Advances in Micro and Nano Manufacturing: Process Modeling and Applications

Micro- and nanomanufacturing technologies have been researched and developed in the industrial environment with the goal of supporting product miniaturization and the 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 nanoscale technologies require the study of different mechanical, thermal, and fluid dynamics, phenomena which need to be assessed and modeled.This Special Issue is dedicated to advances in the modeling of micro- and nanomanufacturing processes. The development of new models, validation of state-of-the-art modeling strategies, and approaches to material model calibration are presented. The goal is to provide state-of-the-art examples of the use of modeling and simulation in micro- and nanomanufacturing processes, promoting the diffusion and development of these technologies

A review on conventional and nonconventional machining of SiC particle-reinforced aluminium matrix composites

AbstractAmong the various types of metal matrix composites, SiC particle-reinforced aluminum matrix composites (SiCp/Al) are finding increasing applications in many industrial fields such as aerospace, automotive, and electronics. However, SiCp/Al composites are considered as difficult-to-cut materials due to the hard ceramic reinforcement, which causes severe machinability degradation by increasing cutting tool wear, cutting force, etc. To improve the machinability of SiCp/Al composites, many techniques including conventional and nonconventional machining processes have been employed. The purpose of this study is to evaluate the machining performance of SiCp/Al composites using conventional machining, i.e., turning, milling, drilling, and grinding, and using nonconventional machining, namely electrical discharge machining (EDM), powder mixed EDM, wire EDM, electrochemical machining, and newly developed high-efficiency machining technologies, e.g., blasting erosion arc machining. This research not only presents an overview of the machining aspects of SiCp/Al composites using various processing technologies but also establishes optimization parameters as reference of industry applications

Design and Fundamental Understanding of Minimum Quantity Lubrication (MQL) Assisted Grinding Using Advanced Nanolubricants

Abrasive grinding is widely used across manufacturing industry for finishing parts and components requiring smooth superficial textures and precise dimensional tolerances and accuracy. Unlike any other machining operations, the complex thermo-mechanical processes during grinding produce excessive friction-induced energy consumption, heat, and intense contact seizures. Lubrication and cooling from grinding fluids is crucial in minimizing the deleterious effects of friction and heat to maximize the output part quality and process efficiency. The conventional flood grinding approach of an uneconomical application of large quantities of chemically active fluids has been found ineffective to provide sufficient lubrication and produces waste streams and pollutants that are hazardous to human health and environment. Application of Minimum Quantity Lubrication (MQL) that cuts the volumetric fluid consumption by 3-4 orders of magnitude have been extensively researched in grinding as a high-productivity and environmentally-sustainable alternative to the conventional flood method. However, the lubrication performance and productivity of MQL technique with current fluids has been critically challenged by the extreme thermo-mechanical conditions of abrasive grinding. In this research, an MQL system based on advanced nanolubricants has been proposed to address the current thermo-mechanical challenges of MQL grinding and improve its productivity. The nanolubricants were composed of inorganic Molybdenum Disulphide nanoparticles (≈ 200 nm) intercalated with organic macromolecules of EP/AW property, dispersed in straight (base) oils - mineral-based paraffin and vegetable-based soybean oil. After feasibility investigations into the grindability of cast iron using MQL with nanolubricants, this research focused on the fundamental understanding of tribological behavior and lubricating mechanisms of nanolubricants as a method to improve the productivity of MQL-assisted surface grinding of ductile iron and alloy steel. An extensive investigation on MQL-assisted grinding using vitrified aluminum oxide wheel under varied infeed and lubrication condition was carried out with the scope of documenting the process efficiency and lubrication mechanisms of the nanolubricants. Experimental results showed that MQL grinding with nanolubricants minimized the non-productive outputs of the grinding process by reducing frictional losses at the abrasive grain-workpiece interfaces, energy consumption, wheel wear, grinding zone temperatures, and friction-induced heat generation. Use of nanolubricants in MQL yielded superior productivity by producing surface roughness as low as 0.35 μm and grinding efficiencies that were four times higher as compared to those obtained from flood grinding. Repeatable formation of tribochemical films of antifriction, antiwear, and extreme pressure chemical species in between the contact asperities of abrasive crystals and work material was identified with nanolubricants. The tribological behavior was characterized by this synergistic effect of the antiwear, antifriction, and load carrying chemical species that endured grain-workpiece seizures and reduced adhesion friction between the contact surfaces. Delivery of organic coated Molybdenum Disulphide nanoparticles by anchoring on the natural porosity of the abrasive wheel and eventually, sliding-induced interfacial deformation into tribolayers and alignment at the grinding zone were established as the lubrication mechanisms of the nanolubricants. These mechanisms were further validated from tribological evaluations of lubricated cubic boron nitride (cBN) superabrasives-1045 steel sliding pairs on a reciprocating tribotest rig resembling the tool-lubricant-workpiece interactions of MQL-assisted grinding

Micro-grinding of titanium

Titanium and its alloys are difficult-to-cut materials, commonly used in several application fields, such as: medicine, aerospace, automotive and turbine manufacturing due to their biocompatibility, corrosion resistance, excellent mechanical and thermal properties, and light weight. However, its machining is associated with several difficulties, such as high tool wear, low surface quality, high cutting forces and high costs. To overcome these problems, using a proper and efficient manufacturing process seems essential. Micro-grinding provides a competitive edge in the fabrication of small-sized features and parts with superior surface quality compared with other processes. The quality aspects such as surface integrity of the parts produced by micro-grinding is influenced by various factors related to the induced mechanical and thermal loads during the process. Therefore, the machining parameters must be carefully chosen and controlled. Hence, developing an advanced, highly effective and efficient method, which can produce high quality micro-parts without inducing sub-surface damage, seems essential.In this study, experimental and analytical investigations on 2D micro-grinding of titanium are presented. The run-out of micro-tools can be affected by the relatively high forces induces by mechanical dressing, meaning that the dressing and tool-conditioning possibilities are limited. Therefore, a proper set of dressing parameters is obtained for dressing of micro-grinding tools. An analytical model, which considers grits interaction, heat transfer and actual micro-grinding tool topography is developed which is able to predict the surface roughness and cutting forces for a given set of dressing and grinding parameters. It is shown that the topography of the tool varies with changing the dressing parameter which affects the grinding forces and surface roughness. In the analytical model the actual topography of the tool is considered in the simulation for the first time.\ua0 Additionally, the model is able to determine grinding parameters that generate minimum surface roughness with minimizing the grinding forces. To determine the correct chip thickness with the maximum material removal rate, an appropriate grinding tool and optimum process parameters to generate highly accurate contours in a micron scale will be further analyzed. Using the analytical model, the effects of process parameters and tool surface topography are mapped to the process outputs, i.e. surface roughness and grinding forces. The results show that the analytical model enables the prediction of micro-grinding forces with a total error of 13.5% and surface roughness with the total error of 16%. The simulation results match with the experimental results to a greater degree in the low cutting speed range, rather than at higher cutting speeds. The results also indicate that the dressing parameters, such as the dressing overlap ratio and the speed ratio are influential factors, affecting surface roughness and grinding forces. Using higher values of dressing overlap ratio (Ud up to 1830) reduced the surface roughness, however, leads to approximately 70% higher cutting forces. The observed 40% reduction in the grinding forces is achieved by increasing the cutting speed from 6 to 14 m/s, but this increases the surface roughness. Higher values of the dressing overlap ratio reduce the chip cold-welding on the abrasive grains and causes less loading of the tool in form of chip nests. Welded clogging of the grinding pin at lower Ud values deteriorates the surface quality resulting in increased surface roughness. Using the up-dressing method leads to lower chip loading over the surface of the grinding tool, which improves the ground surface. Moreover, the down-dressing of micro-grinding pins results in higher value of surface roughness and lower grinding forces compared with up-dressing

Microgrinding of Ceramic Materials.

Ceramic micro-components are becoming increasingly important in various industrial fields, as they not only allow manufacturers to reduce product size, but also provide many attractive properties, such as good chemical stability, high hardness and strength. Featured with high machining flexibility, miniature tool-based microgrinding is a new technology to manufacture ceramic micro-components, but it lacks comparable knowledge-based research that can be drawn on to optimize the process. This research addresses this barrier through conducting fundamental studies in ceramic microgrinding in the grinding force prediction, surface generation modeling and tool wear mechanism study. Grinding force prediction is important for improving the dimensional accuracy in microgrinding of ceramic materials. Based on cohesive zone finite element analysis, this study investigates grinding force modeling and prediction in ceramic microgrinding by modeling the actual chip generation process. The chip generation is explicitly simulated based on actual diamond cutting edge profile. It was observed that the tool stiffness has a significant influence on the grinding force prediction. In grinding of ceramic materials, surface texture is generated by both ductile material flow and surface chipping. By considering these two mechanisms, this study proposes a surface generation model for microgrinding of ceramic materials. It was observed that the predicted surface roughness matches well with the experiment results. At high feed rates and depths of cut, the vibration effect could result in more prediction error. To understand the influence of tool wear in microgrinding of ceramic materials, individual diamonds on a microgrinding tool were tracked for their detail wear process. It was observed that their wear mechanisms have specific influences on the surface generation, and attrition wear is dominant when the grinding process is stable. By applying water based coolant, the microgrinding tool wear can be reduced. It was also observed that the process signals in microgrinding are influence by both tool wear and tool deflection due to the low tool stiffness.Ph.D.Mechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75957/1/jiefeng_1.pd

An experimental investigation of ultrasonic assisted milling (UAM) of carbon fibre reinforced polymer (CFRP) and the effect of machining on the BMI 5250-4 matrix resin

Milling of Carbon Fibre Reinforced Polymer (CFRP) is necessary for component accuracy prior to assembly of aircraft. Recently, ultrasonic assisted milling (UAM) which combines conventional machining (CM) with ultrasonic vibration on the cutting tool, has shown beneficial outcomes with respect to the machinability of some metals, however, limited UAM of CFRP has been reported. In this thesis, milling (CM and UAM) of a CFRP incorporating Bismaleimide 5250-4 (BMI 5250-4) resin was carried out in a wide range of cutting parameters and environments (dry, conventional cutting fluid (CCF) and CO2 cryogenic). Machinability was examined in terms of tool wear, cutting forces and surface roughness. In terms of machinability with conventional cutting tools, machining in a CO2 had a positive effect on tool life, despite an increase in cutting forces, compared to CCF and dry. UAM was found to reduce cutting forces by up to 10 %, compared with CM, however, this did not yield any benefit in terms of tool wear and/or workpiece surface roughness. When dry machining employing an abrasive diamond tool, CFRP material adhesion was a feature. The application of UAM in this instance yielded, reduced workpiece adhesion on the cutting tool and improved workpiece surface roughness. Machining of CFRP must be performed below the glass transition temperature (Tg) of the resin to avoid the degradation of the properties of the matrix resin. In this research new findings in the temperature initiated during machining and the consequential effects on the polymer utilised Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) which is well established in polymer characterization. FTIR and DSC was carried out to investigate the effect of machining on the chemical and material properties of BMI 5250-4 such as Tg and changes to matrix resin chemical bonding, which has been closely associated with degradation of the machined part. Further analysis of the machined surface by DSC indicated that the Tg of the matrix resin had been exceeded during the machining process and led to degradation of the BMI 5250-4 in some cases. An observed reduction of the maleimide double bond (C=C) at 825 cm-1 wavelength by FTIR signified that further post-curing of BMI 5240-4 had occurred which suggested that a higher cutting temperature was developed at the machine tool tip than recorded with the infrared camera. CM dry machining, FTIR analysis also confirmed the formation of isocyanate-derived products (C≡N) at 2250 cm-1 wavelength, a bond associated with the point at which BMI 5240-4 is thermally degraded having experienced temperatures in the range 400 to 600 °C. This result suggests that when CM dry machining the actual cutting temperature experienced by the BMI 5240-4 was at least 400 °C. The formation of isocyanate-derived products was not observed for UAM dry machining, suggesting that ultrasonic vibration of the cutting tool may reduce the cutting temperature in the primary shear zone, however this temperature reduction was insufficient to arrest observed post curing effects and shift in the Tg. Other aspects of the FTIR analysis revealed that despite the improvements to workpiece surface roughness when milling with CCF there was an increased presence of moisture (-OH bond) in the BMI 5240-4 resin which may have a detrimental effect on the durability of the material over time. Machining CFRP has been enhanced by the introduction of the chemical analysis. It suggests that DSC and FTIR exploration of the thermal history of the CFRP can provide more information about the temperature than typical thermal measurement during machining such as thermal cameras and thermocouples. The management of the milling process of CFRP can now be related to the management of the temperature at the tool tip and the effect on polymer characteristics. As a consequence, milling of CFRP in CO2 exhibited improvement in tool wear, an observed reduction in cutting temperature, and sustenance of the chemical properties of BMI 5250-4. However, there was no significant benefit in additionally employing UAM in a CO2 environment. The research has provided a new insight in the milling of polymer composites and could be beneficial in avoiding thermal degradation of the machined part, maintaining the quality of machined part and avoiding scrap parts at the end of machining processes

Investigation into vibration assisted micro milling: theory, modelling and applications

PhD ThesisPrecision micro components are increasingly in demand for various engineering industries, such as biomedical engineering, MEMS, electro-optics, aerospace and communications. The proposed requirements of these components are not only in high accuracy, but also in good surface performance, such as drag reduction, wear resistance and noise reduction, which has become one of the main bottlenecks in the development of these industries. However, processing these difficult-to-machine materials efficiently and economically is always a challenging task, which stimulates the development and subsequent application of vibration assisted machining (VAM) over the past few decades. Vibration assisted machining employs additional external energy sources to generate high frequency vibration in the conventional machining process, changing the machining (cutting) mechanism, thus reducing cutting force and cutting heat and improving machining quality. The current awareness on VAM technology is incomplete and effective implementation of the VAM process depends on a wide range of technical issues, including vibration device design and setup, process parameters optimization and performance evaluation. In this research, a 2D non-resonant vibration assisted system is developed and evaluated. Cutting mechanism and relevant applications, such as functional surface generation and microfluidic chips manufacturing is studies through both experimental and finite element analysis (FEA) method. A new two-dimensional piezoelectric actuator driven vibration stage is proposed and prototyped. A double parallel four-bar linkage structure with double layer flexible hinges is designed to guide the motion and reduce the displacement coupling effect between the two directions. The compliance modelling and dynamic analysis are carried out based on the matrix method and lagrangian principle, and the results are verified by finite element analysis. A closed loop control system is developed and proposed based on LabVIEW program consisting of data acquisition (DAQ) devices and capacitive sensors. Machining experiments have been carried out to evaluate the performance of the vibration stage and the results show a good agreement with the tool tip trajectory simulation results, which demonstrates the feasibility and effectiveness of the vibration stage for vibration assisted micro milling. The textured surface generation mechanism is investigated through both modelling and experimental methods. A surface generation model based on homogenous matrices transformation is proposed by considering micro cutter geometry and kinematics of vibration assisted milling. On this basis, series of simulations are performed to provide insights into the effects of various vibration parameters (frequency, amplitude and phase difference) on the generation mechanism of typical textured surfaces in 1D and 2D vibration-assisted micro milling. Furthermore, the wettability tests are performed on the machined surfaces with various surface texture topographies. A new contact model, which considers both liquid infiltration effects and air trapped in the microstructure, is proposed for predicting the wettability of the fish scales surface texture. The following surface textures are used for T-shaped and Y-shaped microchannels manufacturing to achieve liquid one-way flow and micro mixer applications, respectively. The liquid flow experiments have been carried out and the results indicate that liquid flow can be controlled effectively in the proposed microchannels at proper inlet flow rates. Burr formation and tool wear suppression mechanisms are studied by using both finite element simulation and experiment methods. A finite element model of vibration assisted micro milling using ABAQUS is developed based on the Johnson-Cook material and damage models. The tool-workpiece separation conditions are studied by considering the tool tip trajectories. The machining experiments are carried out on Ti-6Al-4V with coated micro milling tool (fine-grain tungsten carbides substrate with ZrO2-BaCrO4 (ZB) coating) under different vibration frequencies (high, medium and low) and cutting states (tool-workpiece separation or nonseparation). The results show that tool wear can be reduced effectively in vibration assisted micro milling due to different wear suppression mechanisms. The relationship between tool wear and cutting performance is studied, and the results indicate that besides tool wear reduction, better surface finish, lower burrs and smaller chips can also be obtained as vibration assistance is added

Heat Assisted Machining of Nickel Base Alloys: Experimental and Numerical Analysis

Nickel base alloys are frequently used in aerospace industries, marine, biomedical application and other demanding industries due to their high strength, high hardness, resistant to corrosion and ability to withstand at elevated temperature. But machining of these materials in conventional way impairs severely their machinability due to certain inherent properties like low thermal conductivity, high chemical affinity and presence of hard particles in the microstructure etc. Therefore, tool life is reduced, due to the abrasion wear from the hard particles and high temperature of the tool-chip interface due to diffusion wear during machining of nickel base alloys. In this work, hot machining is introduced for processing of nickel base alloys like Inconel 718, Inconel 625, and Monel 400. In this technique, heating on the workpiece is combined with conventional turning process was used to enhanced machinability of nickel base alloy without compromise quality and productive. The study revealed that the influence of the workpiece temperature on the workpiece surface enhanced machining performance in terms of better surface finish, MRR, and reduction of forces, wear compared to conventional turning process. The surface integrity has been studied in terms of surface roughness, and microhardness beneath the machined surface in hot machining operation. Finite element modeling was also employed to prediction of cutting force, temperature distribution, stress, in hot turning of Inconel 718. The finite element results were compared with the experimental value and close agreement was found. In any industries production of parts along with tool life, surface finish is the major concern. In order to optimize the machining of nickel base alloys, optimization technique was performed using desirability and principal component analysis. Finally, machinability comparison was made between three materials, in order to understand effect of machining parameters along with workpiece temperature. In the literature, no research studies were found on flame heat machining of nickel base alloys (Inconel 625, Inconel 718 and Monel 400). The research led to various contributions to finding in terms of experimental investigation, optimization and FEM modeling. The contribution of the thesis should be of interest who works in the areas of machining of hard materials

Modeling and simulation of surface generation in manufacturing

The paper describes the state-of-the-art in modeling and simulation of surface texture and topography generation at micro and nano dimensional scales. Three main classes of manufacturing processes used for the generation of engineering surfaces are considered: material removal processes, material conservative processes, and material additive processes. Types of modeling techniques for the simulation of surface generation are reviewed and discussed including analytical models, numerical multi-physics models, and data-driven methods. After presenting the application of those modeling techniques for the prediction of characteristics and geometry of surfaces generated by different manufacturing processes, their performance, implementation, and accuracy are discussed. Finally, a roadmap for the realization of a complete surface generation digital twin in manufacturing is outlined

Vibration assisted machining: Modelling, simulation, optimization, control and applications

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 30/11/2010.Increasing demand for precision components made of hard and brittle materials such as glasses, steel alloys and advanced ceramics, is such that conventional grinding and polishing techniques can no longer meet the requirements of today's precision manufacturing engineering. Particularly, in order to undertake micro-milling of optical glasses or other hard-machining materials, vibration assisted machining techniques have been adopted. However, it is essential and much needed to undertake such processes based on a scientific approach, i.e. the process to be quantitatively controlled and optimized rather than carried out with a trial-and-error manner. In this research, theoretical modelling and instrumental implementation issues for vibration assisted micro-milling are presented and explored in depth. The modelling is focused on establishing the scientific relationship between the process variables such as vibration frequency, vibration amplitude, feedrate and spindle speed while taking into account machine dynamics effect and the outcomes such as surface roughness generated, tool wear and material removal rate in the process. The machine dynamics has been investigated including a static analysis, machine tool-loop stiffness, modal analysis, frequency response function, etc, carried out for both the machine structure and the piezo-actuator device. The instrumentation implementation mainly includes the design of the desktop vibration assisted machining system and its control system. The machining system consists of a piezo-driven XY stage, air bearing spindle, jig, workpiece holder, PI slideway, manual slideway and solid metal table to improve the system stability. The control system is developed using LabVIEW 7.1 programming. The control algorithms are developed based on theoretical models developed by the author. The process optimisation of vibration assisted micro-milling has been studied by using design and analysis of experiment (DOE) approach. Regression analysis, analysis of variance (ANOVA), Taguchi method and Response Surface Methodology (RSM) have been chosen to perform this study. The effects of cutting parameters are evaluated and the optimal cutting conditions are determined. The interaction of cutting parameters is established to illustrate the intrinsic relationship between cutting parameters and surface roughness, tool wear and material removal rate. The predicted results are confirmed by validation experimental cutting trials. This research project has led to the following contribution to knowledge: (1) Development of a prototype desktop vibration assisted micro-milling machine. (2) Development of theoretical models that can predict the surface finish, tool wear and material removal rate quantitatively. (3) Establishing in depth knowledge on the use of vibration assisted machining principles. (4) Optimisation of cutting process parameters and conditions through simulations and machining trials for through investigation of vibration assisted machining.Financial support was obtained from Brunel University