Recently micro cutting has been applied to manufacturing of micro devices. Burr formation is a troublesome problem in micro cutting. From the point of view of the required accuracy, burr removal in the micro manufacturing cannot be performed by the manual operations or the additional cuttings. The paper presents a deburring process to remove the burrs on the micro-scale structured surfaces, which are machined in micro milling. In order to remove the burrs on the pillars in the structures, the study examines burr removal milling, polishing and water jet finishing. Burr removal milling leaves the cutter traces with adhesion of the chips on the pillars. Polishing finishes the surfaces with removing the burrs on the top of the pillars. A supporting device is used for protecting the edge shapes of the pillars in polishing. Then, the burrs on the side of the pillars can be removed in water jet finishing. A water jet machine driven by a low pressure pump is developed to remove the burrs without losing their shapes. The process sequence of polishing and water jet finishing is effective in removing the burrs in micro milling. The presented process is discussed to manufacture the micro-scale structures in mechanical manner based on the axiomatic design.

Fabrication of microelectrodes with different shape has become so important due to the high demand of industrial products not only with diversified shape but also of reduced dimension. However, to date, fabrication of different shapes in single setup is not possible and also need special indexing attachment. To solve this problem, in this study, a specially designed block containing three V slot of 60° 90° 120° has been designed and fabricated using wire cut machine to facilitate the fabrication of different shape micro-electrode. Then, with the help of block electro discharge machining method using this specially designed block, the feasibility of fabrication of microelectrodes with symmetrical and non-symmetrical section e.g. conical tool of angle 60° 90° 120°, rectangular, triangular, circular and semicircular tool from commercially available polycrystalline diamond rod has been investigated. As the size of electrode is of micron scale, multi-pass machining strategy has been taken to reduce the volumetric material removal, and thus to diminish the possible electrode breakage, which is especially significant. Finally, this strategy of using specially designed block has been found to be feasible for producing microelectrodes of various symmetrical and non-symmetrical sections down to few microns. In addition to this, the capabilities of these fabricated tools have been depicted by recommending few applications on both conductive and nonconductive material.

Many experiments on rotary ultrasonic machining (RUM) have been conducted to study how input variables (including tool rotation speed, ultrasonic power, feedrate, and abrasive size) affect output variables (such as cutting force, torque, surface roughness, and edge chipping) by using diamond tools. However, a literature review has revealed that there is no reported study on CBN tools in RUM. This paper, for the first time in literature, presents an investigation of RUM of stainless steel using CBN tools. Firstly, an introduction of superabrasive materials and RUM principle was provided. After presenting the experiment procedures and workpiece properties, it reports the results on tool wear, cutting force, torque, surface roughness in RUM of stainless. Finally, it discusses and compares the performances of diamond and CBN tools in RUM of stainless steel under certain conditions.

Cellulosic biomass is an important source for making biofuels. However, there are several barriers to cost-effective manufacturing of biofuels using cellulosic biomass. One such barrier is related to the high transportation cost due to the low density of cellulosic biomass. Pelleting of cellulosic biomass is one way to increase its density. This paper reports an experimental study on ultrasonic vibration-assisted pelleting of cellulosic biomass. The study was focused on the effects of moisture content (MC) on pellet density of three kinds of cellulosic biomass (wheat straw, switchgrass, and sorghum). The experimental results show that sorghum has the highest density with three levels of MC among these biomass materials. The highest density was found with sorghum of 20% MC.

Cellulosic biofuels can be used to replace traditional liquid transportation fuels. Cellulosic biomass is feedstock in manufacturing of cellulosic biofuels. However, the low density of cellulosic biomass feedstock hinders large-scale and cost-effective manufacturing of cellulosic biofuels. Another bottleneck factor in manufacturing of cellulosic biofuels is the low efficiency of the enzymatic hydrolysis of cellulosic biomass materials resulting in a low sugar yield. Ultrasonic vibration-assisted (UV-A) pelleting can increase the density of cellulosic biomass feedstocks via combined effects of mechanical compression and ultrasonic vibration of the tool on the cellulosic biomass. Meanwhile ultrasonic vibration may act as a beneficial pretreatment for enzymatic hydrolysis, which can possibly increase the efficiency of hydrolysis and obtain a higher sugar yield. The pressure and the ultrasonic power are important parameters in UV-A pelleting. Their effects on pellet quality (density, durability, and stability) and sugar yield (after hydrolysis) are experimentally investigated.

Accurate and precise micro tools are essential for the micromachining of highly complex features in a wide variety of engineering materials including metals and ceramics. Simple shapes like cylindrical rods with micrometer level dimensions are increasingly being used as micro tools in processes such as micro ultrasonic machining. High aspect ratio tools are necessary to produce deep micro holes and other high aspect ratio structures. Micro tools produced by the well known wire electro-discharge grinding suffer from deformation due to the thermal stresses. Therefore, alternate micro tool manufacturing techniques are being explored actively. In this paper, the manufacturing of micro tools by micro electrochemical machining (ECM) is discussed. The micro tools are made under different experimental conditions using an in-house built micro electrochemical machining system and analyzed for tool tip radii and cone angles. Further, the feasibility of extremely high aspect ratio micro tools is studied. Using micro ECM, micro tools having mean diameters of 10 microns with tips as small as 50 nm and aspect ratios of the order of 300 are achieved.

Increasing demands and concerns for the reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic biofuels. However, several technical barriers have hindered large-scale, cost-effective manufacturing of cellulosic biofuels, such as the low density of cellulosic feedstocks (causing high transportation and storage costs) and the low efficiency of enzymatic hydrolysis process (causing longer processing time and low sugar yield). Ultrasonic vibration-assisted (UV-A) pelleting can increase the density of cellulosic materials by compressing them into pellets. UV-A pelleting can also increase the sugar yield of cellulosic biomass materials in hydrolysis. At present, the effects of process variables in UV-A pelleting on pellet quality (density, durability, and stability) and sugar yield have not been adequately investigated. This paper reports an experimental investigation on UV-A pelleting of wheat straw. A 2 4 factorial design is employed to evaluate the effects of process variables (moisture content, particle size, pelleting pressure, and ultrasonic power) on output variables (pellet density, durability, stability, and sugar yield).

Edge chipping is an important quality parameter in ultrasonic-vibration-assisted grinding (UVAG) of advanced ceramics. In this paper, the effects of cutting tool design, including three different tool angles at tool end surface and wall thickness of the cutting tool (core drills), and process variables on edge-chipping are investigated using a finite element analysis (FEA) model. Experiments are also conducted to verify the FEA predicted effects of process variables on edge-chipping for the three cutting tools.

The Makyoh, or “magic mirror,” is a bronze mirror originating from ancient Japan. The mirror reflects an image on a distant wall when parallel light such as sunlight shines on it. Craftsmen with a great amount of cumulative experience and intuition have produced the Makyoh, and the skill of these craftsmen has advanced continuously. However, there are very few craftsmen today who can make Makyoh mirrors. The problem of the diminishing number of craftsmen, which is not confined to creating the Makyoh, has drawn considerable attention. There have been attempts to digitize the skills (or inferred knowledge) of these craftsmen. To maintain traditions into the future, it is important to assist producers with traditional craftsmanship who have long supported Japanese industry. Therefore, the digital manufacturing of a Makyoh using numerically controlled machining and polishing was attempted. In our first report, a new method to make the Makyoh using a machining center was demonstrated [1]–[3]. In the present report, the influence of the topography of a Makyoh surface was examined, produced by the line machining method, on the projected image. As a result, (1) with our method it was possible to make the makyoh using all three materials. (2) The difference in contrast between cutting on the outer side and on the inner side was large with a decreasing radius of curvature R in circular cutting. (3) We succeeded in processing complicated shapes by using straight lines and curved lines.

Ultraprecision machining of hardened steel by the conventional cutting (CC) technique using diamond tools is impossible because of highly chemical affinity between carbon and iron at higher temperature during machining. An intermittently cutting technique, namely, ultrasonic elliptical vibration cutting (UEVC) technique has been being applied for high-quality machining of various difficult-to-cut materials for the last decade. However, study on machining of hardened stainless steel using polycrystalline diamond (PCD) tools applying this cutting technique has not been reported yet. This study presents an experimental study on UEVC of hardened stainless steel (a typical Stavax of 49 HRC) using PCD tools. Face cutting experiments have been carried out to investigate the effects of conventional machining parameters: depth of cut, feed rate, and spindle rotational speed on the performance parameters such as cutting force, tool flank wear, surface roughness and chip formation. A minimum surface roughness R a value of 10 nm, measured by a stylus profilometer, was achieved. It can be concluded that, while applying UEVC technique, the inexpensive PCD tools compared to the single crystal diamond tools can be effectively applied to obtain optical surface for producing precise dies and molds from hardened steel.

There is a lack in understanding of the frictional contact condition during friction stir processes. High temperature, force and work material adhesion to and from the tool make the coefficient of friction difficult to measure. In this study, an experiment was set up to simultaneously measure the temperature and normal and frictional forces between a rotating tool and a stationary workpiece at steady state conditions. The coefficient of friction was measured for increasing temperature. A simple model was created to convert the thermocouple temperature measurement to the temperature at the point of contact between the tool and workpiece. It was found that the coefficient of friction had a decreasing trend as temperature approached the solidus temperature of the work material. The results and analysis of the experiments are presented.

An alternating magnetic field assisted finishing (MAF) technique has been developed to finish the 5–20 μ m wide pore sidewalls of micro-pore X-ray focusing optics fabricated using micro-electro-mechanical systems (MEMS) techniques. To understand the material removal mechanism, this MAF technique is used to finish a silicon MEMS micro-pore X-ray optic that had previously undergone a hydrogen annealing treatment. Compared to the unfinished surface, distinctive surface features are observed on the finished surfaces using scanning electron microscopy, optical profilometry, and atomic force microscopy. This demonstrates the finishing characteristics and reveals the material removal mechanism on the nanometer scale. Moreover, the representative unfinished and finished micro-pore sidewall surfaces show a reduction in roughness due to finishing from 1.72 to 0.18 nm Rq .

Thin films have been finding more and more applications in electronics, optical devices, and energy conversion and storage devices, to name a few. As one of the most promising thin film deposition techniques, air atomizing spray pyrolysis, which uses compressed air to disrupt the liquid stream into droplets, has been favored in scientific and engineering communities. However, the effects of operating conditions such as liquid flow rate, atomizing air pressure, fan air pressure, and air gap on the geometric properties of deposited thin film are still not systematically studied. The objective of this study is to experimentally investigate the effects of air spraying operating conditions on the surface roughness and thickness of deposited zinc oxide (ZnO) thin film. It is found 1) The surface roughness increases with the liquid flow rate, but decreases with the atomizing air pressure, fan air pressure, and air gap; 2) The surface roughness decreases along both the X and Y directions under any given operating condition; 3) The thickness increases with the liquid flow rate and the atomizing air pressure, but decreases with the fan air pressure and the air gap; and 4) The thickness generally changes differently along the X and Y directions. Along the X direction, it decreases monotonically; however, along the Y direction, it increases first then decreases as in a saddle shape. While ZnO film deposition is studied, it is expected that the above conclusions may be applicable in air spraying other materials.

Cryogenic treatment is a heat treatment process in which the specimen is subjected to an extremely low temperature of the order of −300° F and below, to cause beneficial changes in the material properties. The advantages of cryogenic treatment include relieved residual stresses, and better electrical properties. Electro discharge machining (EDM) is a well known nontraditional machining process in which electrical energy is converted to thermal energy to remove material by melting and evaporation from electrically conductive materials. The process performance of EDM is affected by several factors including the material properties. In this study, the effect of cryogenic treatment on the performance of EDM is investigated experimentally. Copper tool electrodes were subjected to two different treatment methods, namely cold treatment (around −150° F) and deep cryogenic treatment (around −300° F). Using these electrodes, experiments were conducted to study the effect of various process parameters. Significant improvement in material removal rate was observed for EDM with cryogenically treated tools. However, their effect on tool wear is only marginal.

A study was undertaken to determine the feasibility of the AWJ process for controlled depth milling of gamma Titanium Aluminide tiles. It was demonstrated that milling can be accomplished to 0.025-mm accuracy. To overcome undercutting near rib roots, the jet was clock-angled at about 15 degrees to the vertical every set of passes. This allowed the milling to thin skins of about 0.5-mm. It was observed that as the material is milled, stresses were relieved and either deformation or cracking may result. Accordingly parts need to be annealed before milling. The milling to thin skins was successfully demonstrated on 150mm × 300-mm parts without adverse effects. Also, the process of milling of dual rib height was developed using dual mask approach. Abrasive particle embedding on the milled surfaces was observed to be about 0.15% of the area, but cleaning with plain waterjets showed that all embedded particles can be removed. A detailed economic analysis confirmed that the AWJ milling process is relatively inexpensive and highly productive. The complete cost of milling including mask cutting, overhead, capital, and running cost is less than $300/ft2.

Laminated tooling where parts are manufactured layer by layer is a promising technology. It can help to reduce production costs and make complex tools with conformed cooling channels. Laminated tooling is based on taking sheets of metal and laser cutting profiles on them before stacking them to produce the final product. If the sheets are thin, the surface quality of final product will be good; however the cost of laser cut is increased in this case. Therefore, finding the optimum set of layers thicknesses to have the minimum surface jaggedness and the number of slices at the same is the aim of this research. A modified version of Genetic Algorithm is used for optimization purpose.

Diamond grinding wheels are important tools to carry out precise or ultra-precise grinding of difficult-to-machine materials; however, the difficulty of dressing diamond grinding wheels is a bottleneck problem in their wide application. The objective of this study is to identify the feasibility of near-dry electrical discharge dressing (EDD) of metal bonded diamond grinding wheels. Through design of experiment (DoE), sets of tests were carried out to select proper dielectric mist composition and electrode material, to quantify the dielectric mist composition, to choose the electrode shape and rotating speed, and to investigate the influence of electric discharge parameters on dressing performance. By applying optimized experimental parameters to near-dry EDD of metal bonded diamond grinding wheels, more diamond grits protruded out of the grinding wheel surface, and the worn diamond grinding wheel got sharpened.

In this paper an effort is made towards improving the performance of MRAFF process by providing a rotating magnetic field externally to the polishing medium by using permanent magnets in addition to the reciprocating motion provided to the polishing medium by a hydraulic unit. This finishing process creates a smooth mirror like finished surface with a few directional cutting marks (i.e. hatch pattern like honing) on the finished surface of stainless steel, brass, and EN-8 workpieces. Preliminary experimental study is conducted on MRAFF and rotational (R)-MRAFF processes to compare their process performance in terms of change in Ra (ΔR a ) and change in material removal (ΔMR). Later complete experimental study of R-MRAFF process is carried out using central composite rotatable design (CCRD) and the responses are plotted using response surface methodology (RSM). Optimum finishing conditions are identified by optimization method developed by Derringer and Suich using Design-Expert ® software. The present study shows that rotational speed of the magnet has significant effect on output response (%ΔR a ). The finished surfaces are characterized in detail by atomic force micrographs (AFM), and scanning electron micrographs (SEM) to analyze the changes in surface generation at different RPM.

Fiber reinforced composite materials are now frequently being used over conventional materials for their ability to achieve tailored properties and performance characteristics. With the recent advancements in manufacturing techniques, short-fiber composites are coming into prominence in this sector, with their cost advantage and their capability for large throughput. Randomness of fiber orientation is inherent to short fiber composite manufacturing processes. In order to effectively manipulate the mechanical properties of a short-fiber reinforced composite, it is imperative to adequately control the orientation of the fibers during the deposition stage. A process is currently developed to acquire geometrical data of the target object and to utilize it to create a short-fiber reinforced component with controlled fiber orientation. The topological data acquisition of the object is made possible using non-contact 3D imaging techniques. The geometric data is then transferred to a commercial CAD package for the added capability to manipulate the geometry as may be required for specific applications. Subsequently, geometric data constitutes the basis of path planning for the tooling processes. In our process, a novel rapidly re-configurable tooling and molding technology is employed by which a 6-axis robotic arm is used to sculpt a pin-device vacuum surface. After the tooling is completed, the robotic arm will use a deposition nozzle to orient a steady stream of initially random short-fiber from a feeder into a unidirectional output, onto the tool surface. By controlling the position and orientation of the deposition nozzle, it is possible to control the orientation and density of fiber in each section of the near-net shaped composite pre-form. The fiber pre-form is then impregnated with a suitable matrix medium and cured to create the required component. The outlined process is thus capable of manufacturing a near-net shaped short-fiber reinforced component with highly specific mechanical properties. One of the many applications envisaged using this process is the manufacture of custom form-fitting braces, masks and guards for use in healthcare products. A patient intervention can have his or her features acquired using stereo-imaging and have corrective measures incorporated into the device prior to manufacturing. By controlling the orientation and density of the fiber at different portions of the device, it is possible to provide adequate support at specific areas or to restrict movement in specific directions while providing compliance to movement in the others.

Magnetorheological finishing (MRF) process is one of the fine abrasive finishing processes used to get better surface finish on a semi finished part. The present work is aimed at investigating the effectiveness and validity of magnetorheological finishing process and finding out the process parameters (such as finishing time, rotational speed of carrier wheel, abrasive concentration, and working gap) and their effectiveness on surface finish characteristics. MRF process is applied on brass and nonmagnetic stainless steel workpieces which were initially finished by the grinding process. The results of experiments were statistically analyzed by response surface methodology (RSM) to form an empirical model for the responses generated during the process. Also, an attempt has been made to model and simulate the finishing operation in MRF process. Apart from this, the micro structure of the mixture of magnetic and abrasive particles in magnetorheological polishing fluid (MR Fluid) has been proposed. Thereafter the normal force on the abrasive particles is calculated from the applied magnetic field and a model for the prediction of surface roughness has also been presented. Finally, theoretical results calculated using the proposed model, have been compared with the experimental results to validate the model developed.