Performance Study of Cryogenically Treated HSS Drills in Drillilg Gray Cast Iron Using Orthogonal Array Technique

摘要

The objective of this research was to study the performance of cryogenically treated HSS drills for drilling gray cast iron. Drilling experiments were conducted with cutting speeds: 560, 710, 900, 1120 rpm, feeds: 0.05, 0.08, 0.12, 0.19 mm/rev and a constant drill diameter: 8 mm. The cryogenic treatment cycle consisted of cooling the test samples from room temperature to cryogenic temperature of -178.9oC in 3 h, soaking at cryogenic temperature for 24 h and w arming to room temperature in about 5 h. The thrust force and torque were measured using drill tool dynamometer. The surface roughness (Ra, Rz, Rq and R t) of the drilled specimens were measured using talysurf. The experimental lay-out was designed using Taguchi's Orthogonal Array technique. Signal-to-Noise Ratio analysis was performed to identify the effect of the parameters on the response variables. The treated drills were found superior to the non-treated in all the test conditions in terms of lesser thrust force, torque and also superior surface roughness of the specimens. The tool wear was studied using SEM.