IMPACT OF CUTTING PARAMETERS ON SURFACE QUALITY DURING MILLING OF AISI 1055 AND AISI 4140 STEELS

This study explores and contrasts the surface roughness caused by milling AISI 1055 steel and AISI 4140 steel. The materials underwent heat treatment, especially quenching and tempering at different temperatures. The evaluation was performed utilizing both multifactorial and unifactorial methodologies. The testing used a complete factorial design with eight variants, and the sample size was 23 (N = 8). The findings indicate that an increase in rotation frequency N correlates with a reduction in surface roughness Ra for both materials across different tempering temperatures. At a tempering temperature of 550 °C, the surface roughness Ra values are much higher for both materials than at lower temperatures (200 and 300 °C). Additionally, test No. 5 indicates that the ideal surface quality for the AISI 1055 material was achieved when tempered at 550 °C. Analysis of variance (ANOVA) was utilized to assess the effect of cutting parameters on surface quality. The feed rate (f) was determined to be the principal factor for the two materials examined, while the rotation frequency (N) served as the secondary effect. Two mathematical methods are presented to quantify Ra, the surface roughness of the two materials. Finding the appropriate cutting settings using MATLAB software resulted in a 35% increase in the surface quality of AISI 1055 steel compared to AISI 4140 steel. To achieve improved surface quality when milling materials treated at elevated tempering temperatures, it is recommended to use AISI 1055 steel instead of AISI 4140 steel.