applications. This paper aims to review fused deposition modelling (FDM) 3D printed polymer-based composite techniques for thermal management applications. This paper will provide an overview of fused deposition modelling (FDM) techniques in 3D printing, conducting polymer base and conducting nanofiller additive material used, and current trend research in this area.

Epidemiological Characteristics of Rifampicin-Resistant Tuberculosis in Students - China, 2015-2019.

What is already known about this topic? The number of students with tuberculosis (TB) has been increasing since 2015. However, the prevalence of rifampicin-resistant tuberculosis (RR-TB) among student population is unclear. What is added by the report? The number of students with RR-TB has significantly increased from 2015 to 2019, especially in the western region of China. The majority of patients were college students. Students with RR-TB were mainly new patients. What are the implications for public health practice? The following measures are recommended: strengthening TB surveillance in schools, promoting the application of convenient and rapid molecular drug susceptibility testing tools, and actively carrying out drug resistance screening and follow ups for cohabiting children of adult RR-TB patients.

Selective laser melting and tempering of H13 tool steel for rapid tooling applications

H13 components with a relative density of ∼99% were additively manufactured using the selective laser melting (SLM) process. The highest density part (relevant density 99%) with the lowest level of porosity (<0.01%) was made with a volumetric energy density of 760 J/mm3 (152 W laser power, 100 mm/s scanning speed, 40 μm hatch spacing, and 50 μm layer thickness). Wrought and additively manufactured samples underwent tempering at 550, 600, and 650 °C for 2 h followed by furnace cooling. Additively manufactured samples and wrought H13 samples that were austenitized followed by water quenching were martensitic with similar microhardness values of 708.4 ± 25.0 HV and 708.1 ± 12.6 HV, respectively. A tempered martensitic structure was observed in SLM-manufactured and tempered samples. Samples that were additively manufactured and tempered at 550 °C showed higher microhardness (728.5 ± 28.2 HV) than non-tempered SLM-manufactured samples due to an upward shift in the secondary hardening phase. Tempering at 600 and 650 °C resulted in coarsening of the carbides and martensite, which led to a reduction in microhardness. Additively manufactured samples maintained higher microhardness values than wrought H13 samples at all tempering temperatures, likely because of higher dislocation density, finer grains present, and higher volume fraction of carbide nanoparticles.

Featuring COVID-19 cases via screening symptomatic patients with epidemiologic link during flu season in a medical center of central Taiwan.

BackgroundCoronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CO-V-2), was first reported in Wuhan, Hubei province, China has now rapidly spread over 50 countries. For the prevention and control of infection, Taiwan Centers for Disease Control initiated testing of SARS-CoV-2 on January 24th 2020 for persons suspected with this disease. Until February 28th, 43 flu-like symptomatic patients were screened in China Medical University Hospital.MethodsTwo patients were confirmed positive for SARS-CoV-2 infection by rRT-PCR as COVID-19 patients A and B. Causative pathogens for included patients were detected using FilmArray™ Respiratory Panel. We retrospectively analyzed the clinical presentations, laboratory data, radiologic findings, and travel and exposure contact histories, of the COVID-19 patients in comparison to those with other respiratory infections.ResultsThrough contact with Taiwan No. 19 case patient on 27th January, COVID-19 patients A and B were infected. Both patients had no identified comorbidities and developed mild illness with temporal fever, persistent cough, and lung interstitial infiltrates. Owing to the persistence of positive SARS-CoV-2 in respiratory specimen, the two COVID-19 patients are still in the isolation rooms despite recovery until 10th of March. The results of FilmArrayTM Respiratory Panel revealed 22 of the 41 non-COVID-19 patients were infected by particular pathogens. In general, seasonal respiratory pathogens are more prevalent than SARS-CoV-2 in symptomatic patients in non- COVID-19 endemic area during the flu season. Since all patients shared similar clinical and laboratory findings, expanded surveillance of detailed exposure history for suspected patients and application of rapid detection tools are highly recommended.

Three-dimensional-printed molds and materials for injection molding and rapid tooling applications

Abstract

On the Optimal Design of Metal Matrix Composites as Functionally Graded Innovative Materials for Sensor Devices

In the present work an effort has been made to prepare Al matrix composite by 3D printing assisted rapid investment casting (RIC). The RIC has been performed by using patterns prepared by fused deposition modelling (FDM). For preparation of 3D parts, a composite material reinforced with ceramic particles (SiC and Al2O3) has been used as filament wire. The main motive of this research work is to prepare metal matrix composites as functionally graded innovative materials (FGIM), via investment casting as functional prototypes which will have wear resistance properties of SiC and Al2O3 (especially in rapid tooling (RT) applications. The reinforcements in the RT (as functional prototype) have been ensured by SEM analysis. The potential of the analysed materials for the fabrication of novel sensor devices is highlighted. Also the functional prototypes were checked for process capability analysis for batch production

New Subgenotyping and Consensus Real-Time Reverse Transcription-PCR Assays for Hepatitis A Outbreak Surveillance

Laboratory surveillance plays an important role in the detection and control of hepatitis A outbreaks and requires the application of rapid and accurate molecular diagnostic tools for hepatitis A virus (HAV) RNA detection, subgenotype identification, and sequence-based genotyping. We describe the development and validation of a triplex real-time, reverse transcription-PCR (triplex rRT-PCR) assay for the identification and discrimination of HAV subgenotypes IA, IB, and IIIA and a singleplex rRT-PCR assay designed to detect all HAV genotypes infecting humans. Overall, the accuracy, sensitivity, and specificity of the new assays were >97% for serum and plasma specimens collected during unrelated outbreaks of HAV in California and Michigan compared to a nested RT-PCR genotyping assay and the ISO 15216-1 rRT-PCR method for HAV detection. The new assays will permit the rapid detection of HAV RNA and discrimination among subgenotypes IA, IB, and IIIA in serum and plasma specimens, which will strengthen public health surveillance efforts for HAV outbreak detection and response.

Thermal analysis based method development for novel rapid tooling applications

The use of soft molds manufactured by additive manufacturing is gaining popularity in small-series production, thanks to the development of additive technologies and their materials. The thermal properties of soft molds, however, differ considerably from those of conventional, metal molds, and this greatly affects the conditions in the mold during manufacturing. We investigated the thermal properties and cooling conditions of epoxy acrylate-based, directly manufactured soft prototype molds. We used four different mold inserts, two with conformal cooling, one with conventional cooling and one without cooling. We found that due to the poor thermal properties of the mold material, the thermal conditions in the insert with conventional cooling and the insert without cooling were almost identical, this proves that in this case, conventional cooling cannot remove heat effectively. The use of conformal cooling, however, can reduce the cyclic heat load of mold inserts by about 70%, which increases the lifetime of the mold.