Faculty Publications

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Machinability studies on 17-4 PH stainless steel under cryogenic cooling environment
(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2017) Sivaiah, P.; Dupadu, D.
Under higher cutting conditions, machining of 17-4 precipitation hardenable stainless steel (PH SS) is a difficult task due to the high cutting temperatures as well as accumulation of chips at the machining zone, which causes tool damage and impairment of machined surface finish. Cryogenic machining is an efficient, eco-friendly manufacturing process. In the current work, cutting temperature, tool wear (flank wear (Vb) and rake wear), chip morphology, and surface integrity (surface topography, surface finish (Ra), white layer thickness (WLT)) were considered as investigative machinability characteristics under the cryogenic (liquid nitrogen), minimum quantity lubrication (MQL), wet and dry environments at varying cutting velocities while machining 17-4 PH SS. The results show that the maximum cutting temperature drop found in cryogenic machining was 72%, 62%, and 61%, respectively, in contrast to dry, wet, and MQL machining conditions. Similarly, the maximum tool wear reduction was found to be 60%, 55%, and 50% in cryogenic machining over the dry, wet, and MQL machining conditions, respectively. Among all the machining environments, better surface integrity was obtained by cryogenic machining, which could produce the functionally superior products. © 2017 Taylor & Francis.
Sustainable diamond burnishing of 17-4 PH stainless steel for enhanced surface integrity and product performance by using a novel modified tool
(Institute of Physics Publishing helen.craven@iop.org, 2019) Sachin, B.; Narendranath, S.; Dupadu, D.
Amajor sustainability concern of manufacturing industries is indiscriminate use of lubrication, energy consumption, and allied cost. To avoid such kind of situation and to improve the product quality, sustainable manufacturing concept has been widely used. One of the popular technique is the use of Minimum Quantity Lubrication (MQL) as a working fluid to improve the product performance. Diamond burnishing underMQLenvironment is an exceptional technique to obtain the improved surface integrity of the material without affecting operator health and environmental aspects. In this work, the impact of control factors on the surface integrity characteristics namely surface roughness, surface topography, surface hardness, surface morphology, residual stress and subsurface hardness of 17-4PHstainless steel have been studied underMQLenvironment by using a novel modified tool. It was ensured that minimum surface roughness of 0.05 ?mand maximum surface hardness of 405HV had been achieved. Improved surface finish and surface hardness were obtained for a diamond sphere radius of 4mmand 3mmrespectively under optimal diamond burnishing conditions. The obtained investigational results confirm that a novel modified tool was successfully implemented to enhance the surface integrity characteristics under theMQLenvironment. © 2019 IOP Publishing Ltd.
Effect of working parameters on the surface integrity in cryogenic diamond burnishing of 17-4 PH stainless steel with a novel diamond burnishing tool
(Elsevier Ltd, 2019) Sachin, B.; S, N.; Dupadu, D.
The productivity of the components is adversely affected by the poor surface integrity characteristics as a consequence of the generation of high temperature in the burnishing zone. The abundant use of conventional lubricants causes environmental pollution and health problems. To overcome these issues, cryogenic cooling has been used across the world to reduce the temperature generated in the burnishing zone. It is well known that most of the accidents which involve aero engines have revealed that the reason for this may be due to the failure of the first stage of compressor blades. Hence aerospace material, 17-4 precipitation hardenable (PH) stainless steel can be used in aero engines to minimize the failure occurring due to foreign object damage. In the present study, the effect of cryogenic diamond burnishing on the surface integrity characteristics such as surface roughness, surface hardness, surface morphology, surface topography, subsurface microhardness, and residual stress of 17-4 pH stainless steel have been investigated with a novel diamond burnishing tool and also it has been related to dry and minimum quantity lubrication (MQL) environments. From the experimental results of diamond burnishing process, surface roughness was observed to be reduced by 33%–50%, 34%–51% and 25%–40% in the cryogenic cooling environment in contrast with MQL and dry environments. Similarly, the surface hardness improvement in a cryogenic cooling environment was found to be 5%–7%, 6%–10%, and 6%–9%, in comparison with MQL and dry environments respectively. © 2019 The Society of Manufacturing Engineers

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