Role of Ball and Coating Materials under Unlubricated Condition
Suresha Gowda M. V.1, Ranganatha S.2, Vidyasagar H. N.3
1Suresha Gowda M .V, Department of Mechanical Engineering, University Visweswaraya College of Engineering, Bangalore, Karnataka, India.
2Dr. Ranganatha S, Department of Mechanical Engineering, University Visweswaraya College of Engineering, Bangalore, Karnataka, India.
3Dr. Vidyasagar H . N, Department of Mechanical Engineering, University Visweswaraya College of Engineering, Bangalore, Karnataka, India.
Manuscript received on 20 July 2016 | Revised Manuscript received on 30 July 2016 | Manuscript published on 30 July 2016 | PP: 12-24 | Volume-5 Issue-3, July 2016 | Retrieval Number: C1605075316©BEIESP
Open Access | Ethics and Policies | Cite | Mendeley | Indexing and Abstracting
© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: The performance, reliability and load transferring capabilities of bearing elements are very important in industrial applications. The newer design of high speed machines demands better bearing system. The reliability is of primary importance in case of bearing elements used in aerospace industries. Exhaustive studies have been carried out by different researchers under two extreme conditions. One is using a fluid as lubricants which do not bear shear loads. The other extreme were using hard coatings which bears enormous amount of shear loads. In the present investigation an attempt has been made to understand the kinematics of deformation of balls and coatings which are not as hard as conventional coatings without lubricants. Different ball materials like case hardened carbon steel, high carbon high chromium steel and stainless steel, case hardened carbon steel and high carbon high chromium steel balls were coated with tin and case hardened carbon steel and stainless steel balls were coated with zinc by electroplating coating technique. The thickness of the coating was maintained at 25 µm. Four ball test rig was used to simulate the field condition. The experiments were conducted without lubricants. The normal loads were 100N, 300N and 500N respectively for case hardened carbon steel and high carbon high chromium steel, run for a period of 5 minutes. The normal loads were 50N, 75N and 100N respectively for stainless steel and run for a period of 5 minutes. The frictional load and normal load were monitored and co-efficient of friction was estimated. The wear scar was studied under scanning electron microscope. The co-efficient of friction was found to be dependent on normal load and type of coating material. The coefficient of friction was found to be minimum of value 0.27 for a maximum normal load of 500N for tin coatings and 0.41 for a maximum load of 500N for zinc coatings. The morphology of wear scar studied in scanning electron microscope explains the dependency of co-efficient of friction on normal load and different coating materials.
Keywords: Rolling contact fatigue, four ball tester, Coatings
Scope of the Article: Materials Engineering