In this study, the tool performance of two types of binderless diamond tools – single-crystal diamond (SCD) and nano-polycrystalline diamond (NPD) – is investigated in the high-speed cutting of titanium alloy (Ti-6Al-4V) with a water-soluble coolant. The NPD tool allows for a larger cutting force than the SCD tool by dulling of the cutting edge, despite NPD being harder than SCD. This large cutting force and the very low thermal conductivity of NPD yield a high cutting temperature above 500°C, which promotes the adhesion of the workpiece to the tool face, thereby increasing tool wear. Based on the morphology of the tool edge without scratch marks and the elemental analysis by energy-dispersive X-ray spectroscopy (EDX) of both the flank face and the cutting chips, diffusion-dissolution wear is determined to be the dominant mechanism in the diamond tool. A thin TiC layer seems to be formed in the boundary between the diamond tool and the titanium alloy at high temperatures; this is removed by the cutting chips.
One of the most significant factors in machining process or metal cutting is the cutting tool performance. The rapid wear rate of cutting tools and cutting forces expend due to high cutting temperature is a critical problem to be solved in high-speed machining process, milling. Near-dry machining such as minimum quantity lubrication (MQL) is regarded as one of the solutions to solve this problem. However, the function of MQL in milling process is still uncertain so far which prevents MQL from widely being utilized in this specific machining process. In this paper, the mechanism of cutting tool performance such as tool wear and cutting forces in MQL assisted milling is investigated more comprehensively and the results are compared in three different cutting conditions which is dry cutting, wet cutting (flooding) and MQL. The MQL applicator is constructed from a household grade low-cost 3D printing technique. The chips surface of chips formation in each cutting condition is also observed using Scanning Electron Microscopy (SEM) machine. It is found out that wet cutting (flooding) is the best cutting performance compare to MQL and dry cutting. However, it can also be said that wet cutting and MQL produced almost the same value of tool wear and cutting forces as there is negligible differences in average tool wear and cutting forces between them based on the experiment conducted.
This research deals with the hard turning of cemented carbide with CBN and diamond tools, and focuses on the tool performance, mainly tool wear with respect to cutting force and cutting temperature. The internal turning tests without cutting fluid are executed with the vertical machining center. Seven types of tool materials: SC, CVD-SC, two PCDs, BL-NPD (Binderless nano-polycrystalline diamond) and CBN: are selected for cutting three grades of cemented carbides WC having the different Co binder content (12%, 20% and 25%). Attrition has been found to be the main tool wear mechanism for all tools with slight adhesion of the workpiece binder on the tool face. In cutting of softest carbide WC-m (25% Co), the polycrystalline CBN tool has the lowest tool wear than any other PCD tools. In turning of harder carbides WC-d (20% Co) and WC-t (12% Co), both polycrystalline CBN and PCD cannot be used continuously due to their low hardness, and BL-NPD, SC and CVD-SC tools are applicable. And the BL-NPD tool has the best cutting performance with less flank wear. As for WC-d, extremely stable cutting can be done with BL-NPD where the principal cutting force is kept almost constant at 40 N. Only BL-NPD tool can continue to turn the hardest WC-t. In spite of turning hard materials, the tool temperatures measured are relatively low below 450°C due to the high thermal conductivities of tool materials. However, cutting temperature is directly related to the tool wear and cutting force rather than thermal conductivity of tool in turning of WC-m and WC-t.
Background The revolutionary technology of smartphone-based retinal imaging has been consistently improving over the years. Smartphone-based retinal image acquisition devices are designed to be portable, and easy to use, besides being low-cost which enables eye care to be more widely accessible especially in geographically remote areas. This enables early disease detection for those who are in low- and middle- income population or just in general has very limited access to eye care. This study investigates the limitation of smartphone compatibility of existing smartphone-based retinal image acquisition devices. Additionally, this study aims to propose a universal adapter that is usable with an existing smartphone-based retinal image acquisition device, the PanOptic ophthalmoscope. This study also aims to simulate the reliability, validity, and performance overall of improved develop prototype. Existing studies have shown that the concept of smartphone-based retinal imaging is still limited to screening purposes only. Furthermore, existing smartphone-based devices also have a limited smartphone compatibility where it is only usable with specific smartphone models. Methods A literature review was conducted that identifies the limitation of smartphone compatibility among existing smartphone-based retinal image acquisition devices. Designing and modelling of proposed adapter was performed using the software AutoCAD 3D. For proposed performance evaluation, finite element analysis (FEA) in the software Autodesk Inventor and 5-point scale method were applied. Results It was identified how a universal adapter is beneficial in broadening the usability of existing smartphone-based retinal image acquisition devices as most of the devices that are available in the market have limited smartphone compatibility. A functional universal adapter was developed and found to be suitable with two smartphones that have different camera placement and dimensions. The proposed performance evaluation method was able to generate efficient stress analysis of the proposed adapter design. Conclusion The concept of a universal and suitable adapter for retinal imaging using the PanOptic ophthalmoscope was presented in this paper. Performance evaluation methods proposed were identified to be sufficient to analyze the behavior of proposed adapter when an external load is applied and determine its suitability with the PanOptic ophthalmoscope.
This study investigated how to model a centre-offset annular rotary drum using OpenFOAM and the meshing software GMSH. The diameter of the outer cylinder is 600 mm, diameter of the inner cylinder 200 mm, the centre-offset mm, and rotation rate rpm. When the centre-offset is zero, the quality of mesh is preserved as the drum rotates. Introduction of the offset causes the mesh to be deformed to the point of being unusable as the drum is rotated. The reason was found to be the fixed nodes adjacent to the walls of the outer and inner cylinder. These nodes only respect the motion of the wall they are adjacent to. To circumvent this, we separated the inner volume of the rotary drum to allow the implementation of an OpenFOAM dynamic mesh handling scheme called arbitrary mesh interface (AMI). Implementing AMI allows the quality of the mesh to be kept even when the inner cylinder is rotating under nonzero-offset conditions. This is because AMI permits the sliding of non-conforming meshes next to each other. This preserves the quality of the mesh and secures a reliable and reproducible dynamic mesh motion for the implementation of the drying process in the future.
This paper describes the development of cutting temperature measurement of end mill tool by using infrared radiation technique approach. Compared to conventional thermocouple technique, infrared radiation technique is an advance method of measuring temperature which featured high accuracy, high response rate, wide range of temperature scale detection and almost compatible with all materials used in the manufacturing industry. We measures the emission of infrared radiation from the source, which is cutting edge of tool by using photocells that contains InAs and InSb photovoltaic detectors. Photocells converts the infrared radiation to a voltage signal and then recorded by oscilloscope followed with a calibration with its corresponding temperature. This paper discussed about the calibration method, cutting experiment setup, the limit of infrared radiation level detected by photocells, signal correction of output signal, and relations of peak signal formation with rotation of end mill tool. The developed pyrometer is also capable to profile the cutting tool’s rotation based on the movements of infrared radiation’s emission at cutting tool’s edge. The conclusion was that the measurement of cutting temperature of high speed machining by using infrared radiation technique is possible. The developed pyrometer are capable to detect temperature changes at a span of 0.01 ms.
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