Small-scale Machine Research Articles

롤압연, 압출, 단조 등 전통 기계가공법의 모사 응용을 통한 다양한 나노패턴의 대면적 연속생산 기술 구현

We present a series of simple but novel nanopatterning methodologies inspired by traditional mechanical machining processes involving rolling, pullout, and forging. First, we introduce roll-to-roll nanopatterning, which adapts conventional rolling for continuous nanopatterning. Then, nano-inscribing and nano-channel lithography are demonstrated, whereby seamless nanogratings can be continuously pulled out, as in a pullout process. Finally, we discuss vibrational indentation micro- and nanopatterning. Similarly to the forging/indentation process, this technique employs high-frequency vertical vibration to indent periodic micro/nanogratings onto a horizontally fed substrate. We discuss the basic principles of each process, along with its advantages, disadvantages, and potential applications. Adopting mature and reliable traditional technologies for small-scale machining may allow continuous nanopatterning techniques to cope with scalable and low-cost nanomanufacturing in a more productive and trustworthy way.

Everyday Technology: Machines and the Making of India’s Modernity, by David Arnold

David Arnold begins the epilogue to his study of everyday technology in India by referring to Arundhati Roy’s prize-winning novel, The God of Small Things. Small things can be ‘godly’ in the sense of ‘being of primary, even paramount, importance when it comes to daily lives and the everyday objects with which people surround themselves’ (p. 173). In Arnold’s view, scholarship concerning the history of technology in India has, thus far, focused too heavily on the ‘big’: on large-scale technological schemes such as railways, telegraphs, irrigation and electrification. While such schemes undoubtedly had a transformative effect on India, scholars have failed to recognise the similarly significant role played by small-scale technologies in the transformation of Indian economy, society and culture. The book, which covers the period from the 1880s to the 1960s, seeks to displace Eurocentric histories of ‘big’ technology by investigating the ways in which small-scale machines (in particular typewriters, sewing machines, bicycles and rice mills) were sold, used and imagined in the Indian context. While histories of large-scale technological schemes in India have tended, often understandably, to interpret technological power as emerging in the West before being transplanted to other regions in the world, an investigation of small-scale technologies allows historians to appreciate more fully the ways in which global commodities were not only transformative of, but also transformed by, the local contexts in which they were put to use.

Effect of surface non-flatness on the lubrication characteristics in the valve part of a swash-plate type axial piston pump

The objective of this application study was to investigate the effect of surface non-flatness on the lubrication characteristic of the bearing/sealing part between cylinder barrel and valve plate in a hydrostatic axial piston pump. A developed numerical algorithm facilitated the simultaneous calculation of time-varying cylinder pressure, rotating body motion, and fluid film pressure to observe fluid film geometry and power loss. It was shown that an ideally flat surface might not form full fluid lubrication film properly, and that small-scale machining error, surface waviness, may increase the film thickness to some degree. The shape model of surface waviness considered waviness unit shape as well as its surface lay. However the results demonstrated that surface non-flatness of such small scale did not form the desirable fluid film geometry which minimized the power loss yet. Providing some surface design tips, two particular curved surfaces whose pressure-generating mechanisms differ were selected and analyzed in variation with their shapes and operating conditions. This study asserted that a circumferentially wavy surface would make better performance of motion stability and power efficiency than a radially wedged land surface, and finally that the non-flatness design strategy should be applied with re-considering the clamping ability.

Manufacturing system simulation for evaluation of productivity and energy consumption

Industries need to concurrently evaluate productivity and energy consumption when designing and improving manufacturing systems. Manufacturing system simulations to evaluate productivity have often been used. However, manufacturing system simulations to concurrently evaluate productivity and energy consumption have not been proposed. The purpose of our research is to establish a system for concurrent evaluation of productivity and energy consumption in a manufacturing system simulation. First, in this study, necessary items and requirements to evaluate productivity and energy consumption are analysed. Secondly, a prior evaluation system considering the necessary items and the requirements is proposed. A state transition model for facilities, a simulation system and a visualization system are proposed to realize the prior evaluation system. Finally, case studies for a small-scale machining line and a middle-scale semiconductor manufacturing line are carried out to confirm the efficiency of our proposed prior evaluation system.

Research on Job Shop Scheduling Technique in Small-Scale Machine Production

According to the characteristics of the small-scale machine production, a job shop scheduling technique was given in this paper. In the technique, two classes of queues were built. The job queue expresses the procedures of a job. The machine queue expresses the actual processing sequence of the jobs on a machine. At first, all job queues could be built and the sequence of the operations in them should not be changed forever; all machine queues are null. The completion rate of each operation is defined. The core task of the technique are prioritizing the operation which the completion rate is the smallest of the job queues inserting into a machine queue, and minimize the finish time of the last operation in all machine. The technique could always achieve good job shop schedules. The feasibility and availability of the technique is verified through an example.

Experimental Verification of a Combi-Bearing Model for Vertical Rotor Systems

Combi-bearing is a combined thrust-journal bearing design used in vertical hydropower rotors. The dynamic characteristics of this component (combi-bearing) were analytically modeled by Luneno et al. (2011, “Model Based Analysis of Coupled Vibrations Due to the Combi-Bearing in Vertical Hydroturbogenerator Rotors,” ASME J. Vib. Acoust., 133, p. 061012). This analytic model was inserted into a finite element model of a vertical rotor rig and numerically simulated. In this paper, the simulated vertical rotor-bearings system is a small-scale vertical machine constructed to validate the analytically derived combi-bearing model. Good agreement was found between the simulation and experimental results. The simulation and experimental results showed that the journal (radial) bearing's position relative to the contact point between the combi-bearing's collar and the rotor influences the rotor system's fundamental natural frequencies. Therefore, the combi-bearing model needs to be included into rotor dynamic models. Neglecting the effect of this component may cause significant errors in the predicted results.

Observations of Ablation Dynamics in Wire-Array $Z$-Pinch Experiments on the Llampüdkeñ Generator

Wire-array Z-pinch experiments have been performed on the Llampüdkeñ generator (~470 kA in ~410 ns) [Chuaqui et al., Laser Part. Beams 15, 241 (1997)] using an overmassed load of aluminum wires. Time-resolved optical laser schlieren and extreme ultraviolet imaging were used in order to study the plasma ablation dynamics. The results show the formation and subsequent ablation of plasma from the wires, followed by the appearance of a precursor plasma column on the axis. According to these results and to the rocket model of wire ablation, an ablation velocity of (1.7-2.6) × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> m/s is estimated, which is larger than those obtained in faster generators. Additionally, the main resemblances and differences with previous experiments are presented, allowing in this way to open the study of this configuration in smaller scale machines.

Evaluation of accuracy and reproducibility of the optical measuring system in cast machine tool body assessment

Evaluation of accuracy and reproducibility of the optical measuring system in cast machine tool body assessment The hereby presented study puts forth the fundamentals of an innovative technology enabling rapid assessment of machine tool cast shape by elimination of manual marking out requirement and machining surplus minimization. The new technique is based on optical measuring system utilization for the design of virtual cast models and their comparative analysis with structural models. Two small scale machine tool body casts were selected for the investigation. The measurements were conducted in triplicate series for each cast labeled with reference markers, by means of Atos GOM II optical scanner. For further comparison, one of the casts was additionally scanned without labeling. Flatness parameters of selected cast surfaces were determined for geometric accuracy evaluation and the scanned cast shapes were compared with reference models. The comparison results were recorded as multicolored maps projected upon the experimental cast and reference model surfaces. Practical map interpretation was further elucidated and the surplus sizes on the machined surfaces were assessed accordingly. Comparative analyses of individual models were demonstrated for all measurement series of both casts, affording reproducibility evaluation of optical scanning system measurements. Economic viability of the proposed technology market implementation was unequivocally established, as it provides for considerable reduction in the cast machining scale as well as the quality control of 100%.

Development of a Small Scale Machine for Recovering Bush Mango Kernel from Bush Mango Nut

A small scale machine for recovering bush mango kernel from bush mango nut was designed, constructed and tested. Consideration was given to the techno-economic status of the micro and small scale bush mango processors living in the rural communities who are the intended users of the machine. The functional parts of the machine included feeding unit, cracking unit, winnowing unit and frame. The machine was tested with processed and unprocessed bush mango nuts and results showed that average cracking efficiency of 57.3 % and 19.3 % respectively were obtained. Powered by a 3 hp single-phase electric motor, the machine was constructed with readily available materials. It is recommended that, before cracking, bush mango should be processed by completely removing the fibrous mesocarp as this improves the efficiency of cracking and separation.

Application of exergy balances for the optimization of non-adiabatic small turbomachines operation

In the current context of global warming due to CO 2 (carbon dioxide) emissions, mainly produced by power plants and road transportation, it is imperative to optimize the operation of thermal engines in general and of gas turbines in particular. This requires accurate knowledge of their performance. In the case of turbomachines, performance is usually estimated by assuming an adiabatic flow. This assumption is inappropriate, however, for small-scale machines such as turbochargers and micro gas turbines. This study presents the influence of heat transfer on their performance. The concept of entropic temperature is developed and a general exergy analysis conducted in order to quantify accurately the available energy dissipation. Both a turbocharger and a gas turbine with internal heat transfer are investigated. Under the adiabatic assumption, the model results are overestimated. New gas turbine maps have therefore been generated and new operating points defined. The trends of the modeling results thus obtained are compared with the performance measured on a micro gas turbine with and without insulation. Fuel consumption is higher with internal heat transfer.

Tribological Characterization of Machining at Very Small Contact Areas

When machining miniaturized components, the contact conditions between the tool and the workpiece exhibit very small contact areas that are on the order of 10−5 mm2. Under these conditions, extremely high contact stresses are generated, and it is not clear whether macroscopic theories for the chip formation, cutting forces, and friction mechanisms are applicable. For this reason, the present investigation has focused on creating a basic understanding of the frictional behavior in very small scale machining processes so that evaluations of standard macroscale models could be performed. Specialized machining experiments were conducted on 70/30 brass materials using high-speed steel tools over a range of speeds, feeds, depths of cut, and tool rake angles. At each operating condition studied, the friction coefficient and the shear factor τk were obtained. Based on the experimental results, it was determined that the standard macroscopic theory for analyzing detailed friction mechanisms was insufficient in very small scale machining processes. An approach that utilized the shear factor, in contrast, was found to be better for decoupling the physical phenomena involved. Utilizing the shear factor as an analysis parameter, the parameters that significantly influence the friction in microscale machining processes were ascertained and discussed.

The 9th international symposium on fluid control, measurement and visualization (FLUCOME 2007)

This paper is the report on the Ninth International Symposium on Fluid Control, Measurement and Visualization. The symposium was scheduled on September 17-19, 2007 in Florida State University Center, Tallahassee Florida, USA. Topics for FLUCOME 2007 included fluid processes across a wide range of scales in multiple disciplines: from micro-scale fluid flows in micro biomechanical devices, small-scale machine flows to large-scale civil and environmental fluid flows, and global scale geophysical and meteorological fluid flows.

Torque and Twist against Superlubricity

Superlubricity between incommensurate surfaces provides a desired low-friction state essential for the function of small-scale machines. Here we demonstrate experimentally and theoretically that superlubricity in contacts lubricated by lamellar solids might be eliminated due to torque-induced reorientation coupled to lateral motion. We find that the possibility of reorientation always leads to stabilization of a high frictional state which corresponds to a commensurate configuration.

Micro-fabrication of a prototype hybrid GaAs/ceramics cantilever for SPM applications

As a first step to realize new type cantilevers to be used in the scanning probe microscopies (SPMs) more suitable to optical and magnetic nano-scale analyses, we have fabricated a prototype hybrid GaAs/ceramics cantilever composed of a tip, a beam, and a small seat made of GaAs, and a large seat made of ceramics. We have established the fabrication process for this hybrid GaAs/ceramics cantilever and succeeded in obtaining preliminary atomic force microscopy (AFM) and magnetic force microscopy (MFM) images. The GaAs components were made by wet etching with phosphoric acid for the tip and sulfuric acid for the beam and small seat, while the large ceramic pedestal was made with small-scale machine fabrication technologies. The tips, with ∼6 μm height, 30 nm top curvature, and a high aspect ratio, were fabricated reproducibly. Beam length and thickness of the fabricated cantilevers were within 168–479 and 7.5–20 μm, respectively. The measured resonance frequencies of 30–365 kHz agreed well with the calculation. Since GaAs has a smaller Young's modulus than Si and a variety of unique optic and magnetic properties which cannot be realized in Si, the fabrication technologies developed here could contribute to the production of a low-cost GaAs cantilever possibly used in new type scanning estimation measurements.

An examination of economic efficiency of Russian crop production in the reform period

AbstractThis article examines economic efficiency (EE) of crop production of Russian corporate farms for 1993–1998. EE declined over the period, due to declines in both technical and allocative efficiency. Technical efficiency (TE) results indicate that output levels could have been maintained while reducing overall input use by an average of 29–31% in 1998, depending on the method used, while the allocative efficiency (AE) results show that costs could have been reduced about 30%. The EE scores show that Russian corporate farms could have increased efficiency by reducing the use of all inputs, particularly fertilizer and fuel. Russian agriculture inherited machinery‐intensive technology from the Soviet era, which may be inappropriate given the relative abundance of labor in the post‐reform environment. Investment constraints have prevented the replacement of old machinery‐intensive technology with smaller scale machines that allow for a more labor‐using technology.

Design and Analysis of a Spherical Continuously Variable Transmission

In this article we propose the design of a novel continuously variable transmission, the spherical continuously variable transmission (S-CVT). The S-CVT consists of a sphere, input and output discs, and variators. The rotating input and output discs are connected to the power source and output shafts, respectively, while the sphere is situated between the input and output discs. The transmission ratio is controlled by adjusting the location of the contact point between the variators and the sphere, which in turn controls the axis of rotation of the sphere. The S-CVT can smoothly transit between the forward, neutral, and reverse states without any brakes or clutches, and its compact and simple design and its relatively simple control make it particularly effective for mechanical systems in which excessively large torques are not required (e.g., mobile robots, household appliances, small-scale machining centers). We describe the operating principles behind the S-CVT, including a kinematic and dynamic analysis. Simulations and experiments with a constructed prototype are conducted to assess the performance of the S-CVT, including a study of its energy efficiency vis-a´-vis reduction gears.

Lneuro 1.0: a piece of hardware LEGO for building neural network systems

Neural network simulations on a parallel architecture are reported. The architecture is scalable and flexible enough to be useful for simulating various kinds of networks and paradigms. The computing device is based on an existing coarse-grain parallel framework (INMOS transputers), improved with finer-grain parallel abilities through VLSI chips, and is called the Lneuro 1.0 (for LEP neuromimetic) circuit. The modular architecture of the circuit makes it possible to build various kinds of boards to match the expected range of applications or to increase the power of the system by adding more hardware. The resulting machine remains reconfigurable to accommodate a specific problem to some extent. A small-scale machine has been realized using 16 Lneuros, to experimentally test the behavior of this architecture. Results are presented on an integer version of Kohonen feature maps. The speedup factor increases regularly with the number of clusters involved (to a factor of 80). Some ways to improve this family of neural network simulation machines are also investigated.

Non-Newtonian and Non-Isothermal Modeling of 3D-Flow in an Internal Mixer

Abstract In previous work we have applied hydrodynamic lubrication theory to simulate 3-dimensional flow of a polymer melt or elastomer in an internal mixer. That study presumed isothermal Newtonian flow in a flattened out mixing chamber. In the present paper, we take into consideration both non-Newtonian flow properties of the melt/elastomers and increase in temperature due to viscous dissipation heating. We consider the influence of non-Newtonian viscosity on flow patterns in the internal mixer. Viscous dissipation heating in the internal mixer is also modelled. It is shown that large scale internal mixers tend to operate adiabatically while small scale machines are close to isothermal. Temperature-time profiles are predicted for laboratory and large scale internal mixers.

Electrical tests on a fully superconducting synchronous machine

The emergence of ultrafine multifilamentary superconducting wires with very low losses under varying magnetic fields allowed the testing in 1987 of a three-phase 50-Hz superconducting stationary winding with a classical copper/iron rotor. A superconducting field rotor was constructed and mounted into the previous stator to form a fully superconducting machine. The rotating part is rather simple: a helium vessel rotates into a low-pressure vessel to avoid thermal losses by turbulence. There is no thermal shielding due to the cryogenic environment of the stator, and the electromagnetic shield, present in classical superconducting generators, has been avoided with the low loss superconductors used. The combined 900-mm-long, 320-mm-diameter, rotor-stator cryostat uses fiberglass composites in the central parts due to the rotating fields under permanent or transient operations. The first electrical tests of this small-scale 18-kVA machine under permanent and sudden-short-circuit tests are reported.

Evaluation of functions on microcomputers: ln ( X)

This paper is a continuation of a study of numerical software for evaluating elementary functions in a microcomputer environment. In this note we describe polynomial and rational polynomial approximation-type algorithms for evaluation of the natural logarithm. Focus is on the design of fast algorithms that preserve full machine precision in small scale machines which use truncated binary fixed point arithmetic with at most a sixteen-bit wordlength. Included in this paper are the results of the performance of these algorithms on simulated eight- and sixteen-bit microcomputers.