Optimization of surface quality and machining time in micro-milling of glass

Purpose Glass is a brittle material produced from silica, which has fine material properties, Owing to its sophisticated material properties, glass has found wide application in various high-technological fields such as aviation, aerospace, communication, optics, biomedical and electronics. However, glass is known as difficult to machine material because of its tendency to brittle fracture during machining. This paper aims to investigate the effects of cutting parameters on surface quality and machining time during micro-milling of brittle glass components. Design/methodology/approach A comprehensive genetic algorithm-based optimization strategy is used for selection of process parameters such as cutting speed, feed rate and depth of cut. Effectiveness of the proposed strategy is validated by conducting micro-milling cutting experiments on soda-lime glass material. Findings Results showed that the generated surface quality drastically decrease with increase in the amount of removed material. Lower depth of cut and feed rate result in less amount of cracks formed on machined surface. Also, it is observed that the increase in cutting speed results in better surface quality. Having desired surface quality in shorter machining time directly reduces energy consumed during manufacturing, which is reducing environmental impact of glass parts. Originality/value The novelty of this research work lies in simultaneously considering the effects of cutting speed, feed rate, depth of cut on surface quality and machining time for micro-milling operation of brittle glass material. The model is able to find optimum process parameters for high surface quality and minimum machining time.

Modeling metal removal from workpiece surface during centrifugal rotation processing

The modeling and analysis the removal of metal process in centrifugal rotational processing of workpiece in abrasive medium are considered in this article. The single contact interaction process between abrasive particle and the workpiece surface is researched through three-dimensional modeling taking into account dry coefficient of friction. The contact interaction problem is solved through Ansys software and Archard code programmed to analyze the data. The removal of metal from the workpiece surface is researched when changing the technological parameters: friction coefficient, machining time, speed. The dependences between metal removal from the workpiece surface and technological parameters are constructed, from which reasonable parameters can be selected when machining the workpiece, allowing to achieve high accuracy. Experimental results have been confirmed by simulation results. Through this research, essential and important data sheets will be provided for actual production and testing activities. Consequently, time and money are saved in achieving the desired surface quality.

Optimization of Tool Path Length on Three-Dimensional Drilling Application Using Ant Colony Algorithm

The lower machining time is important characteristic in the drilling machining process. Drilling process costs will increase if the machining time is high. Therefore, the main objective of this research is to develop Ant Colony Algorithm (ACO) to reduce the machining time by obtain the optimal tool path length. By using this algorithm, it can minimize the tool path length and significantly decreasing the machining time of drilling process. Simulating in 3-dimensional drilling on ACO has been constructed to minimize the shortest path of the drilling process. There are two type of workpiece has been used, which is simple block with 10 holes and complex block design that has 154 holes. ACO algorithm has been developed in Matlab R2017b to determine the optimal parameters of ACO of tool path length in drilling. Besides, simulation also has been done to investigate the effect of ACO parameter which is weight of pheromone (α), weight of trail (β), evaporation coefficient (e), and number of iterations. As a result, by define the parameter of iteration number at 900, the optimum parameter of weight of pheromone (α) is 5, weight of trail (β) is 4 and evaporation coefficient (e) is 0.4. Based on these parameters, the minimal tool path length obtain for simple and complex model are 286.965 mm and 6770.9860 mm respectively. Then, the result of tool path length of ACO simulation has been compared with the Mastercam outcome. ACO achieves a total tool path length of 286.965 mm while Mastercam achieved 569.878 mm for simple block design. Meanwhile, for complex block design, ACO produces a total tool path length of 6770.9860 mm while Mastercam has generate 55828.9050 mm of tool path length. By comparing these two approaches, ACO and Mastercam, ACO has that the short total tool path length by 49.64% on simple block design and 87.87% for complex block design.

5-axis double-flank CNC machining of spiral bevel gears via custom-shaped tools—Part II: physical validations and experiments

Recently, a new methodology for 5-axis flank computer numerically controlled (CNC) machining, called double-flank machining, has been introduced (see “5-axis double-flank CNC machining of spiral bevel gears via custom-shaped milling tools—Part I: Modeling and simulation”). Certain geometries, such as curved teeth of spiral bevel gear, admit this approach where the machining tool has tangential contact with the material block on two sides, yielding a more efficient variant of flank machining. To achieve high machining accuracy, the path-planning algorithm, however, does not look only for the path of the tool, but also for the shape of the tool itself. The proposed approach is validated by series of physical experiments using an abrasive custom-shaped tool specifically designed for a particular type of a spiral bevel gear. The potential of this new methodology is shown in the semifinishing stage of gear manufacturing, where it outperforms traditional ball end milling by an order of magnitude in terms of machining time, while keeping, or even improving, the machining error.

Enhanced Micro-Electric Discharge Machining-Induced Surface Modification on Biomedical Ti-6Al-4V alloy

In the midst of a huge demand for high-precision miniaturized medical implants made up of potential biomaterials, the biomedical Ti-6Al-4V alloy meets the uncompromising standards for longevity, biocompatibility, and sterilizability required to interact with living cells in medical settings. This research tailored the existing capabilities of a traditional micro-electric discharge machining (μ-EDM) setup by adding 0, 2, 4, 6, 8, and 10 g/l bioactive zinc powder-particle-concentrations (PPCs) to the dielectric. A copper and brass micro-tool electrode (C-μ-TE and B-μ-TE) were employed in association with each PPC, and experiments were executed using one-variable-at-a-time (OVAT) approach. Machining time and dimensional deviation were chosen as the response variables of Zn powder mixed-micro-EDM (Zn-PM-μ-EDM). According to the analytical findings, the combination of C-μ-TE and 6 g/l Zn PPC achieved 23.52 %, 3.29 %, and 17.96 % lesser machining time, dimensional deviation, and recast layer thickness, respectively, compared to the B-μ-TE. The detailed study of this surface endorsed a significant modification in terms of improved recast layer thickness (26.44 μm), topography (Ra = 743.65 nm), and wettability (contact angle < 90°), suggesting its dental application. Additionally, the observation of ZnO and TiO in X-ray diffraction and appealing in vitro cytocompatibility encourage the subsequent biological and therapeutic studies to validate the anticipated anti-viral activity of the modified Ti-6Al-4V alloy surface against coronavirus (COVID-19).

Influence of the Material Properties on Microgrooving u sing Wire Tools Electrodeposited with Diamond Grains

In this study, the main objective is to clarify the relationship between the material properties of the work material and the grooving properties for various work materials from hard and brittle materials to metallic materials. In this paper, in order to investigate the grinding characteristics of diamond electroplated wire tools, including the wear characteristics, we conducted grooving experiments with borosilicate glass (Pyrex), which is a kind of hard and brittle material, and aluminum alloy (A5052), and tough pitch copper (C1100), a kind of metallic material, using diamond electroplated wire tools in a work material rotation method. As a result of the grooving experiments, it was clarified that the grooving characteristics of the work materials were influenced by the hardness and brittle behavior of the materials. The groove depth is influenced by the hardness and brittleness behavior of the material. When machining hard materials, the groove depth increases slowly in the initial stage of machining due to the poor bite of the wire tool, but increases rapidly as the machining progresses. On the other hand, the groove width does not depend on the machining time or speed, but is influenced by the hardness of the material and the ease with which plastic deformation occurs. The wear of the wire tool is also influenced by the hardness and brittleness of the material. In the machining of hard materials, the wear caused by stray wire and vibration in the early stages of machining was significant. The grinding ratio calculated from the ratio of the groove depth to the amount of grinding has a very different trend for hard and brittle materials and metallic materials. In the machining of hard and brittle materials, the amount of machining increased rapidly as machining progressed, so the grinding ratio also increased, but in metallic materials, the amount of machining itself was small and the grinding ratio did not increase. For A5052, the grinding ratio tended to decrease as machining progressed. Future work In the future, it is necessary to clarify the machining conditions to reduce the wear caused by stray wire tools and vibration during the initial machining of hard materials.

An Experimental Investigation on Micro Drilling of Cold Work Steel X153CrMoV12 By EDM

In this study, it was aimed to analyze the effects of machining parameters on the process quality by drilling holes in heat treated cold work tool steel with a hardness of 60-62 HRC using the electrical discharge machining (EDM) method and Ø2 mm diameter brass electrodes. In this context, drilling was performed using three different current values ​​(5, 6, 7 A), three different voltage values ​​(1, 2, 3 V), three different discharge pulse frequency Ton (23, 26, 29 µs) as well as Toff (3, 5 µs) respectively, and the effects of these machining parameters on the machining time, material removal rate (MRR), electrode wear rate (EWR), surface roughness (SR) and hardness of around the white layer were analyzed using micro, macro and analytical measurements, especially with Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX). As a result of the analysis, ıt was observed that current, voltage, Ton and Toff had an effect on machining time, MRR, EWR, SR and hardness, but current was the most effective parameter, and also worn electrode as well as workpiece residues affected the process quality. Increasing the machining current increased sparking between the workpiece and the electrode, resulting in increased point melting and evaporation, resulting in increased average surface roughness, metal removal rate, and electrode wear rate. As a result of the high metal removal rate, the machining time was greatly reduced and the thermal effect time was reduced, which led to a decrease in the hardness variation on the machined surfaces.

Lubrication efficiency of crankpin bearing using square-cylindrical textures of partial textures optimized by genetic algorithm

Purpose This paper aims to propose an optimal design of the partial textures in the mixed lubrication regime of the crankpin bearing (CB) to maximize the CB's lubrication efficiency. Design/methodology/approach Based on a hybrid model between the slider-crank-mechanism dynamic and CB lubrication, the square-cylindrical textures (SCT) of partial textures designed on the CB’s mixed lubrication regime are researched. The effect of the density distributions of partial textures on CB’s lubrication efficiency is then evaluated via two indices of increasing the oil film pressure (p) and decreasing the frictional force (Ff) of the CB. The SCT’s geometrical dimensions are then optimized by the genetic algorithm to further improve the CB’s lubrication efficiency. Findings The results show that the SCT of partial textures optimized by the genetic algorithm has an obvious effect on enhancing CB’s lubrication efficiency. Especially, with the CB using the optimal SCT of partial textures (4 × 6), the maximum p is significantly increased by 3.7% and 8.2%, concurrently, the maximum Ff is evidently reduced by 9.5% and 21.6% in comparison with the SCT of partial textures (4 × 6) without optimization and the SCT of full textures (12 × 6) designed throughout the CB’s bearing surface, respectively. Originality/value The application of the optimal SCT of partial textures on the bearing surface not only is simple for the design-manufacturing process and maximizes CB’s lubrication efficiency but also can reduce the machining time, save cost and ensure the durability of the bearing compared to use the full textures designed throughout the CB’s bearing surface.

Effectiveness of Automatic CAM Programming Using Machining Templates for the Manufacture of Special Production Tooling

The paper presents the methodology and implementation of original Automatic CAM programming using machining templates (ACPUT) dedicated to manufacturing special technological tooling. The development of ACPUT was inspired by the observation that although modern computer-aided design (CAD) / computer-aided manufacturing (CAM) systems can automatically create CAM programs, their universality makes them both difficult to use and inefficient because the programs created this way often contain errors. The presented programming procedure includes the development of specific machining templates based on technological knowledge gathered in a specially prepared database. These templates are dedicated to a group of parts characterized by the similarity of their geometric features. ACPUT makes it possible to reduce(in comparison to traditional CAM programming) the time required to develop a machining program, thereby positively impacting the total cost of tooling production. The paper aims to present results of testing the effectiveness of the use of ACPUT by technicians with different levels of experience (expert and beginner). The tests were carried out on special tooling - assembly equipment for plastic pipes, and compared program preparation time, machining time, and production costs.