Efficient toolpath planning for collaborative material extrusion machines

Purpose: Timing constraints affect the manufacturing of traditional large-scale components through the material extrusion technique. Thus, researchers are exploring using many independent and collaborative heads that may work on the same part simultaneously while still producing an appealing final product. The purpose of this paper is to propose a simple and repeatable approach for toolpath planning for gantry-based n independent extrusion heads with effective collision avoidance management. Design/methodology/approach: This research presents an original toolpath planner based on existing slicing software and the traditional structure of G-code files. While the computationally demanding component subdivision task is assigned to computer-aided design and slicing software to build a standard G-code, the proposed algorithm scans the conventional toolpath data file, quickly isolates the instructions of a single extruder and inserts brief pauses between the instructions if the non-priority extruder conflicts with the priority one. Findings: The methodology is validated on two real-life industrial large-scale components using architectures with two and four extruders. The case studies demonstrate the method's effectiveness, reducing printing time considerably without affecting the part quality. A static priority strategy is implemented, where one extruder gets priority over the other using a cascade process. The results of this paper demonstrate that different priority strategies reflect on the printing efficiency by a factor equal to the number of extrusion heads. Originality/value: To the best of the authors’ knowledge, this is the first study to produce an original methodology to efficiently plan the extrusion heads' trajectories for a collaborative material extrusion architecture

A design of experiment approach to 3D-printed mouthpieces sound analysis

Nowadays additive manufacturing is affected by a rapid expansion of possible applications. It is defined as a set of technologies that allow the production of components from 3D digital models in a short time by adding material layer by layer. It shows enormous potential to support wind musical instruments manufacturing because the design of complex shapes could produce unexplored and unconventional sounds, together with external customization capabilities. The change in the production process, material and shape could affect the resulting sound. This work aims to compare the music performances of 3D-printed trombone mouthpieces using both Fused Deposition Modelling and Stereolithography techniques, compared to the commercial brass one. The quantitative comparison is made applying a Design of Experiment methodology, to detect the main additive manufacturing parameters that affect the sound quality. Digital audio processing techniques, such as spectral analysis, cross-correlation and psychoacoustic analysis in terms of loudness, roughness and fluctuation strength have been applied to evaluate sounds. The methodology herein applied could be used as a standard for future studies on additively manufactured musical instruments

Optimization with artificial intelligence in additive manufacturing: a systematic review

In situations requiring high levels of customization and limited production volumes, additive manufacturing (AM) is a frequently utilized technique with several benefits. To properly configure all the parameters required to produce final goods of the utmost quality, AM calls for qualified designers and experienced operators. This research demonstrates how, in this scenario, artificial intelligence (AI) could significantly enable designers and operators to enhance additive manufacturing. Thus, 48 papers have been selected from the comprehensive collection of research using a systematic literature review to assess the possibilities that AI may bring to AM. This review aims to better understand the current state of AI methodologies that can be applied to optimize AM technologies and the potential future developments and applications of AI algorithms in AM. Through a detailed discussion, it emerges that AI might increase the efficiency of the procedures associated with AM, from simulation optimization to in-process monitoring

Conformal 3D Material Extrusion Additive Manufacturing for Large Moulds

Industrial engineering applications often require manufacturing large components in composite materials to obtain light structures; however, moulds are expensive, especially when manufacturing a limited batch of parts. On the one hand, when traditional approaches are carried out, moulds are milled from large slabs or laminated with composite materials on a model of the part to produce. In this case, the realisation of a mould leads to adding time-consuming operations to the manufacturing process. On the other hand, if a fully additively manufactured approach is chosen, the manufacturing time increases exponentially and does not match the market’s requirements. This research proposes a methodology to improve the production efficiency of large moulds using a hybrid technology by combining additive manufacturing and milling tools. A block of soft material such as foam is milled, and then the printing head of an additive manufacturing machine deposits several layers of plastic material or modelling clay using conformal three-dimensional paths. Finally, the mill can polish the surface, thus obtaining a mould of large dimensions quickly, with reduced cost and without needing trained personnel and handcraft polishing. A software tool has been developed to modify the G-code read by an additive manufacturing machine to obtain material deposition over the soft mould. The authors forced conventional machining instructions to match those of an AM machine. Thus, additive deposition of new material uses 3D conformal trajectories typical of CNC machines. Consequently, communication between two very different instruments using the same language is possible. At first, the code was tested on a modified Fused Filament Fabrication machine whose firmware has been adapted to manage a milling tool and a printing head. Then, the software was tested on a large machine suitable for producing moulds for the large parts typical of marine and aerospace engineering. The research demonstrates that AM technologies can integrate conventional machinery to support the composite materials industry when large parts are required

Maintenance in aeronautics in an Industry 4.0 context: The role of Augmented Reality and Additive Manufacturing

The paper broadly addresses how Industry 4.0 program drivers will impact maintenance in aviation. Specifically, Industry 4.0 practices most suitable to aeronautical maintenance are selected, and a detailed exposure is provided. Advantages and open issues are widely discussed and case studies dealing with realistic scenarios are illustrated to support what has been proposed by authors. The attention has been oriented towards Augmented Reality and Additive Manufacturing technologies, which can support maintenance tasks and spare parts production, respectively. The intention is to demonstrate that Augmented Reality and Additive Manufacturing are viable tools in aviation maintenance, and while a strong effort is necessary to develop an appropriate regulatory framework, mandatory before the wide-spread introduction of these technologies in the aerospace systems maintenance process, there has been a great interest and pull from the industry sector

Intrinsic Dimension Estimation: Relevant Techniques and a Benchmark Framework

When dealing with datasets comprising high-dimensional points, it is usually advantageous to discover some data structure. A fundamental information needed to this aim is the minimum number of parameters required to describe the data while minimizing the information loss. This number, usually called intrinsic dimension, can be interpreted as the dimension of the manifold from which the input data are supposed to be drawn. Due to its usefulness in many theoretical and practical problems, in the last decades the concept of intrinsic dimension has gained considerable attention in the scientific community, motivating the large number of intrinsic dimensionality estimators proposed in the literature. However, the problem is still open since most techniques cannot efficiently deal with datasets drawn from manifolds of high intrinsic dimension and nonlinearly embedded in higher dimensional spaces. This paper surveys some of the most interesting, widespread used, and advanced state-of-the-art methodologies. Unfortunately, since no benchmark database exists in this research field, an objective comparison among different techniques is not possible. Consequently, we suggest a benchmark framework and apply it to comparatively evaluate relevant state-of-the-art estimators

226 Comparison between standard and empiric Spirotiger® setup in patients with cystic fibrosis (CF)

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The 4 K outer cryostat for the CUORE experiment: construction and quality control

The external shell of the CUORE cryostat is a large cryogen-free system designed to host the dilution refrigerator and the bolometers of the CUORE experiment in a low radioactivity environment. The three vessels that form the outer shell were produced and delivered to the Gran Sasso underground Laboratories in July 2012. In this paper, we describe the production techniques and the validation tests done at the production site in 2012.Comment: 11 pages, 13 figures; to appear in NIM

Haemorrhagic enteritis seroconversion in turkey breeders: field observations

Seroconversion to viral haemorrhagic enteritis (HE) was studied in seven flocks of turkey breeders (17.974 birds in total), after 20 weeks of the onset of egg production. They showed no clinical signs, and mortality rate was normal. However, the infection caused a drop in egg production lasting about five weeks (-2.32 eggs laid during this period), but had no effect on hatching parameters

Spatial distribution of stored grain insects in a rice storage and processing facility in Brazil

This study describes the spatial distribution of stored product insects captured biweekly using foodbaited cage traps in a large rice storage and processing facility, in the state of Rio Grande do Sul, Brazil. Monitoring started in August 2009 and will be carried out for 1 year, the first 5 months of sampling being presented in this study. From end of August 2009 until the end of December 2009, a total of 9893 insects were captured in the 99 cage traps. The most abundant species were: Carpophilus spp. (76%), Typhaea stercorea (8.6%), Ahasverus advena (5.5%), Tribolium castaneum (2.3%), Sitophilus oryzae (2%), Sitophilus zeamais (1.5%), Ephestia spp. (1.2 %), Cryptolestes ferrugineus (1%), Rhyzopertha dominica (0.64%), Oryzaephilus surinamensis (0.6%), Anthicus floralis (0.4%), Lasioderma serricorne (0.25%). The first two species, which make up for 84.6% of the insects collected, are not considered pests in stored grain, rather are attracted by moldy material present in residues or even in the bait material. The other insects, including primary and secondary species, comprised about 15% of the total trapped. The spatial distribution of the most important species infesting rice grain and of the total insect number was analyzed using Surfer 6.04 (Golden software, Golden, CO, USA) and contour maps were constructed to target areas for sanitation. Except for trap 66, located by the rice hulk storage box, the spatial distribution we observed using the contour maps showed that the greatest number of insects was mostly captured in cages placed in the receiving area, around the dryers, as well as outside of the structure where grain residues frequently accumulate. As indicated on the maps for total number of insects, a few isolated infested spots were detected. The parboiled rice area had the least amount of insects, except for trap 61, placed outside the structure. The population of primary and the most important secondary insect species, as well as the overall number of insects, decreased after sanitation and physical control measures were applied. Our observations confirm that insect monitoring is an essential tool for targeting and evaluating the control measures adopted in the quality program of rice storage and processing facilities. Keywords: Insect monitoring; Spatial distribution; Stored grain pests; Stored ric