Manufacturing Technology Today

G. Murali ¹, M. Gopal ², A. Rajadurai ³

Affiliations
1 School of Mechanical Engg., S R M University, Chennai, IN
2 D.M. I. College of Engg., Chennai, IN
3 Dept. of Prod. Technology, MIT, Anna University, Chennai, IN

Abstract

Drawbeads are often applied in the deep drawing process to improve control of the material flow during the forming operation. Drawbeads restrain the sheet from flowing freely into die cavity. This paper deals with analysis of effect of draw bead geometry in sheet metal drawing process. Finite element analysis of drawing of circular blanks into axi-symmetric hemispherical cup is done. Circular and rectangular drawbeads are introduced into the finite element models and their influence in distribution of strain and thickness are investigated. DYNAFORM and LS-DYNA, a commercially available explicit FEA code were used to model and analyze the forming process respectively. These outcomes are compared with experimental results. The results show good agreement between numerical method and experiment. On comparison, rectangular drawbeads restrain the material more than circular drawbead due to their geometry.

Keywords

Sheet Metal Forming, Drawbead, LS-DYNA, Plastic Strain.

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M. Pradeep Kumar ¹, K. S. Vijay Sekar ¹, A. Rajadurai ²

Affiliations
1 Dept. of Mech. Engg., CEG, IN
2 Dept. of Production Engg, MIT, Anna University, Chennai, IN

Abstract

This paper presents a comparative study of the effect of two different flow stress models on the orthogonal metal cutting process using the FEM. The flow stress models used were the Oxley's model and the modified Johnson and Cook model. The orthogonal cutting experiments were conducted with AISI 1045 steel work material and tungsten carbide cutting tool. The FEA results with modified Johnson's model for the cutting force, feed force, chip thickness, shear angle and shear strain compared well with the experimental values with only a marginal deviation of 10-20% for feed rates of 0.16mm/rev and above while the deviation for Oxley's model was higher across most feed rates. The Oxley model gave better results for the FE predictions of contact temperature. This study suggested that the modified Johnson and Cook model was an efficient alternative tool for FE simulation of the orthogonal metal cutting process.

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R. Ramadoss ¹, A. Rajadurai ¹, S. Venugopal ², S. Satishkumar ³

Affiliations
1 Department of Production Technology, Madras Institute of Technology, Chrompet, Anna University, Chennai-600044, IN
2 Metal Forming and Tribology Section, Indira Gandhi Center for Atomic Research, Kalpakkam, IN
3 Department of Mechanical Engineering, St. Joseph’s College of Engineering, Chennai-600119, IN

Abstract

Austenitic stainless steels are special grades of steels with improved corrosion resistance and oxidation resistance. In this work forming limit diagrams (FLDs) for Austenitic stainless steels of grades AISI 316 and 316L of thickness 1.25mm have been studied and their suitability for forming applications have been examined. FLDs were experimentally found using the hemispherical punch forming test. The micro structural aspects, tensile properties, formability parameters of the above mentioned steels were studied and compared. The fracture surfaces of the formed samples were viewed using the scanning electron microscope (SEM) and the SEM images were correlated with the fracture behavior and formability of the sheet metal. It was found that the formability of AISI 316L posses good drawability and stretchability.

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R. Ramadoss ¹, A. Rajadurai ²

Affiliations
1 Department of Mechanical Engg., St.Joseph’s College of Engg., Chennai, IN
2 Dept. of Production Technology, Madras Institute of Technology Chrompet, Anna University, Chennai, IN

Abstract

Many of the stainless steel components ore manufactured through forming. Therefore on understanding of formability sheet metal is essential for successful prediction of quality stomping. In the present work, the forming limit of AISI 316LN stainless steel has been evaluated using the hemispherical punch forming test. The experimental forming limit diagram is compared with theoretical models of Swift, Hill and Sing Roo for validation. Sheet metal forming simulation was performed using the finite element software. The solution methodology was based on explicit time integration. A failure criterion has been introduced based on localized necking for the prediction of forming limit. The finite element predictions seem to be in good correlation with experimental results of AISI 316LN stainless steel. An error analysis on the FE-predictions was performed and the percentage deviation was found to vary between 0.28 and 12.24%. Theoretical models ore not predicting well with the experimental forming limit diagram.

Keywords

Hemispherical Punch Forming, Finite Element Simulation, Theoretical Model, Stainless Steel, Forming Limit Diagram.

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R. Rajendran ¹, S. Venkataswamy ¹, U. Jaikrishna ², N. Gowrishankar ², A. Rajadurai ³

Affiliations
1 Department of Mechanical Engineering, B.S.A. Crescent Engineering College, Chennai-600048, IN
2 IP Rings Ltd, D 11/12, Industrial Estate, Maraimalainagar-603209, IN
3 Department of Production Technology, Anna University, MIT Campus, Chennai-600044, IN

Abstract

Duplex coating is used in surface engineering to provide improved wear and corrosion resistance. The present study aims at hot dip aluminizing of a steel base followed by diffusion and nitriding treatments. The base material chosen for study is BS970 grade EN 8 steel (or 080M40). The specimens were dipped in molten aluminium-silicon alloy bath (11-13% Si) for various dip times (5-23 minutes) at 988K and diffused at 1173K for 8 hours. The diffused specimens were gas nitrided for 10 hours 50 minutes. The effect of dip time on coating thickness, diffusion layer thickness, microhardness and microstructure of aluminized, diffused and nitrided steel specimens were studied. The aluminium coating thickness does not significantly increase with the dip time beyond certain duration. The experimental studies indicate that the diffused layer thickness varies from 54-69 μm. The prolonged dipping time does not provide any significant advantage in increasing the diffused layer thickness. The surface hardness of EN 8 steel could he increased to about 800 HV when aluminized diffused and to about 1200 HV on subsequent nitriding. The increase in the hardness is attributed to the formation of hard nitride layer (Al-N). This methodology could be adopted for automotive and other engineering applications.

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P. Hariharan ¹, R. P. Chandrasekar ¹, A. Suresh Babu ¹, A. Rajadurai ², D. Mohanlal ³, S. Renganarayanan ³

Affiliations
1 Department of Manufacturing Engg., Anna University, Chennai-25, IN
2 Department of Production Technoiogy, MIT Campus, Anna University, Chennai-44, IN
3 Department of Mechanical Engineering, Anna University, Chennai-25, IN

Abstract

Bearing components should have high hardness accompanied by good wear resistance and load bearing strength. The most commonly used material for the manufacture of bearing components is steel. To achieve high hardness accompanied by good wear resistance, cryogenic treatment is considered as a supplementary process to conventional heat treatment. Increasing the wear resistance and the impact strength of the bearing components plays an important role in improving manufacturing standards. Since simultaneous enhancement of both these opposing properties is difficult in the heat treatment processes, a method of optimizing these properties together can increase the life o f the bearing components. The factors identified as affecting impact strength and wear resistance are the austenitising temperature, the austenitising time, the tempering temperature, the tempering time, the cryogenic treatment, the quenching media and the type of tempering. In this paper, an attempt is made to find out the optimum combination of heat treatment factors to optimize wear resistance and impact strength of the SAE 51100 bearing steel by using Taguchi’s techniques.

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