Krishnaraj Production 2017 Short Resume (original) (raw)
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REVIEW OF NEW DEVELOPMENTS IN MACHINING OF AEROSPACE MATERIALS
Journal of Machine Engineering, 2021
The paper presents an update of the recent literature on advances in machining of difficult to machine materials such as nickel and titanium-based alloys, and composites used in aeroengine and aerostructure applications. The review covers the following issues: advances in high-performance cooling techniques as cryogenic machining, minimum quantity lubrication, the combination of MQL and cryogenic cooling, and high-pressure lubricoolant supply and hybrid cutting processes-vibration assisted machining (both low and high frequency), laser, plasma and EDM assisted machining. Examples of applications in industrial processes are also given.
2017
Metal –Matrix composites (MMCs) are relatively new class of materials characterized by lighter weight and greater wear resistance than conventional materials. Considering that cutting conditions regulate the machining process, through developed cutting forces, the surface finish of the pieces for machining and tool life, it becomes of high importance for the optimization of machining parameters. MMC material is prepared by using the furnace. The prepared material involves the drilling process, at the time speed, feed and depth of cut are the input parameters mean while surface finish, thrust force, torque and tool wear are the output parameters. Output is obtained by connecting the drill tool dynamometer is connected with the Radial drill machine. The cutting tool wear is measured with a Mitutoyo shop microscope with 30x magnification and 1 μm resolution. The surface finish is evaluated with a profilo meter. The machining parameters are tabulated by using Taguchi techniques. Point o...
Machinability and Chip Formation of Titanium Metal Matrix Composites
properties over titanium alloys. Therefore, this material has recently been used in several applications in the aerospace and automotive industries. Although the TiMMC parts are made near net shape, a finish machining operation is often necessary to achieve the required surface finish and dimensional accuracy. In general, MMCs have been known to be difficult to cut materials, since the added ceramic hard particles are very abrasive and limit the tool life. Titanium alloys are also known to be problematic in machining; therefore, TiMMC combines both machining problems associated with MMCs and titanium alloys. Since data on the machinability of TiMMC is very limited in the open literature, this paper focuses on comparing the performance of different tools under different cutting parameters in order to find the optimum cutting conditions within the constraints of maximum surface integrity and tool life. This research revealed that Poly-Crystalline-Diamond (PCD) tools substantially outperform coated carbide tools. Moreover, chip formation has been carefully studied to understand the interaction of the added Titanium Carbide (TiC) particles with the cutting tool. Contrary to other materials, cutting of TiMMC at higher speeds was found to be more advantageous and resulted in a higher tool life. Analysis of the chip morphology also revealed that the chip formation at high speeds is clearly different from that at lower speeds, suggesting a different cutting mechanism.
International Journal of Machine Tools and Manufacture, 2016
Titanium Metal Matrix Composite (Ti-MMC) is a relatively new class of material, which has high potential applications in the aeronautical and biomedical sectors. Similar to titanium alloys, Ti-MMC produces segmented chips, which are characterized by Adiabatic Shear Bands (ASB). Transmission Electron Microscopy (TEM) observations were performed and dislocations were observed on the atomic scale. Furthermore, the sheared surfaces, as well as the effects of the hard TiC particles on the ASB formation were investigated. It was shown that the grains located in the lightly strained areas within the chip segment are characterized by a high dislocation density. This is contrary to the highly strained areas inside the ASB, where the temperature was estimated to be close to the recrystallization temperature. Analysis of the results showed that no phase transformation took place inside the ASB. The strain and strain rate in the ASB were estimated to reach 7.5 and 4.5x10 5 s-1 , respectively. Using TEM and Focused Ion Beam (FIB) for sample preparation, the microstructure inside the ASB was found to be composed of elongated and equiaxed nano-sized grains. The segmentation mechanism of chips was observed to start from a crack on the material free surface ahead of the tool, and not at the tool tip. Furthermore, the hard particles inside the matrix were found not to be hindering, or retarding the ASB formation. A microstructural evolution model, based on these observations, has also been proposed. To the authors' best knowledge, TEM studies of ASB for Ti-MMC were never done previously for machining applications.
Low Environmental Impact Machining Processes of Composite Materials Applied to the Aerospace Sector
Advanced Materials Research, 2010
In the last decades, technologically innovative processes performed in advanced materials such as Carbon Fibre (CF) and Metal Matrix Composites (MMC) have continuously increased because of these materials find increasingly applications in the most of the industrial sectors, particularly in aeronautical industry. This is caused by their excellent relationship weight/mechanical properties. Although there is a high trend to apply and develop non-conventional technologies and methods for machining CF and MMC, other common machining processes are commonly applied for working these materials. Thus, in aeronautical industry, mechanical drilling processes are usually applied for preparing the manufactured elements to be assembled. However, drilling of CF based materials can carry on troubles related to a loss of surface finishing quality and/or quick and high tool wear. This work reports on the results about an evaluation process of the surface quality of drilled CF samples as a function of the cutting conditions and the tool materials.
MATEC Web of Conferences, 2020
As one of the most common Titanium alloys, Ti-6Al-4V faces new challenges concerning the ecological footprint. Due to the current processes, a high metal chip pollution leads to a Buy-to-Fly of 25:1. In this study the parameter / microstructure relationship of Ti-64 on the mechanical properties are discussed. Wire Arc Additive Manufacturing (WAAM) was applied to build samples for microstructural analyses and compression tests. A stress relief (SR) and a solution treatment and annealing (STA) was performed. It was found that SR had no influence on multi-layered samples due to intrinsic heat-treatment. A STA heat-treatment led to a reduction in the mechanical strength. Helium as process gas resulted in an increased mechanical strength due to higher heat capacity compared to argon.