Special Issue on “Machining Dynamics and Parameters Process Optimization”

In 1907, F.W Taylor—the father of production engineering—exposed the fundamentals of modern machining and defined chatter as the most obscure and delicate of all problems facing the machinist [...

Additively manufactured MEMS multiplexed coaxial electrospray sources for high-throughput, uniform generation of core–shell microparticles

his study reports the first MEMS multiplexed coaxial electrospray sources in the literature. Coaxial electrospraying is a microencapsulation technology based on electrohydrodynamic jetting of two immiscible liquids, which allows precise control with low size variation of the geometry of the core–shell particles it generates, which is of great importance in numerous biomedical and engineering applications, e.g., drug delivery and self-healing composites. By implementing monolithic planar arrays of miniaturized coaxial electrospray emitters that work uniformly in parallel, the throughput of the compound microdroplet source is greatly increased, making the microencapsulation technology compatible with low-cost commercial applications. Miniaturized core–shell particle generators with up to 25 coaxial electrospray emitters (25 emitters cm−2) were fabricated via stereolithography, which is an additive manufacturing process that can create complex microfluidic devices at a small fraction of the cost per device and fabrication time associated with silicon-based counterparts. The characterization of devices with the same emitter structure but different array sizes demonstrates uniform array operation. Moreover, the data demonstrate that the per-emitter current is approximately proportional to the square root of the flow rate of the driving liquid, and it is independent of the flow rate of the driven liquid, as predicted by the theory. The core/shell diameters and the size distribution of the generated compound microparticles can be modulated by controlling the flow rates fed to the emitters.Instituto Tecnologico y de Estudios Superiores de Monterre

Plataformas de vigilancia, extractivismo de marcas y prácticas de cuidado en la comunidad ballroom mexicana

The Mexican ballroom community made up of trans, transvestite and non-binary people uses sociodigital platforms to co-produce images-data and support their culture. However, its algorithmic visibility becomes surveillance and capitalist sieges that extract its data, practices, and symbolic resources to generate capital. This article analyzes both data on Instagram and interactions with brands to reveal the collaboration and care strategies that this community deploys. I use data mining software at a crossroads with digital ethnography for collection, visualization, and analysis.La comunidad ballroom mexicana integrada por personas trans, travestis y no binarixs emplea las plataformas sociodigitales para coproducir imágenes-datos y dar sostenimiento a su cultura. Sin embargo, su visibilidad algorítmica deviene en vigilancia y asedios capitalistas que extraen sus datos, prácticas y recursos simbólicos para generar capital. Este artículo analiza tanto datos en Instagram como interacciones con marcas para revelar las estrategias de colaboración y cuidados que dicha comunidad despliega. Utilizo software de minería de datos en un cruce con etnografía digital para la recolección, visualización y análisis

Improving Stability Prediction in Peripheral Milling of Al7075T6

Chatter is an old enemy to machinists but, even today, is far from being defeated. Current requirements around aerospace components call for stronger and thinner workpieces which are more prone to vibrations. This study presents the stability analysis for a single degree of freedom down-milling operation in a thin-walled workpiece. The stability charts were computed by means of the enhanced multistage homotopy perturbation (EMHP) method, which includes the helix angle but also, most importantly, the runout and cutting speed effects. Our experimental validation shows the importance of this kind of analysis through a comparison with a common analysis without them, especially when machining aluminum alloys. The proposed analysis demands more computation time, since it includes the calculation of cutting forces for each combination of axial depth of cut and spindle speed. This EMHP algorithm is compared with the semi-discretization, Chebyshev collocation, and full-discretization methods in terms of convergence and computation efficiency, and ultimately proves to be the most efficient method among the ones studied.The authors wish to acknowledge the financial support received from HAZITEK program, from the Department of Economic Development and Infrastructures of the Basque Government and from FEDER funds. Additional support was provided by the Tecnologico de Monterrey, through the Research Group in Nanomaterials and Devices Design

Prediction Methods and Experimental Techniques for Chatter Avoidance in Turning Systems: A Review

The general trend towards lightweight components and stronger but difficult to machine materials leads to a higher probability of vibrations in machining systems. Amongst them, chatter vibrations are an old enemy for machinists with the most dramatic cases resulting in machine-tool failure, accelerated tool wear and tool breakage or part rejection due to unacceptable surface finish. To avoid vibrations, process designers tend to command conservative parameters limiting productivity. Among the different machining processes, turning is responsible of a great amount of the chip volume removed worldwide. This paper reports some of the main efforts from the scientific literature to predict stability and to avoid chatter with special emphasis on turning systems. There are different techniques and approaches to reduce and to avoid chatter effects. The objective of the paper is to summarize the current state of research in this hot topic, particularly (1) the mechanistic, analytical, and numerical methods for stability prediction in turning; (2) the available techniques for chatter detection and control; (3) the main active and passive techniques.Thanks are addressed to Basque country university excellence group IT1337-19. The authors wish to acknowledge also the financial support received from HAZITEK program, from the Department of Economic Development and Infrastructures of the Basque Government and from FEDER funds. This research was funded by Tecnologico de Monterrey through the Research Group of Nanotechnology for Devices Design, and by the Consejo Nacional de Ciencia y Tecnologia (CONACYT), Project Numbers 242269, 255837, 296176, and the National Lab in Additive Manufacturing, 3D Digitizing and Computed Tomography (MADiT) LN299129

A model-based sustainable productivity concept for the best decision-making in rough milling operations

[EN]There is a need in manufacturing as in machining of being more productive. However, at the same time, workshops are also urged for lesser energy waste in cutting operations. Specially, rough milling of impellers and bladed integrated disks of aircraft engines need an efficient use of energy due to the long cycle times. Indeed, to avoid dramatic tool failures and idle times, cutting conditions and operations tend to be very conservative. This is a multivariable problem, where process engineers need to handle several aspects such as milling operation type, toolpath strategies, cutting conditions, or clamping systems. There is no criterion embracing productivity and power consumption. In this sense, this work proposes a methodology that meets productivity and sustainability by using a specific cutting energy or sustainable productivity gain (SPG) factor. Three rough milling operations-slot, plunge nad trochoidal milling-were modelled and verified. A bottom-up approach based on data from developed mechanistic force models evaluated and compared different alternatives for making a slot, which is a common operation in that king of workpieces. Experimental data confirmed that serrated end milling with the highest SPG value of 1 is the best milling operation in terms of power consumption and mass removal rate (MRR). In the case of plunge milling technique achieve an SPG < 0.51 while trochoidal milling produces a very low SPG value.The authors acknowledge the support from the Spanish Government (JANO, CIEN Project, 2019.0760) and Basque Government (ELKARTEK19/46, KK-2019/00004). This research was funded by Tecnologico de Monterrey through the Research Group of Nanotechnology for Devices Design, and by the Consejo Nacional de Ciencia y Tecnologia de Mexico (Conacyt), Project Number 296176, and National Lab in Additive Manufacturing, 3D Digitizing and Computed Tomography (MADiT) LN299129. The authors also acknowledge the support from Garikoitz Goikoetxea and fruitful discussions with Mr. Jon Mendez (Guhring (c)) and Endika Monge (Hoffmann Group (c))

Semi-Active Magnetorheological Damper Device for Chatter Mitigation during Milling of Thin-Floor Components

The productivity during the machining of thin-floor components is limited due to unstable vibrations, which lead to poor surface quality and part rejection at the last stage of the manufacturing process. In this article, a semi-active magnetorheological damper device is designed in order to suppress chatter conditions during the milling operations of thin-floor components. To validate the performance of the magnetorheological (MR) damper device, a 1 degree of freedom experimental setup was designed to mimic the machining of thin-floor components and then, the stability boundaries were computed using the Enhance Multistage Homotopy Perturbation Method (EMHPM) together with a novel cutting force model in which the bull-nose end mill is discretized in disks. It was found that the predicted EMHPM stability lobes of the cantilever beam closely follow experimental data. The end of the paper shows that the usage of the MR damper device modifies the stability boundaries with a productivity increase by a factor of at least 3.This research was funded by Tecnológico de Monterrey through the Research Group of Nanotechnology for Devices Design, and by the Consejo Nacional de Ciencia y Tecnología de México (Conacyt), Project Numbers 242269, 255837, 296176, and National Lab in Additive Manufacturing, 3D Digitizing and Computed Tomography (MADiT) LN299129

El ADN: biomolécula alternativa para la construcción de nanoestructuras y materiales compuestos

El ácido desoxirribonucleico, o ADN, es una biomolécula esencial para la transferencia de la información genética en los seres vivos que residen en el planeta. Las propiedades fisicoquímicas de este ácido nucleico tales como ionización de las bases heterocíclicas y la formación de puentes de hidrógeno entre bases complementarias, han atraído la atención de investigadores para la construcción de estructuras a nivel nanométrico. Una breve revisión de los trabajos reportados sobre este tema, así como la presentación de resultados recientes en la síntesis de nanoestructuras metálicas, mediante este biopolímero, son abordadas en este reporte. Desde la propuesta inicial de utilizar el ADN para producir nanoestructuras por uniones de sus cadenas, hace sólo unas décadas, hasta el diseño y desarrollo de nanomateriales basados en ADN, son presentados y discutidos, proponiendo al final una perspectiva de la tendencia de las líneas de investigación relacionadas.Deoxyribonucleic acid, or DNA, is an essential biomolecule for the genetic information transfer in living organisms, which reside in Earth. Physicochemical properties of this nucleic acid, such as heterocyclical bases ionization and hydrogen bonds interactions between complementary bases, have attracted the attention of researchers for construction of structures, at the nanometric level. A brief review on the reported works about this topic, as well as presentation of recent results in synthesis of metallic nanostructures by this polimer, are presented. From the initial proposal to employ DNA to produce nanostructures by the chains union, some decades ago, to the nanomaterials design and development based on DNA, are presented and discussed. Finally, the perspective to future trends for these research areas is mentioned

Infant Scale of Selective Attention: A Proposal to Assess Cognitive Abilities

The aim of this research was to test the Infant Scale of Selective Attention (EEAS, in Spanish) on healthy infants with no suspected neurological damage, in order to obtain normalcy initial parameters for the use of the instrument.The sample consisted of two hundred babies between two and eight months of age who were enrolled in the daycares of the Instituto Mexicano del Seguro Social. To obtain the normalcy initial parameters, descriptive statistics were used to calculate the mean, the standard deviation, the minimum and maximum scores, and percentiles. The EEAS allows for identification of delays in the development of the attention process by comparing an individual score to their age group in the tables. The findings of this study suggest that EEAS is a useful tool to evaluate the development of the attention process during infancy.El objetivo de la presente investigación fue probar la Escala de Evaluación de la Atención Selectiva (EEAS) en lactantes sanos sin sospecha de daño neurológico, con la finalidad de obtener parámetros iniciales de normalidad para el uso del instrumento. La muestra estuvo integrada por 200 lactantes con un rango de edad entre dos y ocho meses, adscritos al sistema de guarderías del Instituto Mexicano del Seguro Social. Para obtener los parámetros iniciales de normalidad se utilizó estadística descriptiva para calcular la media, la desviación estándar, puntajes máximos y mínimos y percentiles. La EEAS permite identificar retrasos en el desarrollo del proceso de atención al comparar un puntaje individual contra su grupo de edad en tablas. Los hallazgos de este estudio sugieren que la EEAS es un instrumento útil para evaluar el desarrollo del proceso de atención durante la infancia

Uncharted Stable Peninsula for Multivariable Milling Tools by High-Order Homotopy Perturbation Method

In this work, a new method for solving a delay differential equation (DDE) with multiple delays is presented by using second- and third-order polynomials to approximate the delayed terms using the enhanced homotopy perturbation method (EMHPM). To study the proposed method performance in terms of convergency and computational cost in comparison with the first-order EMHPM, semi-discretization and full-discretization methods, a delay differential equation that model the cutting milling operation process was used. To further assess the accuracy of the proposed method, a milling process with a multivariable cutter is examined in order to find the stability boundaries. Then, theoretical predictions are computed from the corresponding DDE finding uncharted stable zones at high axial depths of cut. Time-domain simulations based on continuous wavelet transform (CWT) scalograms, power spectral density (PSD) charts and Poincaré maps (PM) were employed to validate the stability lobes found by using the third-order EMHPM for the multivariable tool.This research was funded by Tecnológico de Monterrey through the Research Group of Nanotechnology for Devices Design, and by the Consejo Nacional de Ciencia y Tecnología de México (Conacyt), Project Numbers 242269, 255837, 296176, and National Lab in Additive Manufacturing, 3D Digitizing and Computed Tomography (MADiT) LN299129