China
Africa
Explore chapters and articles related to this topic
Molecular Dynamics Simulation of Advanced Machining Processes
Published in V. K. Jain, Advanced Machining Science, 2023
Xichun Luo, Xiaoguang Guo, Jian Gao, Saurav Goel, Saeed Zare Chavoshi
Figure 14.1 shows the evolution of achievable machining accuracy over the years, which keeps on improving with the development of ultra-precision machine tools, and new machining and measurement technologies. Ultra-precision diamond turning is at the pinnacle of the advanced machining process range in terms of accuracy and productivity, as it can create ultra-precision components with sub-micrometer form accuracy and nanometer surface finish by using a diamond tool in a single cut. One issue with diamond turning is that these processes leave tool feed marks on the machined surface which poses problems in using these components for extremely delicate jobs e.g., mirrors for x-rays and laser beam splitters produced by roll-to-roll embossing process. In such cases, ultra-precision polishing process needs to be adopted as a post-processing finishing operation to remove cutting tool feed marks and any subsurface damage left by previous ultra-precision manufacturing operations.
Plastic Optics
Published in Anees Ahmad, Handbook of Optomechanical Engineering, 2017
Machining of plastics is a common method of small quantity production of optics. While it is possible to polish optical plastics, this is not usually the first choice, unless the part is so large or unusual as to prevent it from being fabricated by more standard machining techniques. The machining of optical surfaces on plastics is typically performed by single-point diamond turning. Usually referred to as diamond turning, this machining method relies upon the use of extremely high-precision lathes and diamond cutting tools. Ongoing advances in diamond turning machines, techniques, and understanding have made it possible to generate optical surfaces on plastic that require no additional polishing—the parts come off the diamond turning lathe ready for coating or use. Multiple axis capability and tool servo mechanisms allow the generation of asymmetric, off-axis, or freeform parts.
Electric Discharge Hybrid-Turning Processes
Published in Basil Kuriachen, Jose Mathew, Uday Shanker Dixit, Electric Discharge Hybrid-Machining Processes, 2022
Jees George, R. Manu, Jose Mathew
Turning is a type of manufacturing process; a metal removal process, for the generation of cylindrical components by removing the undesired material. Additionally, turning can also be utilized to produce parts having various features, for example, grooves, tapers, holes, different diameter steps and contoured surfaces. Turning on a lathe is one of the oldest techniques for manufacturing cylindrical products that is still relevant today. The process consists of a rotational unit which holds the workpiece (the headstock assembly) and a cutting tool (made of high-speed steel, carbide, carbon steel, cobalt high-speed steel, and the like). Another important variant of the turning operation is the turning machine which can be controlled with the help of a computer, referred to as a computer numerically controlled (CNC) lathe. The workpiece rotation and movement of the cutting tool of a CNC lathe in the desired path is based on the commands pre-programmed into the computer, and this offers high precision. Diamond turning is yet another ultraprecision conventional turning process for the generation of intricate surfaces and ultra-fine microstructures with the aid of geometrically defined diamond cutters. Diamond turning is mainly utilized to generate ultra-high precision components, which have exceptional levels of form precision and surface finish for advanced industrial applications. In the early days, diamond turning was primarily used to manufacture optical components like lenses and reflectors, which are usually machined directly from stock material. However, now the process has been found to have wide applications in various industries, such as the aerospace, electronics, biomedical and defense and semiconductor industries [5]. Nevertheless, one of the major drawbacks of diamond turning is its inability to turn ferrous materials due to the excessive diamond tool wear while turning them [6]. Micro turning is one of the most popular conventional turning technologies to produce miniaturized cylindrical parts and components. It consists of a solid tool to remove material with a different cutting mechanism compared to the macro turning process. In the macro turning process, material is mainly removed by shearing bulk material along the average shear plane with high defect density and this forms a larger chip cross section. On the other hand, in case of micro turning, the material is removed across the grains, where the size effect becomes a dominant factor that leads (significantly) to a high specific cutting energy. One of main disadvantages of using conventional micro turning is its inability to turn difficult-to-machine material beyond 100 μm as forces exerted by the tool leads to the deflection of the micro-electrode and it often breaks during the turning process.
Tool vibration effect on surface roughness of polymethylmethacrylate in diamond turning
Published in Materials and Manufacturing Processes, 2022
Kuldeep A Mahajan, Raju S. Pawade, Vinod Mishra
The comparison of experimental GRG with the multiple regression model is given in Table 6, and it shows close agreement between the points. The average error amongst the experimental GRG and multiple regression GRG is less than 7% and a maximum 20%. Hence, this multiple regression model depicts an excellent correlation between the predicted and experimental results. This can be beneficial to reduce experimental work on single-point diamond turning machine to accomplish improved surface roughness and reduced vibration signature on the workpiece.