Papers by Author: Surasak Suranuntchai

Abstract: The forming limit curve (FLC) is commonly used to predict the formability behavior of sheet metal after the forming process. In this research, the forming limit curve generated from the Materials Model was applied to analyze and predict the fracture behavior of the fuel tank workpiece, a motorcycle part made of AA5754-O material, using the deep drawing process simulated by the finite element method. The research involved a comparison with actual cracks that occur in the automotive industry after molding. To determine the mechanical properties of the AA5754-O material for use in the forming limit curve, a specimen with a thickness of 1.5 mm was subjected to a tensile strength test, providing the necessary input for the mechanical properties in the forming limit curve based on the Keeler-Beizer equation. The forming limit curve is a correlation graph between major strain and minor strain. When the FLC is created from the Materials Model, it is utilized in conjunction with deep drawing drag simulation in the PAM-STAMP program to predict the fracture point. The accuracy of the mathematically generated FLC in predicting fracture behavior was verified after the deep drawing process. The study found that the FLC based on the Keeler-Beizer equation can accurately predict the cracking behavior of AA5754-O sheet metal, enabling identification of the fracture location during the deep drawing process. One advantage of creating the FLC from the material models is its compatibility with the same material but with different workpiece shapes, allowing its use in conjunction with molding simulations using various programs. This approach saves costs associated with testing to obtain the FLC.

Abstract: This study investigates the impact of lubrication on friction factors during the hot ring compression test of BS 080M46 medium carbon steel. Hot forging processes are crucial in industries due to the strength and durability of forged products, but friction-related issues can arise. Four lubrication conditions are focused: dry, oil to black graphite, water to black graphite, and water to colorless graphite. The ring compression test procedure, including sample dimensions and lubrication application, is explained. By employing predictive calibration curves generated through FEM which monitored height and internal diameter changes during compression. The study successfully aligns FEM simulation results with experimental data, thereby enhancing the accuracy of friction factor estimations and visualizing material behavior under various lubrication conditions. Results indicate that lubrication significantly affects friction factors, with oil to black graphite performing the best, yielding a friction factor of 0.15. A comparison between theoretical and experimental friction factors shows varying agreement levels, with water-to-black graphite, and water-to-colorless graphite respectively demonstrating excellent alignment with 0.990% and 0.971%. This study has practical implications for selecting lubricants in industrial applications, potentially enhancing manufacturing processes and product quality.

Abstract: Deep drawing process is a common sheet metal forming technique in motor vehicle manufacturing. There are three primary defects that could be occur in deep-drawn parts: tearing, wrinkling, and thinning. When the thinning is difficulty detected by visual inspection. As a result, this study aims to address the thinning issue in a fuel tank part made from an aluminum alloy sheet AA5754-O 1.5 mm thick under cold working deep drawing process, while the manufacturer's desired upper limit for thinning is 20%. Two influential parameters viz. blank holder force and initial size of blank, were investigated and optimized by using Finite Element Analysis (FEA) through PAM-STAMP simulation software with the validated material model was based on Hill’s 1948 anisotropic yield criterion with Swift hardening law. The mechanical parameters in the mentioned model were derived from the results of uniaxial tensile tests. In conclusion, both the hydraulic cushion's blank holder pressure and the initial size of the blank were found to influence the thinning of the part, either individually or in combination. Despite optimizing both parameters, they were unable to consistently achieve the desired limit.

Abstract: Three-dimensional finite element modeling (FEM) has been carried out using QForm software on the hot forging operation of the upper ball joint, involving the process of roughing and finishing. The material used is SNCM8 commercial alloy steel. This paper aims to optimize the initial billet size to achieve a final forged product without any defects. To accomplish this task, it was necessary to determine the initial optimum billet size by calculating the mass ratio. It is more practical to reduce the length of the initial billet and keep the diameter constant. The initial billet size was obtained by FE simulation by varying the five cases of mass ratio. The minimum dimension of the initial billet, which filled the die cavity without defects, was selected for the tryout experiments. The experimental results supported the FEM results and indicated that the optimum size was ∅48x152.88 mm, which may reduce material waste by 17.65%. Additionally, the forging load during the forging process was investigated. The actual forging load was slightly higher than the experimental one. The forging load showed a maximum error about 10.13%. Finite element simulation by QForm V10.1.6. software is recommended as an efficient tool for predicting the hot deformation behavior of the material during several stages of hot forging, which can save material costs and the cost of trials, leading to enhancements in the manufacturing process.

Abstract: This paper presented an analysis of the two-step of hot forging process are carried out to manufacture Upper Ball joint, which are including roughing and finishing operation. The part was made from SNCM8 alloy steel. The simulation has been done with application of QForm V10.1.6 software. The constitutive model based on Zener-Hollomon parameter was applied. As a result of simulations, metal flow lines, plastic strain, temperature distribution and effective stress for forgings were obtained. Finite element simulation by QForm V10.1.6. software is suggested as a valuable tool for predicting the hot deformation behavior of material during multi-stage of hot forging process which utilized to enhance the manufacturing process. In addition, the forming load and thickness during the forging process were analyzed. It was found that the deviation of forming load between simulation and experiment was raised to 10.71% and the maximum error of flank thickness was 5.137%. within specification. Therefore, the workpieces of the quality required by specification are obtained.

Abstract: Finite Element Method (FEM) becomes one of the most useful techniques to analyze problems in sheet metal forming processes because of this technique can reduce cost and time in die design and trial step [1]. This research was aimed to predict the optimal parameters in order to eliminate cracks and wrinkles on stainless steel sink product under deep drawing named “DLS50”. The material was made from Stainless Steel 304 with thickness 0.6 mm. The parameters that had been investigated were punch angle and velocity as well as pressure of the punch. In order to simplify the process, punch and die in the simulation were assumed to be a rigid body, which neglected the small effect of elastic deformation. The properties of stainless steel sheet was assumed to be anisotropic, behaved according to constitutive equation of power law and deformed elastic-viscoplastic, which followed Barlat 3 components yield function. The deformation for Forming Limit Diagram (FLD) was predicted by the Keeler equation. Most of the defects such as cracks and wrinkles were found during the process on the parts. In the past, practical productions were performed by trial and error, which involved high production cost, long lead time, and wasted materials. From the prediction results, decreasing punch velocity from 50 mm/s to 8.33 mm/s would reduce the blank shearing zone on the corner bottom of the part and remove cracks in the process. The performing of the stainless sink by decreasing pressure in the process from 2.3 bar to 2 bar, and adjusting the punch shape increasing 5 mm. each side would increase formability of sheet metal in all direction, the reduction of cracking tendency zone out of the part. In conclusion by using the simulation technique, the production quality and performance had been improved.

Abstract: The manufacturing industries for automotive parts aim to develop technologies for reducing vehicle weight in order to decrease fuel consumption. However, passive safety function for drivers and passengers must not be impaired or should be even improved. Therefore, advanced high strength steel sheet plays more and more important role in designing automotive components. Nowadays, prediction of formability for sheet metal stamping has high capability more than the past. The major challenge is springback prediction. Moreover, it assists in the tooling design to correctly compensate for springback. Especially in automotive production, springback effects have been generally exhibited distinct after forming process of the high strength steel sheets. The springback effect occurred in the deformed state of metal parts must be taken into account by designing any sheet metal panels. Then, the purpose of the present research is to investigate the springback phenomenon of an automotive part named Reinforcement Rocker RL made from an advanced high strength steel grade JAC780Y, after stamping. In addition, the tools design has been carried out. Finite Element (FE) program known as DYNAFORM (based on LS-DYNA solver), has been applied to analyze and improve the springback effect on such forming part. An anisotropic material model according to type 36 (MAT_036 3-PARAMETER_BARAT) was applied. The results obtained from simulations were compared with required parts in each section. Then, the die surface from compensation in 2nd step forming was modified to use. Finally, the simulation part was verified with the real stamping part. It was found that the finite element simulation showed high capability for prediction and compensation of springback in high strength steel sheets forming.

Abstract: Finite Element Method (FEM) is one of the most popular methods in the automotive industry to reduce problems, time and wastes in production processes. This method can predict the metal forming processes with computer modeling before making forming tools. In sheet metal forming analysis, Forming Limit Diagram (FLD) is one of the most important indicators in FEM, it can tell each forming regions such as cracks, wrinkles and safe zone. However, the FLD that has automatically created in finite element program isn’t enough accurate. Then, the main objective of this research work was to generate FLD of the ultra-high strength steel: NSC980D that usually has been used in auto body frame by using Nakajima's tests. Then, the generated FLD was used to simulate the forming of the automotive parts for solving the cracks caused during the forming along with the Hill’s 1948 material model. The Keeler’s FLD, which is generated automatically by the commercial software applied, was plotted for comparison during simulation, as well. Drawing process of the panel front was investigated by applying FEM simulating tool: PAMSTAMP to analyze the formability and to determine the optimal forming parameters under suitable service conditions. The main parameters of interest were the part and blank configuration. A number of corrections were successively made to successfully form the part. From the analysis of 2 case studies, it was found that tearing was occurred in the first case results. When the forming force was reduced from 15 tons to 9 tons in the second case, the complete forming without tearing and similar like actual forming at the same conditions had been taken place in the second results.

Abstract: In this study, the forging operations of gear has been modeled. This gear is a part which is manufactured with the help of hot forging industry for reduce the cost. The authors propose to reduce the initial billet volume of AISI 4340 steel for the forged through process optimization using the Finite Element (FE)method. The object of this research was to predict the effect of several parameters, such as effective stress, effective plastic strain, temperature and die contact, on the forming of the gear, utilizing computer simulation and experimental results. For this purpose, Solidworks CAD and Simufact Forming FE software were used for the modeling and analysis of the forging process. The billet volume and the preform design were predefined in order to reduce scrap by using preform type C. The experimental results showed that the initial billet volume was reduced at 32 %, which compared favorably with the simulation result of a 40 % reduction. The maximum preforming force of simulation result was diferent with the experiment result at 18 along with the maximum finishing force of simulation result was different with the experiment result at 11 %. It was also found that the effective stress decreased with increasing the temperature, and the press force decreased when the initial billet volume was decreased, which resulted in a decrease of effective plastic strain as well.

Abstract: Finite Element Method (FEM) is one of the most useful techniques to analyze problems in metal forming process because of this technique can reduce cost and time in die design and trial step [1]. This research is aimed to predict the optimal parameters in order to eliminate cracks and wrinkles on automotive deep drawing product “Shell Bar RR Impact RH/LH”. The material was made from high strength steel JSC440W sheet with thickness 1.8 mm. The parameters that had been investigated were blank holder force (BHF) and drawbead restraining force (DBRF). In order to simplify the process, punch and die in the simulation were assumed to be a rigid body, which neglected the small effect of elastic deformation. The material properties assumed to be anisotropic, behaved according to the constitutive equation of power law and deformed elastic-viscoplastic, which followed Barlat 3 components yield function. Most of the defects such as cracks and wrinkles were found during the processes on the parts. In the past, the practical productions were performed by trial and error, which involved high production cost, long lead time and wasted materials. From the results, when decreased blank holder force to 30 tons, cracks on the part were removed but wrinkles had a tendency to increase in part area because of this part is the asymmetrical shape. Finally, applying about drawbead restraining force at 154.49 and 99.75 N/mm could improve product quality. In conclusion, by using the simulation technique, the production quality and performance had been improved.