Formability and Surface Finish Studies in Single Point Incremental Forming

Author(s):  
A. Bhattacharya ◽  
K. Maneesh ◽  
N. Venkata Reddy ◽  
Jian Cao

Incremental sheet metal forming (ISMF) has demonstrated its great potential to form complex three-dimensional parts without using a component specific tooling. The die-less nature in incremental forming provides a competitive alternative for economically and effectively fabricating low-volume functional sheet parts. However, ISMF has limitations with respect to maximum formable wall angle, geometrical accuracy, and surface finish of the component. In the present work, an experimental study is carried out to study the effect of incremental sheet metal forming process variables on maximum formable angle and surface finish. Box–Behnken method is used to design the experiments for formability study and full factorial method is used for surface finish study. Analysis of experimental results indicates that formability in incremental forming decreases with increase in tool diameter. Formable angle first increases and then decreases with incremental depth and it is also observed that the variation in the formable angle is not significant in the range of incremental depths considered to produce good surface finishes during the present study. A simple analysis model is used to estimate the stress values during incremental sheet metal forming assuming that the deformation occurs predominantly under plane strain condition. A stress-based criterion is used along with the above mentioned analysis to predict the formability in ISMF and its predictions are in very good agreement with the experimental results. Surface roughness decreases with increase in tool diameter for all incremental depths. Surface roughness increases first with increase in incremental depth up to certain angle and then decreases. Surface roughness value decreases with increase in wall angle.

Author(s):  
A. Bhattacharya ◽  
Samarjit Singh ◽  
K. Maneesh ◽  
N. Venkata Reddy ◽  
Jian Cao

Incremental sheet metal forming (ISMF) has demonstrated its great potential to form complex three-dimensional parts without using a component specific tooling. The die-less nature in incremental forming provides a competitive alternative for economically and effectively fabricating low-volume functional sheet parts. However, ISMF has limitations with respect to maximum formable wall angle, geometrical accuracy and surface finish of the component. In the present work, an experimental study is carried out to study the effect of incremental sheet metal forming process variables on maximum formable angle and surface finish. Box-Behnken method is used to design the experiments for formability study and full factorial method is used for surface finish study. Analysis of experimental results indicates that formability in incremental forming decreases with increase in tool diameter. Formable angle first increases and then decreases with incremental depth and it is also observed that the variation in the formable angle is not significant in the range of incremental depths considered to produce good surface finishes during the present study. A simple analysis model is used to estimate the stress values during incremental sheet metal forming assuming that the deformation occurs predominantly under plane strain condition. A stress based criterion is used along with the above mentioned analysis to predict the formability in ISMF and its predictions are in very good agreement with the experimental results. Surface roughness decreases with increase in tool diameter for all incremental depths. Surface roughness increases first with increase in incremental depth up to certain angle and then decreases. Surface roughness value decreases with increase in wall angle.


Author(s):  
Ramkumar Kathalingam ◽  
Baskar Neelakandan ◽  
Elangovan Krishnan ◽  
Sathiya Narayanan Chinnayan ◽  
Selvarajan Arangulavan ◽  
...  

Incremental Sheet metal Forming (ISF) is a reliable process of converting a blank to work piece with better outputs compared to conventional forming process. The flexibility of ISF in producing the rapid prototype based on the customer needs is increased which is also desirable in the industry. But Single Point Incremental Forming (SPIF) process takes more time to form a product and hence the longer time is a barrier in implementing this process in industries. In this research work, the ISF process was made on sheet metal SS 202 using a newly designed multi-point tool and the obtained outputs were compared with the same material of sheet metal formed by traditionally available single point tool. This Multi Point Incremental Forming (MPIF) process takes lesser process time to give better formability, improved wall angle and good surface roughness. The input process parameters selected for the process are type of tool, speed, feed, Vertical Step Depth (VSD), and lubrication. They are arranged by using the taguchi Design of Experiments (DOE) approach. The responses considered are wall angle, formability, surface roughness, spring back and forming time. The multiple outputs obtained were optimized by Grey Relational Analysis (GRA) to predict the superior parameter. Confirmation test was also made to validate the output result. Fractography analysis was carried out to predict the fracture mechanism obtained during the forming process. The surface topography was also made on the surface of the formed area of the sheet metal. This research work concludes that newly designed MPIF outperforms SPIF.


2019 ◽  
Vol 13 (2) ◽  
pp. 4911-4927
Author(s):  
Swagatika Mohanty ◽  
Srinivasa Prakash Regalla ◽  
Yendluri Venkata Daseswara Rao

Product quality and production time are critical constraints in sheet metal forming. These are normally measured in terms of surface roughness and forming time, respectively. Incremental sheet metal forming is considered as most suitable for small batch production specifically because it is a die-less manufacturing process and needs only a simple generic fixture. The surface roughness and forming time depend on several process parameters, among which the wall angle, step depth, feed rate, sheet thickness, and spindle speed have a greater impact on forming time and surface roughness. In the present work, the effect of step depth, feed rate and wall angle on the surface roughness and forming time have been investigated for constant 1.2 mm thick Al-1100 sheet and at a constant spindle speed of 1300 rpm. Since the variable effects of these parameters necessitate multi-objective optimization, the Taguchi L9 orthogonal array has been used to plan the experiments and the significance of parameters and their interactions have been determined using analysis of variance (ANOVA) technique. The optimum response has been brought out using response surfaces. Finally, the findings of response surface method have been validated by conducting additional experiments at the intermediate values of the parameters and these results were found to be in agreement with the predictions of Taguchi method and response surface method.


2013 ◽  
Vol 753-755 ◽  
pp. 203-206 ◽  
Author(s):  
On Uma Lasunon

This paper presents the effect of forming parameters on the arithmetic mean surface roughness (Ra) of aluminum alloy built by a single-point incremental sheet metal forming process. Three investigated parameters are feed rate (12.5, 25 and 50 in/min), depth increment (0.015 and 0.030 in), and wall angle (45° and 60°). The results show that wall angle, depth increment and its interaction play an important role on the surface roughness, while feed rate has little effect. The optimal forming conditions for minimum surface roughness are feed rate of 25 in/min, depth increment of 0.015 in and wall angle of 45°.


Incremental Sheet metal forming is a die less method of forming which offers high formability. In this research work; effect of step depth, tool rotation speed and preheating temperature on surface roughness and thinning of flange wall is investigated in hole flanging using incremental forming. The parameter optimization is carried out by Taguchi method. Grey relational analysis is carried out to obtain best parameter combination.


2011 ◽  
Vol 308-310 ◽  
pp. 1004-1007
Author(s):  
Liu Ru Zhou ◽  
Hai Ming Wan

The principle of NC incremental sheet metal forming as well as the process planning, experiment of the square conical box forming are presented. Because the deformation of sheet metal only occurs around the tool head and the deformed region is subjected to stretch deformation and thins, and surface area increases. Sheet metal forming stepwise is to lead to the whole sheet metal deformation. The sine law indicates that the thickness of the square conical box wall is close to zero when the half-apex angle of the square conical box wall is close to zero. Therefore, we must know the forming limit half-apex angle to ensure that the forming can be carried out successfully, i.e., to ensure that the deformed region with a certain thickness will not fracture. It will succeed in square conical box incremental forming in a single tool-path if the forming is carried out with an angle which is larger than the forming limit half-apex angle. The fracture in the forming component can be avoided by these methods. A square conical box of uniform wall-thickness can be formed by NC incremental forming process. The thickness of deformation area is increased by increasing half-apex angle. The wrinkle in the forming component can be avoided by these methods.


2012 ◽  
Vol 729 ◽  
pp. 85-90 ◽  
Author(s):  
Miklos Tisza ◽  
Péter Zoltán Kovács ◽  
Zsolt Lukács

The need for flexible forming processes is of utmost importance in the recent years. Therefore, it is very important to develop new innovative technologies and processes. This is particularly valid for small batch and prototype production. Incremental sheet metal forming may be regarded as one of the promising developments for these purposes. In this paper, first a general overview of main process characteristics of the incremental sheet metal forming will be given. Then some recent results of a joint Eureka project launched by two universities and two SME companies in Hungary and Slovenia will be presented.


Author(s):  
Rakesh Lingam ◽  
Anirban Bhattacharya ◽  
Javed Asghar ◽  
N. Venkata Reddy

Incremental Sheet Metal Forming (ISMF) is a flexible sheet metal forming process that enables forming of complex three dimensional components by successive local deformations without using component specific tooling. ISMF is also regarded as die-less manufacturing process and in the absence of part-specific dies, geometric accuracy of formed components is inferior to that of their conventional counterparts. In Single Point Incremental Forming (SPIF), the simplest variant of ISMF, bending near component opening region is unavoidable due to lack of support. The bending in the component opening region can be reduced to a larger extent by another variant of ISMF namely Double Sided Incremental Forming (DSIF) in which a moving tool is used to support the sheet locally at the deformation zone. However the overall geometry of formed components still has unacceptable deviation from the desired geometry. Experimental observation and literature indicates that the supporting tool loses contact with the sheet after forming certain depth. Present work demonstrates a methodology to enhance geometric accuracy of formed components by compensating for tool and sheet deflection due to forming forces. Forming forces necessary to predict compensations are obtained using force equilibrium method along with thickness calculation methodology developed using overlap that occurs during forming (instead of using sine law). Results indicate that there is significant improvement in accuracy of the components produced using compensated tool paths.


2011 ◽  
Vol 473 ◽  
pp. 889-896 ◽  
Author(s):  
D. Kreimeier ◽  
J. Zhu ◽  
V. Smukala ◽  
B. Buff ◽  
C. Magnus

Robot based incremental sheet metal forming (Roboforming)is a new dieless forming process, which is suitable for cost-effective manufacture of prototype parts and small batch sizes.The principle of Roboforming is based on flexible shaping through a freely programmable path-synchronous movement of two industrial robots. These two robots, which are connected to a cooperating robot system, hold respectively a forming and a supporting tool. Similar to other incremental forming methods, the final shape is produced bythe movement of the forming toolalongthe lateral direction and its gradual infeed in the depth direction. In Roboforming, there are twodifferent strategies for the synchronous movement of the supporting tool, eitheralong the outer contour onbacksideof the sheet or directly opposed to the forming tool building a forming gap.The second strategy can be combined with a force controlled method to increase the surface quality and geometricaccuracy. MThe most existing CAM systems used in numerous incremental forming approaches are only applicable for milling machines. In this paper, with the use of self-programmed postprocessors and an Application Programming Interface (API) in a CAM system, movement programs for two cooperating robots can be generated for both forming strategies to produce sheet metal parts with different sizes and complex freeform structures. This CAM-solution for Roboforming is validated bythe forming experiments.


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