Identification of Instabilities of the Chip Formation and It’s Prediction Model During End Milling of Medium Carbon Steel (S45C)

Abstract

Problem statement: Chip shape and size varied widely in machining operations. Undesirable chip formation had a detrimental effect on surface finish, work-piece accuracy, chatter and tool life. Approach: This study included the findings of an experimental study on the instabilities of the chip formation and development of a mathematical model based on statistical approach for the prediction of the instability of chip formation during the machining of medium carbon steel (S45C). Results: It has been identified that the chip formation process has a discrete nature, associated with the periodic shearing process of the chip. Typical instabilities of periodic nature, in the form of primary and secondary saw/serrated teeth, which appear at the main body and free edge of the chip respectively, have been identified. Mechanisms of formation of these teeth have been studied and the frequencies of their formation have been determined under various machining conditions. Small Central composite design was employed in developing the chip serration frequency model in relation to primary cutting parameters by Response Surface Methodology (RSM). Conclusion/Recommendations: The mathematical model for the chip serration frequency has been developed, in terms input cutting parameters (cutting speed, feed and depth of cut) in end milling of S45C steel using TiN inserts under full immersion. The adequacy of the predictive model was verified using ANOVA at 95% confidence level.

Influence of cutting environments on surface integrity and power consumption of austenitic stainless steel

“…This result matches with the power consumption results, where a 600% of increase of this value was observed when using a cryogenic environment compared to the dry environment. This result is in agree with previous research [15].…”

A Study of Parameters Relationship to Backcutting Phenomena During High Speed End Milling of AISI H13

“…RSM is a collection of mathematical and statistical techniques that are useful for the modeling and analysis of problems in which a response of interest is influenced by several variables and the objective is to optimize this response. RSM also quantifies relationships among one or more measured responses and the vital input factors (Patwari et al, 2010). The results are tabulated in Table 2 together with the arithmetic average roughness (Ra) and maximum peak-to-valley height (Rt).…”

Effects of Milling Methods and Cooling Strategies on Tool Wear, Chip Morphology and Surface Roughness in High Speed End-Milling of Inconel-718

“…Figure 14 shows images of chips collected after the first, fifth and eighth pass for emulsion up and down-milling. It has been seen that the chips formed in end-milling are serrated in nature (Patwari et al, 2010). The major section of the lamella in the free surface was formed by side cutting edge and the corner section was formed by the corner cutting edge (Sun and Guo, 2008).…”

“…The major section of the lamella in the free surface was formed by side cutting edge and the corner section was formed by the corner cutting edge (Sun and Guo, 2008). This major section of lamella formed by side cutting edge was saw teeth in nature which was produced due to phase compression and adiabatic shear, resulting in fluctuation of the force exerted on tool (Patwari et al, 2010). There was a long tail obtained in first pass of emulsion up-milling experiment which is formed by tool nose radius as seen in Figure 13(a).…”

“…Sun and Guo (2008) presented a new multi-view approach to characterise the chip morphology including top, free, back and cross section surfaces of the chips in end-milling of Ti-6Al-4V using flood coolant. Patwari et al (2010) identified primary and secondary saw/serrated teeth appeared at the free edge of the chip as the instabilities of periodic nature using a mathematical model in machining of medium carbon steel (S45C).…”