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Surface Hardness Prediction Model of Turning Duplex Stainless Steel under Different Cutting Variables

100%

Abdulateef O. F. , Ali A. H. , Al Kareem S. S. A.

tom Vol. 17, no 1

1--7

The quality of machine components surfaces plays an important impact on their functional performance. Product performance may be restricted by changes to surface integrity, which includes changes to roughness, hardness, and microstructure. In this research, the impact of cutting variables in CNC turning under the conventional cooling condition on surface hardness of Duplex Stainless Steel. Cutting variables under conventional cooling, including cutting speed, feed, and depth of cut, have been optimized utilizing Taguchi’s L9 orthogonal array designed with three stages of turning variables. The optimal variable stages and the degree of significance of the cutting variables, respectively, were determined utilizing the analysis of means (ANOM) and analysis of variance (ANOVA). Effectiveness tests with optimum stages of variables were done to prove the viability of optimization by utilizing Taguchi. It has been found that the maximum surface hardness is most strongly affected by the feed 71.29%, followed by the depth of cut 12.1%, and finally the cutting speed 11.61%.

Intelligent identification of cutting states by utilising Power Spectrum Density

63%

Tangjitsitcharoen S.

Journal of Achievements in Materials and Manufacturing Engineering

2008

tom Vol. 31, nr 2

580-587

Purpose: This paper presents an in-process monitoring and identification of cutting states in turning process in order to realize the intelligent machine tools. Design/methodology/approach: The developed method utilizes the power spectrum density, or PSD of dynamic cutting force measured during the cutting. The experimentally obtained results suggested that there are basically three types of patterns of PSD when the cutting states are the continuous chip formation, the broken chip formation, and the chatter. The broken chip formation is desired to realize safe and reliable machining. The method proposed introduces three ratios, which are calculated and obtained by taking the ratios of cumulative PSD for a certain frequency range of three dynamic cutting force components corresponding to those three states of cutting, to classify the cutting states. The algorithm was developed to calculate the values of three ratios during the process in order to obtain the proper threshold values for classification of the cutting states. Findings: The method developed has been proved by series of cutting experiments that the states of cutting are well identified regardless of the cutting conditions. The broken chips are easily obtained by changing the cutting conditions during the processes referring to the algorithm developed. Practical implications: There are still not many systems being used in practice mainly due to the lack of general applicability such as a requirement of automated machining systems regardless of the cutting conditions. The aim of this research is to develop an in-process monitoring system for identification of continuous chip, broken chip, and chatter regardless of the cutting conditions by spectrum analysis based on the power spectrum density, or PSD of dynamic cutting force measured during the cutting. Originality/value: The largest potential advantage of the method proposed in this paper is that the states of cutting can be readily identified during the in-process cutting under any cutting conditions by simply mapping the experimentally obtained values of parameters referring to the proper threshold values in the reference feature spaces.

The effect of aging on machinability of 15Cr–5Ni precipitation hardened stainless steel

63%

Palanisamy D. , Senthil P. , Senthilkumar V.

tom Vol. 16, no. 1

53--63

This study is an attempt to correlate the microstructure and mechanical properties of commercial 15Cr–5Ni precipitation-hardening stainless steel in different aging regimes such as solution treated (Condition A), over-aged (Condition H1150-M) and peak-aged (Condition H900) with their machinability behavior. Aging was done on 15Cr–5Ni precipitation-hardenable stainless steel samples in a temperature range of 480–760 °C. Over aging of the above material resulted in an improvement of ductility and a substantial reduction in tensile strength. Heat treated samples were machined in order to study the effects of machining parameters on machinability aspects such as cutting forces, surface roughness, chip morphology and tool wear. Experimental investigation revealed a strong correlation between the rate of cooling after aging and cutting forces. Air cooled samples exhibited higher cutting forces compared to furnace cooled samples. The surface finish is found to be improved for H900 air cooled sample, which has higher hardness than that of as received sample and H1150-M condition.