Chip Volume Research Articles

Molecular Dynamics Simulation Study of Mechanical Effects of Lubrication on a Nanoscale Contact Process

Using molecular dynamics simulation, we study the effect of a lubricant on indentation and scratching of a Fe surface. By comparing a dry reference case with two lubricated contacts—differing in the adsorption strength of the lubricant—the effects of the lubricant can be identified. We find that after an initial phase, in which the lubricant is squeezed out of the contact zone, the contact between the indenter and the substrate is essentially dry. The number of lubricant molecules confined in the tip-substrate gap increases with the lubricant adsorption energy. Trapped lubricant broadens the tip area active in the scratching process—mainly on the flanks of the groove—compared to a dry reference case. This leads to a slight increase in chip height and volume, and also contributes to the scratching forces.

Engineering Texture Properties of Instant Controlled Pressure Drop (DIC) Dried Carrot Chips via Modulating Osmotic Conditions

Instant controlled pressure drop (DIC) as a novel drying method can significantly expand the volume of fruit and vegetable chips, resulting in a desirable texture and crispy mouthfeel. Osmotic pretreatment (OP) is an effective processing unit used before DIC to improve the overall qualities of final products. However, the effects of OP on the texture of DIC-dried fruits and vegetables are not fully understood. Thereof, the effects of osmotic treatments on the volume, texture, microstructure, color, and sensory qualities of DIC-dried carrot chips were investigated. The results confirmed that the expanded volume of the DIC-dried samples was highly dependent on solute gain (R2 = 0.9573). According to X-ray microtomographic analysis, the microstructural characteristics of the samples were substantially affected by OP conditions, and the distribution range of pore size was broadened with increasing of osmotic time, while the homogeneity of wall thickness increased with decreasing of osmotic time. Furthermore, sensory evaluation showed that the samples appropriately pretreated (e.g., 60 °Bx for 4 or 6 min) were of great overall quality, and the indicators included hardness, volume, and color, which were significantly correlated with the solute gain (p < 0.01). Overall, the controlled osmotic processing could be used as an excellent pretreatment for modulating the volume expansion and microstructure of DIC-dried carrot chips, thus premeditating the engineering of the texture properties.

The description of oil absorption behavior of potato chips during the frying

The oil absorption during frying is a complex phenomenon and how the oil permeated into the sample is still not clear. The oil absorption behavior of potato chips was investigated by combined the dyed oil methods, digital photo analysis, confocal laser scanning microscopy, low field nuclear magnetic resonance imager and mercury porosimeter. The relationship between the oil absorption with frying time, microstructure and pore formation was discussed. The results showed that the content of total oil and structural oil of potato chips increased with the increasing of frying time, and it reached 40.44% and 6.44% at 2 min, respectively. Penetrated surface oil reached the maximum at 2 min and then decreased. The oil infiltration was in accordance with the sequence from outside to inside of potato chips and the oil was distributed along the contours of the cells and filling cell interstitial. The oil absorption was closely related to the pore properties, and the total pore volume and porosity of potato chips increased but bulk density decreased during the first 8 min, which remained constant at 1.63 mL g−1, 0.42 g mL−1 and 68.7% during 8–12 min. The results could provide scientific guidance for the production of low-fat and healthy fried food.

Molecular dynamics simulation of subsurface damage mechanism during nanoscratching of single crystal silicon

Three-dimension molecular dynamics (MD) simulation is employed to investigate the nanoscratching process of monocrystalline silicon with diamond tools. The effects of tool geometry on subsurface damage and scratching surface integrity are investigated by analyzing phase transformation, chip, defect atoms, hydrostatic stress, von Mises stress and workpiece deformation. In addition, a theoretical analytical model to study the subsurface damage mechanism by analyzing the zone size of phase transformation and normal force with diamond tools at different half-apex angles on silicon surfaces is established. The results show that a bigger half apex angle causes a higher hydrostatic stress, a larger chip volume, a higher temperature and a higher potential energy, and increases subsurface damage. The results also reveal that the evolution of crystalline phases is consistent with the distribution of hydrostatic stress and temperature. In addition, tip scratching with a bigger half-apex angle would result in a larger scratching force and a bigger phase transformation zone, which is in good agreement with the results of the theoretical analytical model.

Comparative study on machinability improvement in hard turning using coated and uncoated carbide inserts: part II modeling, multi-response optimization, tool life, and economic aspects

The present study focused on mathematical modeling, multi response optimization, tool life, and economical analysis in finish hard turning of AISI D2 steel ((55 ± 1) HRC) using CVD-coated carbide (TiN/TiCN/Al2O3) and uncoated carbide inserts under dry environmental conditions. Regression methodology and the grey relational approach were implemented for modeling and multi-response optimization, respectively. Comparative economic statistics were carried out for both inserts, and the adequacy of the correlation model was verified. The experimental and predicted values for all responses were very close to each other, implying the significance of the model and indicating that the correlation coefficients were close to unity. The optimal parametric combinations for Al2O3 coated carbide were d1–f1–v2 (depth of cut = 0.1 mm, feed = 0.04 mm/r and cutting speed = 108 m/min), and those for the uncoated tool were d1–(0.1 mm)–f1 (0.04 mm/r)–v1 (63 m/min). The observed tool life for the coated carbide insert was 15 times higher than that for the uncoated carbide insert, considering flank wear criteria of 0.3 mm. The chip volume after machining for the coated carbide insert was 26.14 times higher than that of the uncoated carbide insert and could be better utilized for higher material removal rate. Abrasion, diffusion, notching, chipping, and built-up edge have been observed to be the principal wear mechanisms for tool life estimation. Use of the coated carbide tool reduced machining costs by about 3.55 times compared to the use of the uncoated carbide insert, and provided economic benefits in hard turning.

An FPGA-based controller for a 77 GHz MEMS tri-mode automotive radar

This paper presents a Xilinx Virtex 5 FPGA platform based signal processing algorithm that was designed, implemented and experimentally verified for use in a MEMS based tri-mode 77 GHz FMCW automotive radar to determine range and velocity of targets in the vicinity of a host vehicle. It provides short (SRR), medium (MRR), and long-range radar (LRR) coverage using a single FPGA. The MEMS radar comprises of MEMS SP3T RF switches, microfabricated Rotman lens and a microstrip antenna embedded with MEMS SPST switches, in addition to other microelectronic components. A CA-CFAR module has been used to eliminate false targets in a multi-target clutter affected scenario. The developed algorithm enables the MEMS radar to detect 6 targets in a time span of 6.1 ms between a distance of 20–170 m with range resolutions of 0.07, 0.11 and 0.19 m respectively for SRR, MRR and LRR. A maximum relative velocity of 300 km/h can be determined with a velocity resolution of 6.84 km/h. The refresh rate is 2.048 ms for each mode of radar which is nearly 40 times lower than the commercially available BOSCH LRR3 radar. The developed FPGA based radar signal processing algorithm can be implemented in an ASIC which can be batch fabricated to lower the production cost for high chip volumes. This will enable automotive radars to become a standard item for all the vehicles on the road.

PERUBAHAN MASSA AIR, VOLUME, DAN UJI ORGANOLEPTIK KERIPIK BUAH DENGAN BERBAGAI VARIASI WAKTUPADA PENGGORENGAN TEKANAN HAMPA UDARA

The processing of fruits by frying are interesting to be developed. One of the potential fruit processed and fruit chips are developed papaya (Carica papaya L.). This study aimed to determine changes in water content and volume of papaya chips during frying, and test results hedonic papaya chips. The study was conducted by using the experimental method completely randomized design (CRD) with observation every 15 minutes, for 90 minutes during frying using vacuum fryer. Observations moisture content, volume, and the level of preference (hedonic), performed before and after frying. Analysis of the data by analysis of variance (ANOVA) followed by Tukkey test at 5%. The results showed that the decrease in water content and volume reduction papaya chips tend to stop in a frying for 60 minutes. To test hedonic color and flavor, crispy papaya highly preferred is frying for 60 minutes. As for the hedonic test on the texture, chips are the most preferred frying for 90 minutes

Geometrical Simulation of Chip Production Rate in Micro-EndMilling

In conventional-scale machining, the mechanics of the tool-workpiece interface are dominated by shearing. But, in micro-machining, the mechanics of the tool-workpiece interface are affected also by ploughing and elasto-plastic workpiece deformation, due to the minimum chip thickness effect as the minimum chip thickness becomes comparable to the uncut chip thickness. Especially, the ploughing effect increases cutting forces resulting in poor surface integrity and burr formation. A clear understanding of the relationships between shearing, ploughing, and elasto-plastic deformation is required to manage these effects. Here, we propose that the chip production rate is an indicator of the state of the interaction at the tool-workpiece interface. In this paper, the influence of the minimum chip thickness effect is investigated by a geometrical simulation of the chip production rate due to the varying uncut chip thickness, less than or above the minimum chip thickness in micro-endmilling. The chip production rate is predicted by counting the number of chips generated by the intermittent engagement of the cutting tooth based on the trochoidal path. The simulation results predict as much as 50% reduction and 200% increase in the chip production rate at a certain chip volume range as the uncut chip thickness becomes smaller than minimum chip thickness assuming that the cutting edge radius is constant.

Effects of the mass and volume shrinkage of ground chip and pellet particles on drying rates

The effects of varying the mass and volume of ground chip and pellet particles on the particle drying rate were analyzed. Samples of whole pellets and chips were hammer milled using a 3.2mm screen and the ground chip and pellet particles were found to have similar size distributions, although the pellet particles were denser and more spherical than the chip particles. Prior to drying, water was added to the particles to obtain 0.10, 0.30, 0.50, 0.70, and 0.90 moisture contents (on a dry mass basis). The moistened particles were subsequently dried in a constant temperature thin layer dryer set at 50, 100, 150, or 200°C under dry pure nitrogen, dry compressed air, or atmospheric air. The chip and pellet particles exhibited similar degrees of shrinkage, but the pellet particles underwent a greater reduction in their bulk volume during drying. It appears that the more spherical pellet particles are prone to shrinkage in more than one direction, whereas the needle-like chip particle shrink only in one direction. A variable radius first order drying model was found to fit the experimental data better than a fixed radius model.

Study on Analysis of Cutting Mechanism of Ball End Mill for Concave and Convex Spherical Surface Using 3D-CAD

In this paper, cutting mechanism and cutting performance of ball end mill for spherical surface with contour path method is investigated. Ball end mills are used to produce molds, dies and so on. However, the edge shape is complex, so cutting process is not clear. Then, it is not clear effectively using method of the tool based on good cutting performance. Therefore, in this study, the purpose is proposal of high efficient and high accurate cutting method is using 5-axis control machine tool. At first, cutting model assembled by a ball end mill (R8 mm) and a workpiece with convex or concave spherical surface (Workpiece radius 20 mm) is carried out using 3D-CAD (SolidWorks). The pick feed direction which is from bottom to top is defined “Stepped up”, the one which is inverse direction is defined “Stepped down”. In addition, both cutting methods include up milling and down milling, then there are four cutting modes. The radius of tool path for contour path are varied from 14.0 mm to 19.4 mm for convex spherical surface, from 6.5 to 9.2 mm for concave spherical surface. The lead angle of the tool is defined the plus sign when the tool is inclined to the tool feed direction and varied from-45° to 45°. Secondly, the cutting cross-sectional area is calculated by the interference of a rake surface of the tool and an uncut chip volume which can be removed by one cutting operation. Thirdly, cutting experiments are done in order to measure cutting force. Finally, analytical and experimental results are discussed, and then the cutting conditions which are expected good cutting performance are considered.

Numerical simulation of chip ploughing volume in micro ball-end mill machining

Chip ploughing becomes a more serious problem in micro-machining due to its relatively large size with respect to the finished part, negatively impacting on the accuracy of the finished surface. In this work, a 3D geometry model of the chips generated during micro ball-end milling is introduced to accurately calculate the chip ploughing volume to support needed tool path adjustments for ensured accuracy of the finished part. A new method is developed to compute the chip ploughing volume by dividing the modeled chip into many discrete pieces over a ploughing dominated region and a shearing dominated region. Two simulation methods for calculating the chip volume for two example tool paths are presented. Different axial depths of cut, spindle speed and feed rate are tested to study the ploughing mechanism and reduce the ploughing effects. Experiments of cutting force measurement are used to compare with the changes of the simulated ploughing and shearing volume.

The impact of log surface damage caused by harvester Eucalyptus debarking on pulp value recovery

Mechanised harvesting operations are growing in popularity in South Africa, as motor-manual and manual harvesting operations pose significant health and safety risks to workers. Potential damage inflicted by single-grip harvester feed rollers and delimbing knives on the log surface during debranching and debarking of eucalypts may affect chip size distributions during chip production. Chip size is important as it influences pulp quality and recovery in the kraft pulping process. The study investigated the influence of two mechanised debarking treatments in eucalypts (three feed roller passes and five feed roller passes along the stem surface) with feed-roller-induced log surface damage on pulp value recovery. The two mechanised treatments were compared against chips produced from manually debarked logs with no surface damage. In addition, the effect of two log drying periods (one week and two weeks) and three log classes (base, middle and top logs) on chip quality were also analysed. An economic evaluation was conducted to quantify potential recoverable pulp value losses associated with debarking treatments and log drying periods. Logs subject to manual debarking produced significantly less undesired sized chips than both three-pass and five-pass mechanically debarked logs and therefore had significantly greater pulp value recovery. Mechanically debarked logs had a projected pulp value recovery of R62, R86 and R123 less per bone dry tonne of chips produced from base, middle and top logs, respectively, when compared with manually debarked logs with no log surface damage after a one-week log drying period. Mechanically debarked logs also had a projected pulp value recovery of R77, R40 and R59 less per bone dry tonne of chips produced from base, middle and top logs, respectively, when compared with manually debarked logs with no log surface damage after a two-week log drying period. Logs dried for two weeks also produced significantly less under-sized chips than chips produced from one-week-dried logs and therefore had greater pulp value recovery. However, two-week-dried logs produced wood chips with significantly more over-thick chips than logs dried for one week. The volume of undesirable-sized chips produced during chipping increased with decreasing log size.

Bonded-cluster simulation of rock-cutting using PFC2D

The influence of hydrostatic pressure on rock-cutting based on Voronoi grain bonded-cluster model is investigated in this paper. Unconfined compressive strength and Brazilian tests are performed to calibrate the relations between micro-properties and mechanical properties of the rock sample. The influences of hydrostatic pressure, cutting velocity and cutting depth on rock-cutting are researched by particle flow code in 2 dimensions. With no hydrostatic pressure, the fractures in the upper area developed rather quickly into the rock along the horizontal direction when the cutter penetrates over 4 mm. The horizontal crack could eventually arrive at the free surface causing a large volume of fragment chips. Hydrostatic pressure could significantly influence the fracture evolution, inhibiting the formation of the long horizontal fracture. The influence of hydrostatic pressure on rock cutting becomes more and more obvious when the hydrostatic pressure is over 5 MPa. High hydrostatic pressure could inhibit the development of the fractures, increasing the energy requirements of drilling and effectively strengthening the rock. The influence of velocity on rock cutting is not obvious when the cutter penetration is less than 1 mm. However, the fracture volume presents a decreasing trend as the cutting velocity is increasing. There is an optimal cutting velocity for rock cutting, the corresponding optimal cutting velocity is 300 mm/s with high rock fragmentation efficiency. As the cutting depth increases, more and more micro-cracks are initiated around the cutter and the volume of the chipped fragmentation is increasing correspondingly. According to the simulation, it is believed that Voronoi grain-based model will contribute to a better understanding for the rock-tool interaction.

Effect of First Line Cancer Treatment on the Ovarian Reserve and Follicular Density in Girls Under the Age of 18 Years

Objective To study the impact of first-line antineoplastic treatment on ovarian reserve in young girls returning for ovarian tissue cryopreservation (OTC) in connection with a relapse. Design Retrospective case-control study. Setting University hospitals. Patient(s) Sixty-three girls under the age of 18 years who underwent OTC before (group 1: 31 patients) and after (group 2: 32 patients) their initial cancer treatment. Intervention(s) None. Main Outcome Measure(s) Follicular densities (follicles/mm 3 ) measured from an ovarian cortical biopsy before OTC. The ovarian volume (mL) of entire ovaries excised for OTC was also monitored. Result(s) There was no statistically significant difference in the mean age or follicular density between groups 1 and 2 (334 ± 476/mm 3 vs. 327 ± 756/mm 3 ). In contrast, the ovarian volume and total number of ovarian cortex chips cryopreserved were statistically significantly lower in patients who received gonadotoxic treatment before OTC (mean ± standard deviation [SD]: ovarian volume, 5.3 ± 3.1 mL vs. 2.9 ± 2.1 mL, respectively; number of cortex chips: 21.3 ± 8.1 vs. 15.2 ± 7.1, respectively). The reduction in the estimated ovarian reserve ranged from 10% to 20% in children to around 30% in adolescent girls (>10 years). Conclusion(s) Girls under the age of 10 tolerate a gonadotoxic insult better than adolescents, who may experience up to a 30% reduction in the ovarian reserve via first-line gonadotoxic treatment, which at present is considered to have little effect on the follicle pool. This information will improve counseling of young female cancer patients in deciding whether to undergo fertility preservation treatment.

An Analysis on the Volume of Wood Chips Derived from Thinning Used for Energy Production in 47 Prefectures

An Analysis on the Volume of Wood Chips Derived from Thinning Used for Energy Production in 47 Prefectures

Optimal tool orientation generation and chip volume/cutting force predictions for 5-axis CNC machining of curved surfaces using flat-end mills

ABSTRACTMachining using a flat-end mill with varying and optimal tool orientations and feed-rate is an ideal approach to reach the full potential of 5-axis CNC milling of curved surfaces. Rotating the flat-end mill with different tilt angles can produce different effective cutter curvatures at the cutter contact point (CCP), improving machining efficiency and surface quality with better cutter-workpiece curvature match, and avoiding gouging for concave surfaces. This CCP-focused approach, if combined with globally optimized CNC tool path and the optimal feed-rate determined by the constraining instant cutting force, present a systematic approach to optimize 5-axis CNC machining. However, this approach also presents significant challenges due to the complex tasks of modeling varying cutter and part surface geometry/interaction. This research is aimed at solving the stated research problem. Several new methods have been introduced for optimal tool orientation generation and for instant cutting chip volume a...

A numerical study of ultraprecision machining of monocrystalline silicon with laser nano-structured diamond tools by atomistic simulation

Three-dimension molecular dynamics (MD) simulations is employed to investigate the ultraprecision machining of single crystal silicon with structured nanoscale diamond tool fabricated by laser. The advantages and disadvantages of diamond machining using structured tools are discussed in comparison with those of using non-structured tools. The von Mises stress distribution, hydrostatic stress distribution, atomic displacement, stress, the radial distribution function, cutting forces, frictional coefficient, subsurface temperature and potential energy during the nanometric machining process are studied. A theoretical analysis model is also established to investigate the subsurface damage mechanism by analyzing the distribution of residual stress during the nanoscale machining process. The results show that a structured nanoscale tool in machining brittle material silicon causes a smaller hydrostatic stress, a less compressive normal stress σxx and σyy, a lower temperature and a smaller cutting force. However, the structured nanoscale tool machining results in smaller chip volume and more beta-silicon phase. Besides, the friction coefficient for tool with V-shape groove is smaller than those for non-structured tools and other structured nanoscale tools. This means that the tool with V-shape groove can reduce the resistance to cutting during the nanoscale machining process. In addition, the results also point out that the potential energy of subsurface atoms and the number of other atoms for pyramid-structured tool are much smaller than those of using non-structured tools and other structured nanoscale tools.

Chip volume and cutting force calculations in 5-axis CNC machining of free-form surfaces using flat-end mills

This paper presents two new methods and associated algorithms for numerically modeling chip geometry and calculating cutting force for parts with free-form surface during 5-axis CNC machining using a flat-end mill. Extending the computational geometry-based Alpha shape method that can only predict cutting chip geometry, a parallel slice local volume modeling approach has been added to predict cutting forces as well. To demonstrate the validity and capability of these new methods, simulation of the cutting and chip forming process of 5-axis CNC machining on a free-form surface has been carried out. Physical validation experiment in controlled conditions has been carried out on a 3-axis micro CNC machine with the two cutter rotation angles set to be zero. The predicted and measured cutting forces are in reasonably good agreement both in trend and magnitude. The presented chip volume and cutting force method can be used to perform cutting force estimation for generating optimal tool path and orientation during 5-axis milling. The method requires longer computational time than traditional analytical methods, but it supports the ultimate goal of chip volume modeling and calculation—accurate dynamics cutting force prediction.

Numerical investigation of the evolution of grit fracture and its impact on cutting performance in single grit grinding

The study of single grit grinding with different geometries is important for understanding the micro-cutting behavior and material removal mechanism during grinding. However, the geometry of the grit changes during the wear process. The most fatal wear form responsible for the change in geometry is grit fracture as it causes considerable material loss instantaneously. This paper presents a new method to simulate single grit grinding with the fracture wear effects incorporated. The simulation procedure consists of three phases. The grinding force is calculated in phase 1, the grit fracture wear is simulated in phase 2, and the geometry of the grit after fracture wear is updated in phase 3. The evolution of grit fracture and its impact on cutting performance are studied by recycling the simulation procedure until the grit wears out. The results obtained reveal that the fracture wear is primarily caused by the maximum tensile stress along the rake surface or inside the grit. The resultant grinding force fluctuates during the chip formation process and is controlled by the number of cutting edges and the effective area of the flank surface. It decreases rapidly at the initial wear stage and varies with the dulling and self-sharpening action induced by the fracture wear. The volume of grinding chip decreases with an increase in the number of micro-cutting edges, which may result from a decrease in the ploughing effect.

Conformal titanium nitride in a porous silicon matrix: A nanomaterial for in-chip supercapacitors

Today's supercapacitor energy storages are typically discrete devices aimed for printed boards and power applications. The development of autonomous sensor networks and wearable electronics and the miniaturization of mobile devices would benefit substantially from solutions in which the energy storage is integrated with the active device. Nanostructures based on porous silicon (PS) provide a route towards integration due to the very high inherent surface area to volume ratio and compatibility with microelectronics fabrication processes. Unfortunately, pristine PS has limited wettability and poor chemical stability in electrolytes and the high resistance of the PS matrix severely limits the power efficiency. In this work, we demonstrate that excellent wettability and electro-chemical properties in aqueous and organic electrolytes can be obtained by coating the PS matrix with an ultra-thin layer of titanium nitride by atomic layer deposition. Our approach leads to very high specific capacitance (15Fcm−3), energy density (1.3mWhcm−3), power density (up to 214Wcm−3) and excellent stability (more than 13,000 cycles). Furthermore, we show that the PS–TiN nanomaterial can be integrated inside a silicon chip monolithically by combining MEMS and nanofabrication techniques. This leads to realization of in-chip supercapacitor, i.e., it opens a new way to exploit the otherwise inactive volume of a silicon chip to store energy.