Advances in Micro and Nano Manufacturing: Process Modeling and Applications

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "D:Materials and Processing".

Deadline for manuscript submissions: closed (30 November 2020) | Viewed by 37081

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Guest Editor
Department of Industrial Engineering, University of Padova, Via Venezia 1, 35131 Padova, Italy
Interests: polymer processing; injection molding; fiber-reinforced plastic; polymers
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Special Issue Information

Dear Colleagues,

Micro and nano manufacturing technologies have been developed in research and industrial environment with the goal of supporting product miniaturization and integration of new functionalities. The technological development of new materials and processing methods needs to be supported by predictive models, which can simulate the interactions between materials, process states, and product properties. In comparison with the conventional manufacturing scale, micro and nano scale technologies require the study of different mechanical, thermal, and fluid dynamics, phenomena that need to be studied and modeled.

This Special Issue is dedicated to advances in the modeling of micro and nano manufacturing processes (micro/nano injection molding, powder injection molding, micro milling, micro EDM, micro water-jet, additive manufacturing, etc.). Invited and submitted articles should investigate the development of new models, validation of state-of-the-art modeling strategies, and approaches to material model calibration. Authors are encouraged to compare theoretical predictions to experimental observations, and examine the effect of different processing factors on selected process response variables. This Special Issue is not limited with respect to the type of material and manufacturing method. The goal is to provide state-of-the-art examples of the use of modeling and simulation in micro and nano manufacturing processes, promoting the diffusion and development of these technologies.
We look forward to receiving your contributions!

Prof. Davide Masato
Prof. Giovanni Lucchetta
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Micro manufacturing
  • Modeling
  • Simulation
  • Materials
  • Processing

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Published Papers (13 papers)

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Editorial

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3 pages, 160 KiB  
Editorial
Editorial for the Special Issue on Advances in Micro and Nano Manufacturing: Process Modeling and Applications
by Davide Masato and Giovanni Lucchetta
Micromachines 2021, 12(8), 970; https://doi.org/10.3390/mi12080970 - 16 Aug 2021
Cited by 1 | Viewed by 1346
Abstract
Micro- and nano-manufacturing technologies have been developed in research and industrial environments to support product miniaturization and the integration of new functionalities [...] Full article

Research

Jump to: Editorial, Other

18 pages, 5126 KiB  
Article
The Micro Topology and Statistical Analysis of the Forces of Walking and Failure of an ITAP in a Femur
by Euan Langford, Christian Andrew Griffiths, Andrew Rees and Josh Bird
Micromachines 2021, 12(3), 298; https://doi.org/10.3390/mi12030298 - 12 Mar 2021
Cited by 2 | Viewed by 1930
Abstract
This paper studies the forces acting upon the Intraosseous Transcutaneous Amputation Prosthesis, ITAP, that has been designed for use in a quarter amputated femur. To design in a failure feature, utilising a safety notch, which would stop excessive stress, σ, permeating the bone [...] Read more.
This paper studies the forces acting upon the Intraosseous Transcutaneous Amputation Prosthesis, ITAP, that has been designed for use in a quarter amputated femur. To design in a failure feature, utilising a safety notch, which would stop excessive stress, σ, permeating the bone causing damage to the user. To achieve this, the topology of the ITAP was studied using MATLAB and ANSYS models with a wide range of component volumes. The topology analysis identified critical materials and local maximum stresses when modelling the applied loads. This together with additive layer manufacture allows for bespoke prosthetics that can improve patient outcomes. Further research is needed to design a fully functional, failure feature that is operational when extreme loads are applied from any direction. Physical testing is needed for validation of this study. Further research is also recommended on the design so that the σ within the ITAP is less than the yield stress, σs, of bone when other loads are applied from running and other activities. Full article
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15 pages, 32578 KiB  
Article
Experimental Investigation on Laser Assisted Diamond Turning of Binderless Tungsten Carbide by In-Process Heating
by Kaiyuan You, Fengzhou Fang, Guangpeng Yan and Yue Zhang
Micromachines 2020, 11(12), 1104; https://doi.org/10.3390/mi11121104 - 14 Dec 2020
Cited by 29 | Viewed by 3106
Abstract
Binderless tungsten carbide (WC) finds widespread applications in precision glass molding (PGM). Grinding and polishing are the main processes to realize optical surface finish on binderless WC mold inserts. The laser assisted turning (LAT) by in-process heating is an efficient method to enhance [...] Read more.
Binderless tungsten carbide (WC) finds widespread applications in precision glass molding (PGM). Grinding and polishing are the main processes to realize optical surface finish on binderless WC mold inserts. The laser assisted turning (LAT) by in-process heating is an efficient method to enhance the machinability of hard and brittle materials. In this paper, laser heating temperature was pre-calculated by the finite element analysis, and was utilized to facilitate laser power selection. The effects of rake angle, depth of cut, feed rate, and laser power are studied experimentally using the Taguchi method. The variance, range, and signal-to-noise ratio analysis methods are employed to evaluate the effects of the factors on the surface roughness. Based on the self-developed LAT system, binderless WC mold inserts with mirror finished surfaces are machined using the optimal parameters. PGM experiments of molding glass lenses for practical application are conducted to verify the machined mold inserts quality. The experiment results indicate that both the mold inserts and molded lenses with the required quality are achieved. Full article
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16 pages, 3260 KiB  
Article
Micromachining of Transparent Biocompatible Polymers Applied in Medicine Using Bursts of Femtosecond Laser Pulses
by Evaldas Kažukauskas, Simas Butkus, Piotr Tokarski, Vytautas Jukna, Martynas Barkauskas and Valdas Sirutkaitis
Micromachines 2020, 11(12), 1093; https://doi.org/10.3390/mi11121093 - 10 Dec 2020
Cited by 12 | Viewed by 3462
Abstract
Biocompatible polymers are used for many different purposes (catheters, artificial heart components, dentistry products, etc.). An important field for biocompatible polymers is the production of vision implants known as intraocular lenses or custom-shape contact lenses. Typically, curved surfaces are manufactured by mechanical means [...] Read more.
Biocompatible polymers are used for many different purposes (catheters, artificial heart components, dentistry products, etc.). An important field for biocompatible polymers is the production of vision implants known as intraocular lenses or custom-shape contact lenses. Typically, curved surfaces are manufactured by mechanical means such as milling, turning or lathe cutting. The 2.5 D objects/surfaces can also be manufactured by means of laser micromachining; however, due to the nature of light–matter interaction, it is difficult to produce a surface finish with surface roughness values lower than ~1 µm Ra. Therefore, laser micromachining alone can’t produce the final parts with optical-grade quality. Laser machined surfaces may be polished via mechanical methods; however, the process may take up to several days, which makes the production of implants economically challenging. The aim of this study is the investigation of the polishing capabilities of rough (~1 µm Ra) hydrophilic acrylic surfaces using bursts of femtosecond laser pulses. By changing different laser parameters, it was possible to find a regime where the surface roughness can be minimized to 18 nm Ra, while the polishing of the entire part takes a matter of seconds. The produced surface demonstrates a transparent appearance and the process shows great promise towards commercial fabrication of low surface roughness custom-shape optics. Full article
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10 pages, 2035 KiB  
Article
A Method to Determine the Minimum Chip Thickness during Longitudinal Turning
by Michal Skrzyniarz
Micromachines 2020, 11(12), 1029; https://doi.org/10.3390/mi11121029 - 24 Nov 2020
Cited by 15 | Viewed by 2123
Abstract
Micromachining, which is used for various industrial purposes, requires the depth of cut and feed to be expressed in micrometers. Appropriate stock allowance and cutting conditions need to be selected to ensure that excess material is removed in the form of chips. To [...] Read more.
Micromachining, which is used for various industrial purposes, requires the depth of cut and feed to be expressed in micrometers. Appropriate stock allowance and cutting conditions need to be selected to ensure that excess material is removed in the form of chips. To calculate the allowance, it is essential to take into account the tool nose radius, as this cutting parameter affects the minimum chip thickness. Theoretical and numerical studies on the topic predominate over experimental ones. This article describes a method and a test setup for determining the minimum chip thickness during turning. The workpiece was ground before turning to prevent radial runout and easily identify the transition zone. Contact and non-contact profilometers were used to measure surface profiles. The main aim of this study was to determine the tool–workpiece interaction stages and the cutting conditions under which material was removed as chips. Additionally, it was necessary to analyze how the feed, cutting speed, and edge radius influenced the minimum chip thickness. This parameter was found to be dependent on the depth of cut and feed. Elastic and plastic deformation and ploughing were observed when the feed rate was lower than the cutting edge radius. Full article
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13 pages, 2586 KiB  
Article
The Optimal Processing Parameters of Radial Ultrasonic Rolling Electrochemical Micromachining—RSM Approach
by Kailei He, Xia Chen and Minghuan Wang
Micromachines 2020, 11(11), 1002; https://doi.org/10.3390/mi11111002 - 13 Nov 2020
Cited by 1 | Viewed by 1964
Abstract
Radial ultrasonic rolling electrochemical micromachining (RUR-EMM) is a new method of electrochemical machining (ECM). By feeding small and rotating electrodes aided by ultrasonic rolling, an array of pits can be manufactured, which is called microstructures. However, there still exists the problem of choosing [...] Read more.
Radial ultrasonic rolling electrochemical micromachining (RUR-EMM) is a new method of electrochemical machining (ECM). By feeding small and rotating electrodes aided by ultrasonic rolling, an array of pits can be manufactured, which is called microstructures. However, there still exists the problem of choosing the optimal machining parameters to realize the workpiece machining with high quality and high efficiency. In the present study, response surface methodology (RSM) was proposed to optimize the machining parameters. Firstly, the performance criteria of the RUR-EMM are measured through investigating the effect of working parameters, such as applied voltage, electrode rotation speed, pulse frequency and interelectrode gap (IEG), on material removal amount (MRA) and surface roughness (Ra). Then, the experimental results are statistically analyzed and modeled through RSM. The regression model adequacies are checked using the analysis of variance. Furthermore, the optimal combination of these parameters has been evaluated and verified by experiment to maximize MRA and minimize Ra. The results show that each parameter has a similar and non-linear influence on the MRA and Ra. Specifically, with the increase of each parameter, MRA increases first and decreases when the parameters reach a certain value. On the contrary, Ra decreases first and then increases. Under the combined effect of these parameters, the productivity is improved. The experimental value of MRA and Ra is 0.06006 mm2 and 51.1 nm, which were 0.8% and 2.4% different from the predicted values. Full article
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16 pages, 5547 KiB  
Article
A 2D Waveguide Method for Lithography Simulation of Thick SU-8 Photoresist
by Zi-Chen Geng, Zai-Fa Zhou, Hui Dai and Qing-An Huang
Micromachines 2020, 11(11), 972; https://doi.org/10.3390/mi11110972 - 29 Oct 2020
Cited by 3 | Viewed by 2319
Abstract
Due to the increasing complexity of microelectromechanical system (MEMS) devices, the accuracy and precision of two-dimensional microstructures of SU-8 negative thick photoresist have drawn more attention with the rapid development of UV lithography technology. This paper presents a high-precision lithography simulation model for [...] Read more.
Due to the increasing complexity of microelectromechanical system (MEMS) devices, the accuracy and precision of two-dimensional microstructures of SU-8 negative thick photoresist have drawn more attention with the rapid development of UV lithography technology. This paper presents a high-precision lithography simulation model for thick SU-8 photoresist based on waveguide method to calculate light intensity in the photoresist and predict the profiles of developed SU-8 structures in two dimension. This method is based on rigorous electromagnetic field theory. The parameters that have significant influence on profile quality were studied. Using this model, the light intensity distribution was calculated, and the final resist morphology corresponding to the simulation results was examined. A series of simulations and experiments were conducted to verify the validity of the model. The simulation results were found to be in good agreement with the experimental results, and the simulation system demonstrated high accuracy and efficiency, with complex cases being efficiently handled. Full article
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20 pages, 6980 KiB  
Article
Model for Predicting the Micro-Grinding Force of K9 Glass Based on Material Removal Mechanisms
by Hisham Manea, Xiang Cheng, Siying Ling, Guangming Zheng, Yang Li and Xikun Gao
Micromachines 2020, 11(11), 969; https://doi.org/10.3390/mi11110969 - 29 Oct 2020
Cited by 5 | Viewed by 2591
Abstract
K9 optical glass has superb material properties used for various industrial applications. However, the high hardness and low fracture toughness greatly fluctuate the cutting force generated during the grinding process, which are the main factors affecting machining accuracy and surface integrity. With a [...] Read more.
K9 optical glass has superb material properties used for various industrial applications. However, the high hardness and low fracture toughness greatly fluctuate the cutting force generated during the grinding process, which are the main factors affecting machining accuracy and surface integrity. With a view to further understand the grinding mechanism of K9 glass and improve the machining quality, a new arithmetical force model and parameter optimization for grinding the K9 glass are introduced in this study. Originally, the grinding force components and the grinding path were analyzed according to the critical depth of plowing, rubbing, and brittle tear. Thereafter, the arithmetical model of grinding force was established based on the geometrical model of a single abrasive grain, taking into account the random distribution of grinding grains, and this fact was considered when establishing the number of active grains participating in cutting Nd-Tot. It should be noted that the tool diameter changed with machining, therefore this change was taking into account when building the arithmetical force model during processing as well as the variable value of the maximum chip thickness amax accordingly. Besides, the force analysis recommends how to control the processing parameters to achieve high surface and subsurface quality. Finally, the force model was evaluated by comparing theoretical results with experimental ones. The experimental values of surface grinding forces are in good conformity with the predicted results with changes in the grinding parameters, which proves that the mathematical model is reliable. Full article
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20 pages, 5965 KiB  
Article
Characterization of Stereolithography Printed Soft Tooling for Micro Injection Molding
by Daniel Dempsey, Sean McDonald, Davide Masato and Carol Barry
Micromachines 2020, 11(9), 819; https://doi.org/10.3390/mi11090819 - 28 Aug 2020
Cited by 27 | Viewed by 3582
Abstract
The use of microfeature-enabled devices, such as microfluidic platforms and anti-fouling surfaces, has grown in both potential and application in recent years. Injection molding is an attractive method of manufacturing these devices due to its excellent process throughput and commodity-priced raw materials. Still, [...] Read more.
The use of microfeature-enabled devices, such as microfluidic platforms and anti-fouling surfaces, has grown in both potential and application in recent years. Injection molding is an attractive method of manufacturing these devices due to its excellent process throughput and commodity-priced raw materials. Still, the manufacture of micro-structured tooling remains a slow and expensive endeavor. This work investigated the feasibility of utilizing additive manufacturing, specifically a Digital Light Processing (DLP)-based inverted stereolithography process, to produce thermoset polymer-based tooling for micro injection molding. Inserts were created with an array of 100-μm wide micro-features, having different heights and thus aspect ratios. These inserts were molded with high flow polypropylene to investigate print process resolution capabilities, channel replication abilities, and insert wear and longevity. Samples were characterized using contact profilometry as well as optical and scanning electron microscopies. Overall, the inserts exhibited a maximum lifetime of 78 molding cycles and failed by cracking of the entire insert. Damage was observed for the higher aspect ratio features but not the lower aspect ratio features. The effect of the tool material on mold temperature distribution was modeled to analyze the impact of processing and mold design. Full article
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15 pages, 7716 KiB  
Article
Molecular Dynamics Study of the Effect of Abrasive Grains Orientation and Spacing during Nanogrinding
by Nikolaos E. Karkalos and Angelos P. Markopoulos
Micromachines 2020, 11(8), 712; https://doi.org/10.3390/mi11080712 - 23 Jul 2020
Cited by 11 | Viewed by 2045
Abstract
Grinding at the nanometric level can be efficiently employed for the creation of surfaces with ultrahigh precision by removing a few atomic layers from the substrate. However, since measurements at this level are rather difficult, numerical investigation can be conducted in order to [...] Read more.
Grinding at the nanometric level can be efficiently employed for the creation of surfaces with ultrahigh precision by removing a few atomic layers from the substrate. However, since measurements at this level are rather difficult, numerical investigation can be conducted in order to reveal the mechanisms of material removal during nanogrinding. In the present study, a Molecular Dynamics model with multiple abrasive grains is developed in order to determine the effect of spacing between the adjacent rows of abrasive grains and the effect of the rake angle of the abrasive grains on the grinding forces and temperatures, ground surface, and chip formation and also, subsurface damage of the substrate. Findings indicate that nanogrinding with abrasive grains situated in adjacent rows with spacing of 1 Å leads directly to a flat surface and the amount of material remaining between the rows of grains remains minimal for spacing values up to 5 Å. Moreover, higher negative rake angle of the grains leads to higher grinding forces and friction coefficient values over 1.0 for angles larger than −40°. At the same time, chip formation is suppressed and plastic deformation increases with larger negative rake angles, due to higher compressive action of the abrasive grains. Full article
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15 pages, 4959 KiB  
Article
Jet Electrochemical Micromachining of Micro-Grooves with Conductive-Masked Porous Cathode
by Guochao Fan, Xiaolei Chen, Krishna Kumar Saxena, Jiangwen Liu and Zhongning Guo
Micromachines 2020, 11(6), 557; https://doi.org/10.3390/mi11060557 - 30 May 2020
Cited by 13 | Viewed by 2577
Abstract
Surface structures with micro-grooves have been reported to be an effective way for improving the performance of metallic components. Through-mask electrochemical micromachining (TMEMM) is a promising process for fabricating micro-grooves. Due to the isotropic nature of metal dissolution, the dissolution of a workpiece [...] Read more.
Surface structures with micro-grooves have been reported to be an effective way for improving the performance of metallic components. Through-mask electrochemical micromachining (TMEMM) is a promising process for fabricating micro-grooves. Due to the isotropic nature of metal dissolution, the dissolution of a workpiece occurs both along the width and depth. Overcut is generated inevitably with increasing depth, which makes it difficult to enhance machining localization. In this paper, a method of electrochemical machining using a conductive masked porous cathode and jet electrolyte supply is proposed to generate micro-grooves with high machining localization. In this configuration, the conductive mask is directly attached to the workpiece, thereby replacing the traditional insulated mask. This helps in achieving a reduction in overcut and an improvement in machining localization. Moreover, a metallic nozzle is introduced to supply a jetted electrolyte in the machining region with enhanced mass transfer via a porous cathode. The simulation and experimental results indicate that as compared with an insulated mask, the use of a conductive mask weakens the electric field intensity on both sides of machining region, which is helpful to reduce overcut and enhance machining localization. The effect of electrolyte pressure is investigated for this process configuration, and it has been observed that high electrolyte pressure enhances the mass transfer and improves the machining quality. In addition, as the pulse duty cycle is decreased, the dimensional standard deviation and roughness of the fabricated micro-groove are improved. The results suggest the feasibility and reliability of the proposed method. Full article
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15 pages, 3980 KiB  
Article
Functionalization of Plastic Parts by Replication of Variable Pitch Laser-Induced Periodic Surface Structures
by Leonardo Piccolo, Marco Sorgato, Afif Batal, Stefan Dimov, Giovanni Lucchetta and Davide Masato
Micromachines 2020, 11(4), 429; https://doi.org/10.3390/mi11040429 - 20 Apr 2020
Cited by 14 | Viewed by 3928
Abstract
Surface functionalization of plastic parts has been studied and developed for several applications. However, demand for the development of reliable and profitable manufacturing strategies is still high. Here we develop and characterize a new process chain for the versatile and cost-effective production of [...] Read more.
Surface functionalization of plastic parts has been studied and developed for several applications. However, demand for the development of reliable and profitable manufacturing strategies is still high. Here we develop and characterize a new process chain for the versatile and cost-effective production of sub-micron textured plastic parts using laser ablation. The study includes the generation of different sub-micron structures on the surface of a mold using femtosecond laser ablation and vario-thermal micro-injection molding. The manufactured parts and their surfaces are characterized in consideration of polymer replication and wetting behavior. The results of the static contact angle measurements show that replicated Laser-Induced Periodic Surface Structures (LIPSSs) always increase the hydrophobicity of plastic parts. A maximum contact angle increase of 20% was found by optimizing the manufacturing thermal boundary conditions. The wetting behavior is linked to the transition from a Wenzel to Cassie–Baxter state, and is crucial in optimizing the injection molding cycle time. Full article
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Other

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9 pages, 8653 KiB  
Technical Note
3D Printed Reconfigurable Modular Microfluidic System for Generating Gel Microspheres
by Xiaojun Chen, Deyun Mo and Manfeng Gong
Micromachines 2020, 11(2), 224; https://doi.org/10.3390/mi11020224 - 21 Feb 2020
Cited by 10 | Viewed by 5059
Abstract
Integrated microfluidic systems afford extensive benefits for chemical and biological fields, yet traditional, monolithic methods of microfabrication restrict the design and assembly of truly complex systems. Here, a simple, reconfigurable and high fluid pressure modular microfluidic system is presented. The screw interconnects reversibly [...] Read more.
Integrated microfluidic systems afford extensive benefits for chemical and biological fields, yet traditional, monolithic methods of microfabrication restrict the design and assembly of truly complex systems. Here, a simple, reconfigurable and high fluid pressure modular microfluidic system is presented. The screw interconnects reversibly assemble each individual microfluidic module together. Screw connector provided leak-free fluidic communication, which could withstand fluid resistances up to 500 kPa between two interconnected microfluidic modules. A sample library of standardized components and connectors manufactured using 3D printing was developed. The capability for modular microfluidic system was demonstrated by generating sodium alginate gel microspheres. This 3D printed modular microfluidic system makes it possible to meet the needs of the end-user, and can be applied to bioassays, material synthesis, and other applications. Full article
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