Effect of tool edge preparation and hardness of workpiece on machinability of AISI 1045 steel

Abstract

Intermittent machining using ceramic tools such as hard milling is a challenging task due to the severe mechanical shock that the inserts undergo during machining and the brittleness of ceramic inserts. The main aim of this thesis is to investigate the effects of the workpiece material’s hardness, cutting tool edge preparation (Honed, T-land), inserts grade (Silicon Nitride (SiAlON) based ceramic, Whisker ceramic with a matrix of AI2O3 + SiCW) on the machinability of AISI 1045 hardened steel. AISI 1045 steel workpieces were hardened to 17 HRC, 38 HRC and 48 HRC prior to the machining experiments. In addition to the above mentioned machining conditions, the effects of the machining parameters (feed and speed), milling type (conventional and climb) were also investigated. The indicators tests include resultant cutting force, power consumption, surface roughness and tool wear. The analysis was performed using Taguchi orthogonal array design L32 (21 44 ) and evaluated using statistical tools such as analysis of variance (ANOVA), main effects and interactions. The results of lower resultant cutting forces were obtained with honed edge inserts of SiAlON ceramic grade. In addition, a decrease in resultant cutting forces was associated with the use of low feed rates during machining of hardest material. The feed rate, cutting speed and workpiece hardness were also identified as the greatest influencing factors on the cutting power. Increased flank wear was observed at a low cutting speed and high feed rates, while micro-chipping of the tool mostly ensued from the cyclic loading. The effects of cutting speed, feed rate and workpiece material hardness on the particles number concentration (fine and ultrafine particles) during the milling were also experimentally investigated. The three levels fractional experimental design (L27) was used. The results show that the hardness of the workpiece material was the main factor affecting the generation of fine and ultrafine metallic particles for both cutting tools used. Other significant effects such as the interaction between the milling parameters are also investigated. Overall, it is shown that the use of a cutting tool with a honed edge reduces the metallic particles emission. This thesis can help determine the conditions in which AISI 1045 steel should be machined in order to enhance tool performance and improve the surface quality of the machined part while minimizing the emission of fine and ultrafine metallic particles.

Date	11 May 2020
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Victor Songmene (Supervisor)