Air-assisted boric acid solid powder lubrication in surface grinding: an investigation into the effects of lubrication parameters on surface integrity of AISI 1045

• Published in: International journal of advanced manufacturing technology 2017-08, Vol.91 (9-12), p.3561-3572
• Main Authors: Saleem, Muhammad Qaiser, Ahmad, Abdul Hamid, Raza, Ali, Qureshi, Muhammad Asif Mahmood
• Format: Article
• Language: English
• Subjects: Air flow; CAE) and Design; Computer-Aided Engineering (CAD; Confidence; Confidence intervals; Coolants; Design of experiments; Dry grinding; Engineering; Fatigue life; Flow velocity; Grinding; Industrial and Production Engineering; Integrity; Lubricants; Lubricants & lubrication; Lubrication; Machining; Mechanical Engineering; Media Management; Medium carbon steels; Microhardness; Original Article; Particle size; Residual stress; Stress concentration; Surface grinding; Surface roughness; Variance analysis
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-016-9982-5

Solid powder lubricants provide distinct advantages over conventional coolants in machining applications. Various novel approaches have been used over the years for delivering these lubricants to the machining zone. This work employs air-assisted approach using air as carrier medium and reports on the effects of “lubricant/air mixture ratio,” powder particle size,” and “lubricant laden airflow rate” on surface roughness, microhardness, and residual stresses when AISI 1045 steel is ground with boric acid as lubricant. Nested-factorial mixed model design of experiment is used for structured inquiry; two levels (25 and 96.5 μm) of lubricant “powder particle size” are in factorial arrangement with three levels (1:1/2, 1:1, 1:2) of “lubricant/air mixture ratio.” Three distinct levels of “lubricant laden airflow rate” are nested within the levels of “lubricant/air mixture ratio.” Results show that coarse particles and concentrated mixture give favorable results in general, except for residual stresses. Balanced analysis of variance (ANOVA) reveals that “powder particle size” is statistically significant (95% confidence) for all three response measures whereas “lubricant/air mixture ratio” is significant for microhardness and residual stresses. Further, interaction of “powder particle size” with “lubricant laden airflow rate” is significant for surface roughness and residual stresses. Values obtained with 96.5 μm particle size, 1:1/2 mixture ratio and 0.74 g/s flow rate are within 2% and 22% for microhardness and surface roughness respectively w.r.t. “grinding with conventional coolant”; 7% better microhardness, 48% less surface roughness, and 75% less residual stresses are obtained w.r.t “dry grinding.”