Analysis of the surface roughness, cutting efforts, and form errors in bore reaming of hardened steel using a statistical approach

Abstract

Drilling is a primary machining process used to produce holes. However, in some situations drilling generates unsatisfactory technical specifications. Thus, reaming is a machining process that improves the quality of drilled holes produced by twist drills. In this paper, experimental tests with reamer were carried out in CNC three-axis machining-centre where the main objective was to understand the influence of the kind of flute, lubrication system, feed rate and cutting speed in the reaming process in the AISI P20 hardened steel. The evaluated responses were thrust force, torque, surface roughness, roundness and cylindricity errors, measured by a piezoelectric dynamometer, surface roughness tester, and an equipment to measure the roundness and cylindricity errors, respectively. The results demonstrate that cutting speed was the most critical input parameter to define the best standard quality on the hole wall and the lowest thrust force. Furthermore, helical flute reamer had an important influence on surface roughness and thrust force. On the other hand, the feed rate was the most important input parameter in torque. Lubrication using emulsion system presented better results for the torque, and the MQL system provided better results for the roundness error. Finally, none of the studied input parameters had statistically significant influence in the cylindricity error.