Article AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 218–223 Contents lists available at http://qu.edu.iq Al-Qadisiyah Journal for Engineering Sciences Journal homepage: http://qu.edu.iq/journaleng/index.php/JQES * Corresponding author. E-mail address: khalida.k.mansour @uotechnology.edu.iq (Khalida Kadhim Mansor) https://doi.org/10.30772/qjes.v15i4.854 2411-7773/© 2022 University of Al-Qadisiyah. All rights reserved. This work is licensed under a Creative Commons Attribution 4.0 International License. Numerical and experimental analyzes of forming parameters of low carbon steel Khalida Kadhim Mansor Department of Production Engineering & Metallurgy, University of Technology, Baghdad, Iraq A R T I C L E I N F O Article history: Received 2 October 2022 Received in revised form 20 Nov. 2022 Accepted 27 November 2022 Keywords: Deep Drawing Process coefficient of friction Die shoulder radius low carbon steel forming load A B S T R A C T Understanding sheet metal forming presses are important to reduce manufacturing costs. Thus, the best method of finding the optimum values of processing is by studying the effect of forming parameters on the behavior of formability, friction, and die radius. In this work, the deep drawing process of a low-carbon steel cup was studied and the significance of two important process parameters are investigated which are the friction coefficient and the radius of the die. The finite element method program, ANSYS, is used to study the effect of these parameters on forming load in the deep drawing process. The three levels of friction coefficient are considered which are 0.08, 0.00, and 0.15, and three die shoulder radius of 4, 6, and 8 mm. The results show that the predicted behavior of the punch load coincided well with both experimental and practical behaviors and the confidence is exceeding 94%. The wrinkling defect is happening when using a high die radius, Rd=8mm although the punch load is low due to the increase in the surface area on the edge of die. © 2022 University of Al-Qadisiyah. All rights reserved. 1. Introduction One of the most important manufacturing processes is the sheet metal forming which is considered is a cheap process when using in the mass production in industries application [1]. Deep drawing is used to manufacture a cylindrical cup with constant thickness distribution[2]. The initial shape of deep drawing blank is a flat circular blank which is set to form the cylindrical cup. Forming load was applied on blank by using punch and die to form the desired shape without folding the corners. a double action for punch force and blank holding force was applied at the same time on the blank to achieve the forming part. Deep Drawing can also be defined as the combined of compression and tensile deformation of a sheet to form a hollow body at the constant sheet thickness [3]. Below are details about the most importance parameters that effect of forming load in deep drawing process. 1.2 The effect of friction The most important variable in drawing process is the friction. The forming force, blank holder type, and blank holder force are depended on the friction value. The hollow bodies that are produced as a result of applying deep drawing process on metal blanks using die, punch, and blank holder, have http://qu.edu.iq/ mailto:Abdullah.F.Huayier@uotechnology.edu.iq https://doi.org/10.30772/qjes.v15i4.854 https://doi.org/10.30772/qjes.v15i4.854 http://creativecommons.org/licenses/by/4.0/ KHALIDA MANSOR /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 218–223 219 an impact the on selection of lubricant. Also, the friction type is a complex process in comparison to other processes due to the need f a low friction in sometimes, and also a high friction in other applications [4].importanttance parameters affectffect on friction is the selection of lubrication type as well as friction coefficient. 1.2.1 Lubrication effect The galling (pressure welding) between the die-blank and punch blank metal is happened in drawing process due to the sliding contact under pressure [5]. Drawing force increases when an extreme galling which occurs and unequal load distribution causes a fracture in the work piece. One of the most factors to prevent the failure such as wrinkling or tearing is the selection of the suitable lubricant during the deep drawing process as well as the ease of use and removal [6]. 1.2.2 Friction coefficient When using high value of friction coefficient, the wrinkling defect can be eliminated. However, in this case, the load distribution will be unequal, and consequently, this causes cracks and fracture in the material as shown in fig. 1,.The friction coefficient redound of (6.33%) of the total variance in the height of the drawn cup. The coefficient of friction increases with respect to the increase in the drawing cup height[7]. The risk of its wrinkling is occurred due to the tangential compression stress. This risk is likely occurred if there is a big difference between the initial blank diameter and the final diameter of forming cup and the sheet thickness is small [8].Yang, used the finite element method (FEM) to simulate the deep drawing process, and studied the strain distribution under different friction coefficients, and then applied the results in an experimental work and conducted a comparison between them [9]. Figure 1. Influence of the friction coefficient on the material’s damage[8] Liu Qiqian et. al. (2012) analyzed the process of microdot formation with a pillow using FEM that used to study the effect of the forming size and simulate the micro-forming process in multiple-points. The research aimed to study the effect of friction coefficient between materials on the surface finish and distribution of thickness of the final product from the center to the edge in the deformed plates[10]. 2. Objective The aim of the work is to show the: 1. Study of the effect of friction coefficient on punch load as well as the wrinkling defect. 2. The Effect of die radius on forming behavior and formability. 3. Theoretical consideration The important variables that affect the quality of the product are punching force (Fdr), the radiuses of die and punch (Rd, Rp), blank holding force (BHF), blank thickness (t), and the ratio of the draw which includes the ratio of the blank diameter to the punch diameter (D/d). In addition, material properties influence the product quality and cost in sheet metal forming process. Fig. 2 shows the deep drawing process geometric variables. Figure 2. Schematic the deep drawing process 3.1 The drawing force The work required to draw the blank into a cup is supplied by the punch force. The force exerted by the punch depending on the process parameter. The work required is a combination of pure deformation work and frictional work. The deformation work also depends on the fact that the forming mechanism is pure stretch forming, pure drawing or combination of both. A great many parameters are involved in determination of deformation work and consequently the punch force. Certain simplifying assumptions have to be made in order to determine an expression for maximum punch force [11]. This force can be estimated by following equation: 𝑭𝒅𝒓 = 𝝅 ∗ 𝒅 ∗ 𝒕 ∗ 𝝈𝒖 ∗ (𝜷 − 𝑮) (1) Where: Fdr= drawing force σu = ultimate tensile stress G = constant (0.6 – 0.7) to cover bending and friction It was observed that by varying the metal volume and metal resistance, the punch force will be increased and reaches to the maximum value, and after that top point, it been gradually decreases to zero. The maximum value of drawing force occurred when the punch depth is equal to (Rp+Rd), or at value around (0.333) of the punch stroke length [12]. 3.2 The influence of friction 220 KHALIDA MANSOR /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 218–223 When the friction between blank and punch increases, it can be seen that the material flows from underneath the punch bottom over the punch nose. The high friction coefficient will prevent the flow of material over the punch nose, which in turn will prevent excessive stretching of the sheet metal at the bottom of the punch, and consequently increases the limit drawing ratio (LDR). The high friction coefficient between die and sheet will decrease the LDR. Existing the friction over the die corner radius and in the flange, causes a difficulty in drawing of the sheet metal. It will increase the required punch force. This situation will cause excessive stretching and a fracture in the unsupported regions. Fig. 3 shows the coefficient of friction increases when the limiting drawing ratio (LDR) was decreases [13]. Figure 3. Relation between friction coefficient and LDR [13] The friction resistance stresses (𝜏ƒ) for flat surface is a result of multiplying of the friction coefficient (μ), and the blank holder pressure (P), as illustrated by the following equation: τf = μ ∗ p …(2) And, for the inclined surface has an angle (α): τf = μ ∗ p ∗ cos⁡(α) …(3) 3.3 The influence of die profile radius: Die radius (Rd) depends on the workpiece size and thickness, and large radius of die is required to use in order to increase the limit drawing ratio and also to reduce the drawing load. However, there is a decrease in the contact area between the empty holders at using of large die radius. Additionally, there is an increase in the probability of occurrence of the wrinkles [14]. 4. Numerical simulation FEM was used to analyze the forming process under the specified working conditions that entered by the users. The users are changing and repeating the conditions and conducting the analysis until they find the suitable conditions that reduce the efforts of the users in numerical simulation, which used to: • Predicting the material flow during the particular process (on the draw beads in deep drawing). • Predicting the punch force, blank holder force and the stresses that are necessary to execute the forming process. • Prevent the failure which could be caused by the defect in die- punch design. In this work the commercial finite element package (ANSYS 14) is used to simulate the process of draw bead in deep drawing process for cup forming. The numerical results have compared with the experimental results. The punch, die and the blank holder represented by (Target 169), which defined by three nodes, and each node has two degrees of freedom. The blank material represented by (Visco 106), which defined by four nodes, and each node has up to three degrees of freedom. The contact interface between die and the deformed material is represented by (Contact 171), which has two degrees of freedom at each node. The loading was conducted in the form of a prescribed displacement. The isotropic hardening plasticity model have been used. As the driving force to obtain plastic response, the Von Mises stress has been applied to compute by the most commercial FEM package as illustrated in fig .4. Figure 4. Simulation of present work using ANSYS (14) program The result of deep drawing analysis was illustrated in table 1. with different coefficient of friction and their effect on punch load variations when the die radius is 4. And after that, a numerical simulation was performed to investigate the effect of die radius on deep drawing process. Different simulations with two die radius; 6 & 8, and at different coefficient of friction; 0.08, 0.1, and 0.15 were performed. Table 1. illustrated the result using finite element at different coefficient of friction (Rd=4mm) µ=0.15 without lubrication µ=0.1 using wax µ =0.08 with graphite and grease Punch stroke Punch load Punch stroke Punch load Punch stroke Punch load 0 0 0 0 0 0 0.9854 1.235 1.0752 1.165 1.0102 0.9025 3.0124 5.364 2.2542 5.231 2.9956 3.365 5.9854 10.089 6.3674 9.9806 6.1202 7.5326 9.1235 20.147 9.3275 18.0123 9.2235 15.6541 11.9852 22.457 13.533 20.4561 13.0125 18.9541 KHALIDA MANSOR /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 218–223 221 14.9582 26.4971 15.5451 23.2564 15.212 23.4587 16.3652 28.9522 18.1106 26.4589 18.125 25.6871 18.5682 31.512 20.1204 30.2101 19.2669 28.3654 19.6985 32.3425 22.9841 31.123 20.2365 29.5841 22.8562 32.0143 24.721 30.952 23.256 25.3641 24.2658 30.478 26.0985 29.7841 25.2365 21.0124 25.9856 27.1438 26.2854 25.142 26.321 19.2541 28.0125 18.42 28.1235 17.5421 28.0112 15.2364 28.9985 15.0954 29.1024 14.4536 29.1145 11.131 31.3254 12.3246 31.5012 11.4581 31.3956 9.5471 5. Experimental work After applied the finite element analysis with appropriate forming condition and used this result in experimental work. The experimental work conducted using INSTRON universal testing machine which has a force capacity 180 KN and speed of the testing was kept constant at 10 mm/min. The forming blank has 80 mm a diameter, 0.5 mm thickness, and made from low carbon steel (1006–AISI) of the following mechanical composition is listed in table 2. A typical cylindrical cup drawing process was chosen for detailed analysis in deep drawing process with draw beads that presented in fig. 5. The cup (40 mm) outer diameter with die profile radius (Rd=4, 6 and 8) and punch diameter (38.8mm) with corner radius (Rp=2mm) was used to completely drawn the die that shown in fig 6. Table 2. low carbon steel mechanical properties (1006–AISI) Property Value Young modulus (Gpa) 200 Position ratio 0.3 yield stress (MPa) 125 tangent Modulus (GPa) 0.52 The experimental result of deep drawing process was illustrated in table 3. with different coefficient of friction and their effects on the punch load variations when using die radius (Rd=4). Following, the experimental work was conducted with die radius (Rd=6) and die radius (Rd=8) and the coefficient of friction varies from a low of 0.05 to 0.2. Figure 5. Experimental setting of deep drawing process Figure 6. Samples of completely drawn cup Table 3. illustrated the result of experimental work at the different coefficient of friction (Rd=4mm) µ=0.15 without lubrication µ=0.1 using wax µ =0.08 with graphite and grease Punch stroke Punch load Punch stroke Punch load Punch stroke Punch load 0 0 0 0 0 0 1.121 1.14 0.998 1.012 1.002 0.958 2.312 3.985 2.341 3.457 2.262 3.12 6.21 7.214 6.187 7.101 6.214 7.011 9.241 11.561 9.365 10.452 9.353 10.124 13.501 13.985 12.785 12.875 12.675 12.231 15.212 17.567 15.321 16.245 14.985 15.998 18.21 19.587 18.01 17.895 18.142 17.745 20.31 21.542 19.998 20.154 19.874 19.895 22.695 25.654 22.11 24.652 22.562 23.997 24.575 29.584 24.352 28.245 24.152 27.254 26.213 31.524 26.114 29.587 26.241 28.114 26.562 33.254 26.568 31.251 26.415 29.245 28.141 30.241 28.21 29.584 28.325 28.114 29.256 24.251 29.14 23.154 29.354 21.457 31.378 18.354 31.375 16.254 31.241 14.654 6. Results and discussions Variation of the friction coefficient, the die radius in nine different cylinder shapes (3x3) is considered to study their effect on the forming process behavior, in particular the punch load. Fig. 7 illustrated the relationship between the punch load and the punch stroke in simulation and experimental works. While, fig. 8 presents the confidence between the punch load in numerical and experimentally at different values of coefficient of friction. It has seen from the figure for µ=0.15 (without lubrication), the required forming load is 33.254 KN. While for experiment under coefficient of friction 0.08, radius equal to 6 mm, and the lubricant is grease, the forming force is down to 28.998 KN and there is no difference in the simulation and experimental results under the same conditions of coefficients of friction. wrinkling defect occurs when the applied punch load is at lower level and coefficients of friction 0.08 accompanying with using graphite and grease as a lubricant. 222 KHALIDA MANSOR /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 218–223 Figure 7. The relation between punch stroke and punch load, (A) Simulation, (B) Experimental Figure 8. Confidence between FEM and EXP. with different parameters. 7. Conclusions 1. Finite element method was used to simulate the forming process of a cylindrical shape and the result has been compared to experimental work with different values of parameters (coefficient of friction and die radius). 2. From the results shown in figures (7), the predicted behavior of forming process was clearly indicated that the punch load with coincided well with A A A B B B 92 94 96 98 100 0.150.10.08 C o n fi d e n ce % coefficient of friction r=6mm r=4mm r=8mm KHALIDA MANSOR /AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 218–223 223 both analytical and experimental behaviors and the overall deviation are not exceeding 6%. 3. The effect of two die geometry parameters: die radius and coefficient of friction, on the load forming distribution were studied by simulation and experimental work. The results showed when the coefficient of friction increases and die radius decreases, the forming force will be increased. 4. From the results, they show that using high die radius (Rd=8) with applying low force punch, is a main reason for occurring of wrinkling defect. REFERENCES [1] Tahir Altinbalik, Aysun Tonka, Numerical and expermintal study of sheet thickness variation in deep drawing processes, International Journal of Modern Manufacturing Technologies ISSN 2067–3604, Vol. IV, No. 2 / 2012 [2] A.D.Younis, The effect of drawing ratio in deep drawing process on thickness distribution along the cup, Al-Rafidain Engineering Vol.18 No.4 August 2010 [3] D.Swapna, Ch.Srinivasa Rao, S.Radhika, B.RaviRaja, DEEP DRAWING PROCESS: A BRIEF OVERVIEW, NCAMMS 2015 [4] Ter verkrijging van: “Modelling of contact and friction in deep drawing Processes”; Printed by FEBO druk B.V., Enschede; Printed by FEBO druk B.V., Enschede [5] Nayan Kaneriya, Darshan Shah, Rishit Rana, Vaishal Shah, Parth Thakkar, Effect of Different Parameters on Deep Drawing Process for Minimum Stress and Defects by Experimental and Simulation Study: A Review, International Journal of Advance Engineering and Research Development Volume 3, Issue 10, October -2016 [6] A. R. JOSHI, K. D. KOTHARI, Dr. R. L. JHALA, Effects Of Different Parameters On Deep Drawing Process: Review, International Journal of Engineering Research & Technology (IJERT) Vol. 2 Issue 3, March – 2013 [7] A. Chennakesava Reddy “Parametric Significance of Warm Drawing Process for 2024T4 Aluminum Alloy through FEA”, International Journal of Science and Research, vol. 4, no. 4, pp. 2345-2351, 2015. [8] Devendar.G, A. Chennakesava Reddy, Study on Deep Drawing Process Parameters - A Review, International Journal of Scientific & Engineering Research, Volume 7, Issue 6, June-2016 ISSN 2229-5518 [9] T.S. Yang “Investigation of the Strain Distribution with Lubrication During the Deep Drawing Process”, Tribology International, vol. 43, pp 1104– 1112, 2010. [10] Liu Qiqian, Lu Cheng, Fu Wenzhi, Tieu Kiet, Li Mingzhe, Gong Xuepeng “Optimization of Cushion Conditions in Micro Multi-Point Sheet Forming” [11] Vukota Boljanovic "Sheet Metal Forming Processes and Die Design" ISBN 0-83 1 1-3 182-9 (2004). [12] Kakandikar G.M. "Optimization of forming load and variables in deep drawing process for automotive cup using Genetic Algorithm " Prentice Hall of India Private Limited, New Delhi, pp 1-4, (2008) [13] J. A. Schey, “Introduction To Manufacturing Process”, third edition, Mc Graw-Hill series in mechanical engineering an material science, ISBN 0- 07- 0311, (2000). [14] D. E. Ostergaard “Advanced Die making”, McGraw-Hill Book Company,(1967). [15] Jalil Jabbar Shukur, Effect of Blank Holder Types on Drawing of Mild Steel Round Cup with Flange, University of Technology,2013