This paper focuses on the effect of the die and punch radii on the springback in the air V-die free bending process of stainless steel sheet metal. The experiment was performed on sheet metal using various die and punch radius values while their springback behavior was observed. The design of experiment approach was used in these experiments using the full factorial and analysis of variance methods to identify whether or not the die and punch radii are significant input parameters in predicting springback. From the statistical analysis, it shows that the die and punch radius parameters are significant factors contributing to the springback effect in the V-die bending of stainless steel sheet metal at the significance level of 0.05 because their p value is less than 0.05. The results from the experiments showed that springback is affected by the die and punch radius values in the air V-bending experiments. From this analysis, it can be concluded that the springback values can be decreased by decreasing the values of the die and punch radii. In the air V-die bending process, the punch radius is the most important factor to be considered. The experimental method agreed well with the design of experiment results.

Advanced High Strength Steels (AHSS) are increasingly utilized especially in automotive industry. However, forming of AHSS is challenging particularly in prediction of springback effect caused by material properties, tools and dies parameters, work material and bending technique factors. An air V-bending process was chosen as an evaluation problem because it showed larger springback effect. This paper presents an optimization to predict the influence of various parameters on springback of sheet metal in air V-bending process using Taguchi method (TM). The experimental study was conducted on DP590 sheets with plate thickness of 1 and 2 mm under different process parameters such as punch radius, die radius, die gap and punch travel. A significant level of springback parameters was further described by using the analysis of variance (ANOVA). It showed that the contribution percentage of each factor to springback was calculated to optimum level and the significant levels of entire factor were observed. The thickness of material, die width, punch travel and punch radius were found to be the most significant factor affecting springback while die radius is insignificant.

Springback is a serious problem for the manufacturing industry due to error in the appearance of the final product especially in bending process. Therefore, it's important to investigate the factors that affect the springback behavior . This paper focused on the effect of two parameters, namely die gap and punch travel on springback behavior in air V-die bending process for stainless steel sheet metal. Different values of die gap and punch travel were experimentally used and the final bent angle was measured. Design of Experiments (DoE) was based on Taguchi Method (TM) and the optimum parameters was obtained using signal-to-noise (S/N) ratio. Further analyzed, Analysis of Variance (ANOVA) techniques was carried out to investigate which of the factors are significance on springback effect. The result show that punch travel is the most significance factor than die gap factor based on p-value for punch travel and die gap were 0.003 and 0.045, respectively. From this two factors, punch travel is most considered to reduce springback phenomenon compared to die gap and the effect could be improved through modification of this parameter.

The use of advanced high strength steels as a metal in sheet metal forming in automotive industry currently has been increased where Advanced High Strength Steel (AHSS) especially Dual Phase (DP590) Steels have gained a great attention due to a combination of high strength and good formability. However, one of the major constraints in forming AHSS is the occurrence of high spring back caused by elastic relaxation after loading, which causes illness-fitting in part assembly and geometric deviation of the intended design. Spring back is the main problem of defect that occurs at sheet metal after the bending process which creates problems for the parts during the assembly. This paper presents an investigation the effect of spring back on bending test of Dual Phase Steel (DP590). Punch travel and thickness are among factors affecting the spring back behavior. Various parameter value; punch radius (5mm), die radius (5mm), die gap (70mm), thickness of specimen 1mm and 2mm, punch travel/stroke (25%, 50%, 75%, 100%) from 20 mm depth, punch speed (2mm/min) and Orientation of sheet cutting, which is in rolling (00°), diagonal (45°) and transverse (90°). From the analysis of V-bending test punch travel, thickness and orientation of sheet cutting are significant factor that affecting the spring back phenomena. The result form this experiment could be useful for design engineers and manufacturing engineers to make improvement of predict the spring back behavior and also to understanding the material properties of AHSS in order to eliminate spring back and achieve good final product.

Springback is a serious problem in the manufacturing industry due to errors that effects the appearance of the final product especially in the sheet forming process. This paper presents the review on past literature regarding factors that affects the amount of springback that occurs after the forming operation. This paper focus on 5 major elements that affects the value of springback including yield stress (σy), Young’s modulus (E), strain hardening exponent (n), Poisson’s Ratio (v) and thickness of the sheet (t). This 5 elements show that, increases in the value of (σy), (n), will increase the value of springback. The springback decreases with increasing of (t) and (E). While (v) has a small significant effect on springback. The effects of these factors can be used as a guide when considering further research on springback.