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Micro/meso-scale mechanical machining (M4) processes are miniaturized versions of conventional machining processes such as milling, drilling, and turning, where material removal is accomplished by physical contact between the micro/meso-scale cutting tool and the workpiece. The objective of this review paper is to provide an assessment of the state-of-the-field related to M4 processes during the last two decades. Key systems-level issues related to the deployment of M4 processes including micro/meso-scale machine tool (mMT) design, sensing/calibration, cutting tools, and lubrication strategies are discussed. Emerging material systems are identified along with the specific challenges posed for the development of microstructure-based process models. The topic of micro/meso-scale machining dynamics is reviewed both in terms of recent research findings as well as unresolved challenges posed by the complexity of experimental characterization and modeling. Finally, key industry trends are discussed along with promising interdisciplinary drivers that are expected to influence this field in the upcoming decade. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanistic modeling of micro end milling forces, with consideration of the effects of plowing, elastic recovery, effective rake angle, and flank face rubbing. Two different mechanistic models are developed for shearing- and plowing-dominant regimes. Micro end milling experiments are conducted to validate the model for Aluminum 6061; and, the model appropriately predicts force profiles for a wide range of feed rates, and prediction of the root mean square (RMS) values of the resultant forces is, on average, within a 12% error. The study of the model shows that plowing and rubbing force contributions are significant, especially at low feed rates. The edge radius is found to have a significant effect on plowing and rubbing force components and the effective rake angle, which indicates that it is important to maintain a low edge radius to reduce micro end milling forces. [ABSTRACT FROM AUTHOR]

This paper investigates a thread making process called thrilling, which performs both drilling and thread milling with one tool. A chip thickness and mechanistic cutting force model has been developed for a thread milling operation with a thrilling tool. The model considers the complex geometry of a thrilling tool and the unique tool paths associated with the thread milling operation. Experiments have been conducted to validate the developed model. Comparison of the average torque and forces between experiment and simulation results shows that the model predicts the experimental results within 12% error. [ABSTRACT FROM AUTHOR]

An atomization-based cutting fluid application system is developed for micro-end milling. The system was designed to ensure spreading of the droplets on the workpiece surface based on the analysis of the atomized droplet impingement dynamics. The results of the initial experiments conducted to examine the viability of the system show that the cutting forces are lower and tool life is significantly improved with the atomized cutting fluids when compared to dry and flood cooling methods. Also, application of atomized cutting fluid is found to result in good chip evacuation and lower cutting temperature. Experiments were also conducted to study the effect of fluid properties on cutting performance, and the results show that cutting fluids with lower surface tension and higher viscosity perform better in terms of cutting forces. [ABSTRACT FROM AUTHOR]

A piezoelectrically driven, submicron XY-positioning stage with multiprocess capability is developed and then integrated into two micro/nanoscale manufacturing processes to improve their performance. The design is based on the HexFlex™ mechanism but is modified to improve structural robustness using a combination of factorial design, linear programming, and finite element analysis. Performance analysis reveals travel ranges of 16 µm (X-axis) and 8 µm (Y-axis), positioning accuracies of 87 nm (X-axis) and 92 nm (Y-axis), and overall stiffnesses of 32 N/µm (X-axis) and 36 N/µm (Y-axis). A comparison of microfluidic channels manufactured with a micromachine tool (mMT) alone and with the stage stacked on the mMT shows an improvement in feature accuracy from 870 nm to 170 nm. The stage is integrated with an electrochemical deposition setup. Nanowire structures with sharp angles are fabricated. The diameter of these nanowires shows an improvement in uniformity by decreasing the standard deviation of diameter variation from 2.088 µm to 0.009 µm. [ABSTRACT FROM AUTHOR]

An acoustic emission-based touch-off detection system has been developed to determine contact between a rotating microtool and a workpiece surface with micron-level accuracy. The system has been implemented on an existing three-axis microscale machine tool. The system has been tested with microendmills as small as 50 µm in diameter and microdrills as small as 254 µm in diameter. The accuracy of the system has been found to depend on tool geometry and workpiece surface characteristics and is generally on the order of 1 µm. An analytical model has been constructed to predict touch-off detection error. The calibrated model has been shown to predict surface overshoot and undershoot trends quite well. Simulations have shown that touch-off error is dominated by part surface roughness. [ABSTRACT FROM AUTHOR]

In microend milling, due to the comparable size of the edge radius to chip thickness, chip formation mechanisms are different. Also, the design of microend mills with features of a large shank, taper, and reduced diameter at the cutting edges introduces additional dynamics and faults or errors at the cutting edges. A dynamic microend milling cutting force and vibration model has been developed to investigate the microend milling dynamics caused by the unique mechanisms of chip formation as well as the unique microend mill design and its associated fault system. The chip thickness model has been developed considering the elastic-plastic nature in the ploughing process. A slip-line field modeling approach is taken for a cutting force model development that accounts for variations in time effective rake angle and dead metal cap. Time process fault parameters associated with microend mills have been defined amid their effects on chip load have been derived. Finally, a dynamic model has been developed considering time effects of both time unique microend mill design and fault system and factors that become significant at high spindle speeds including rotary inertia amid gyroscopic moments. [ABSTRACT FROM AUTHOR]

In Part II of this paper experimental and analytical methods have been developed to estimate the values of the process faults defined in Part I of this paper. The additional faults introduced by the microend mill design are shown to have a significant influence on the total net runout of the microend mill. The dynamic model has been validated through microend milling experiments. Using the dynamic model, the effects of minimum chip thickness and elastic recovery on microend milling stability have been studied over a range of feed rates for which the cutting mechanisms vary from ploughing-dominated to shearing-dominated. The minimum chip thickness effect is found to cause feed rate dependent instability at low feed rates, and the range of unstable feed rates depends on the axial depth of cut. The effects of process faults on microend mill vibrations have also been studied and the influence of the unbalance from the faults is found to be significant as spindle speed is increased. The stability characteristics due to the regenerative effect have been studied. The results show that the stability lobes from the second mode of the microend mill, which are generally neglected in macroscale end milling, affect the microend mill stability significantly. [ABSTRACT FROM AUTHOR]