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The hybrid method, known as Incremental Sheet Hydro Forming (ISHF), is a combination of the techniques of Incremental Sheet Forming and Sheet Hydro-Forming. The primary concern identified in the incremental sheet forming formation strategy relates to the potential failure of the product due to the thinning of the sheet and subsequent springback. In response to the issue of sheet failure resulting from thinning, a revised iteration of the integrated sheet hydroforming (ISHF) method was proposed. The revised version of the ISHF process has demonstrated notable improvements in the malleability of the material. The ISHF technique entails the movement of a single ball tool along one side of the sheet's surface, while hydraulic support is applied on the opposite side through the use of pressurized hydraulic fluid. The present study sought to investigate the impact of hydraulic support on metal formability and thickness distribution. In addition, a modified variant was also considered. The experimental results are in close agreement with the predictions made by the analytical models. The strain distribution throughout the length of deformation for the sheet has been calculated. The surface quality of the products was found to be satisfactory and a preliminary simulation has been performed. This study examines the influence of process factors, specifically spindle speed (1000/1500/2000 RPM), feed rate (400/600/800 mm/min), tool diameter (8/10/12 mm), and step-down (0.2/0.4/0.6 mm), on the cone-shaped feature at the specimen of aluminum alloy A 5010. The results demonstrated that, through analysis of variance, the most influential factor in the distribution of thickness was speed. Regarding formability, the rate of change was found to be the highest at 50%. [ABSTRACT FROM AUTHOR]

The single point incremental forming process (SPIF) is materialized to form the desired shapes in low-cost sheet metal processing and well suited for low batch components and customized designs. Many modifications have been attempted in recent years to maximize the formability, geometric accuracy and quality of the SPIF formed parts. In this work, an attempt has been made to analyse the influence of process parameters namely ball tool diameter, step size, spindle speed and sheet thickness on final wall thickness, forming force and surface roughness. The optimized results exhibit the desirable formability when the roller ball tool diameter of the tool is 12 mm. The results also project that formability of the sheet metal is minimized when the spindle speed is increased and the ball diameter maximizes the accuracy and surface roughness. Also minimizing the step size increases the product quality features. Upon conducting this multi-response optimization by grey based response surface methodology (RSM) technique It is identified that 12 mm ball diameter of the tool, 0.25 mm step size, 2445 rpm spindle speed, and 2 mm sheet thickness are the obtained optimized SPIF process parameters as confirmed through confirmation experiments. [ABSTRACT FROM AUTHOR]

AA-6061 aluminum alloy is extensively used in automobile and aerospace industries due to its high strengthto- weight ratio. However, this material shows limited formability in age-hardened condition at room temperature. Therefore, a new forming method known as single point incremental forming (SPIF) to deform the sheet was adopted. The SPIF experiments and finite element method (FEM) simulation were performed to form the sheet into the desired conical shape. Digital image correlation (DIC) method was used to measure the major and minor strains post deformation experimentally, and results were compared with FEM results. Detailed microstructural study was performed to understand the deformation behavior of AA-6061 aluminum alloy sheets during SPIF. It is observed that plastic anisotropy has strong effect on microstructure and texture development in different directions of AA-6061 alloy sheet during SPIF. It is also observed that volume fraction of goss and S texture components remains stable, whereas volume fraction of cube and brass texture changes significantly. [ABSTRACT FROM AUTHOR]

In this research, a new hybrid forming strategy is proposed and investigated numerically and experimentally to improve the formability in single point incremental forming (SPIF). At the first stage, the hydraulic bulging of the sheet metal is performed under a specified fluid pressure to obtain an intermediate shape, then the fluid pressure is removed and the bulged sheet is inverted upside down. Finally, the SPIF of the truncated cone with a certain wall angle is carried out on the pre-bulged sheet. To this end, a die set was designed and manufactured. To study the deformation mechanics and the thickness distribution, finite element modeling using Abaqus/Explicit was employed. The maximum achievable forming depth and the thinning in the hybrid forming strategy were compared with those in the single-stage and the equivalent two-stage SPIF. Results of the 70° wall angle cone show that by implementing the two-stage hybrid forming, the forming depth and the thinning can be improved by 26 and 45% compared to the single-stage SPIF, respectively. On the other hand, the equivalent two-stage SPIF can lead to an improvement of about 10% in the forming depth compared to the single-stage SPIF. [ABSTRACT FROM AUTHOR]

Single point incremental forming (SPIF) is highly flexible sheet metal forming process used for small quantity production and new product development. The product with high strength, good surface finish, and higher formability has paramount importance in industrial and marine applications. SPIF has been carried out on AA5052-H32 aluminum alloy which has high strength and difficulty in the conventional forming process. The response characteristics such as surface roughness $$({R}_{\mathrm{a}})$$ and maximum forming angle $$(\varnothing _{\mathrm{max}})$$ were evaluated by considering the independent process parameters such as spindle speed, table feed rate, step depth, tool diameter and sheet thickness through the design of experiments. The step depth and sheet thickness are the most influencing parameters for average surface roughness and maximum forming angle, respectively. It is found that neither the surface roughness nor the forming angle of formed sheets feels the effects of spindle speed significantly. An empirical relation has been formulated, and experiments were carried out to verify the reliability of the developed regression model. [ABSTRACT FROM AUTHOR]

Single point incremental forming (SPIF) has higher formability limits than other sheet metal forming processes including stamping, and is therefore a desirable method of forming sheet metal components. To take advantage of this high formability it is necessary to understand how to maximise the limits through manipulation of parameters, increasing the likelihood of component success. In this paper, a systematic quantitative literature review was undertaken analysing experiments and results from 35 papers that studied the effect of process parameters on formability in SPIF. Collective results are presented regarding material thickness, tool diameter, tool shape and type, step down, feed rate, spindle speed and rotation direction, and some parameter interactions. The analysis provides evidence to support the hypothesis of an ideal operating range for each parameter and interdependency of parameters. A lack of focus in the literature on parameter interactions was found. A framework for important experimental parameters is proposed based on the review. Statement of originality Quantitative analysis of research presented in the literature about parameter effects on formability in SPIF. [ABSTRACT FROM AUTHOR]

The aim of this paper is twofold: firstly, to identify a new failure mechanism by in-plane shear cracking in single point incremental forming (SPIF) and, secondly, to present a simple geometry to be produced by SPIF that is capable of providing fracture strain pairs to define the in-plane shear fracture forming line (SFFL) corresponding to crack opening by mode II of fracture mechanics. The methodology draws from the analysis of several pioneering studies in SPIF, where strain loading paths evolve in the tension–compression quadrant of the principal strain space, to setting up an experimental work plan aimed at identifying the forming conditions where crack opening by thinning under tension is replaced with crack opening by in-plane shear (distortion with limited thinning). The overall procedure makes use of circle-grid analysis and thickness measurements before and after fracture at several locations along the cracks in order to obtain the ‘gauge length’ strains. It is shown that a truncated four-lobe conical shape with varying drawing angle can be successfully employed to define the SFFL and to reopen the discussion around the physics behind plastic flow and fracture in SPIF. [ABSTRACT FROM AUTHOR]

Highlights: [•] New experimental methodology to determine the fracture loci in sheet metal forming. [•] Revisiting the fracture forming limit line in the light of thickness reduction and stress triaxiality. [•] Characterization of the in-plane shear fracture forming limit line on the basis of critical distortion and plastic shear work per unit of area. [Copyright &y& Elsevier]

The article presents results of analysis of applications of incremental forming technology for production of composite moulds. Results of the research of formability of sheet metal based on single point incremental forming are presented. This technology is particularly useful for manufacturing new prototypes and moulds for composite structure manufacturing. The publication introduces new technological equipment for incremental sheet metal forming. The research was performed using sheet blanks of aluminium alloys AW5754 and AW1050. The article analyses the influence of geometrical parameters of parts (moulds for composites forming) on formability of sheet metal and influence on the product properties. [ABSTRACT FROM AUTHOR]

The aim of this paper is to provide an overview into the development and application of single point incremental forming in rapid prototyping and rapid manufacturing of polymer sheet products that will enable the readers to recognize the key influential variables, to identify the process feasibility window, to diagnose possible sources of failure and to understand the routes for selecting the most appropriate materials and operative conditions. The methodology draws from independent determination of mechanical properties and formability limits of polymers to rapid prototyping of truncated conical and pyramidal parts. The investigation is supported by circle grid analysis. Results and observations are explained in the light of theoretical framework based on membrane analysis that is capable of modelling the cold plastic deformation of polymers with pressure-sensitive yield surfaces. The results show that the single point incremental forming of polymer sheets, performed on conventional CNC machining centres, is a cost-effective innovative technology for product development in a manufacturing environment. Applications may span from products with very high depths, taking advantage of the excellent formability of polyethylene terephthalate, to applications in polycarbonate where transparency is kept during cold forming. [ABSTRACT FROM AUTHOR]

Abstract: A recently developed AlMgSc alloy is studied since this material, which is well adapted to the aeronautic domain, is poorly known. The first objective is to reach a better knowledge of this alloy to provide the missing useful information to the aeronautic industry and to help research institutes who want to simulate sheet forming processes by Finite Element (FE) simulations. A set of experimental tests has been performed on the as-received sheets, material laws have been chosen and the corresponding material parameters have been adjusted to correctly describe the material behaviour. The second objective is to study the applicability of the Single Point Incremental Forming process (SPIF) on this material. Truncated cones with different geometries were formed and the maximum forming angle was determined. A numerical model was developed and proved to be able to predict both the force evolution during the process and the final geometrical shape. Moreover, the model helps reaching a better understanding of the process. The characterisation method described in this research and applied on the AlMgSc alloy can be extended to other alloys. In addition, the numerical simplified model, able to accurately describe the SPIF process with a reduced computation time, can be used to study more complex geometries. [Copyright &y& Elsevier]

Abstract: This paper is focused on the single point incremental forming (SPIF) of tailored welded blanks produced by friction stir welding (FSW). Special emphasis is placed on the know-how for producing the tailored blanks and on the utilization of innovative forming strategies to protect the welding joint from the rotating single point-forming tool. Formability of the tailor welded blanks (TWB) is evaluated by means of benchmark tests carried out on truncated conical and pyramidal shapes and results are compared with similar tests performed on conventional reference blanks of the same material. Results show that the combination of SPIF with tailored welded blanks produced by FSW seems promising in the manufacture of complex sheet metal parts with high depths. [Copyright &y& Elsevier]

Abstract: Polymers represent an important percentage of the raw materials currently utilized in manufacturing applications but their conventional processing techniques are mainly suitable for mass production. Growing requirements of low volume, high quality, customized products are triggering the need for developing innovative flexible polymer processing techniques that are capable of dealing with the new agile manufacturing trends involving very short life cycles and very short development and production lead times. This paper is concerned with these issues and is focused on the possibility of employing the single point incremental forming technology currently being developed for flexible sheet metal forming applications, for producing low cost, small-batch, high-quality polymeric sheet components. Experimentation is based on the utilization of an ordinary CNC milling machine and a single point forming tool to shape commercial PVC sheets and the overall investigation is centred on the characterization and evaluation of the formability limits of the process as a function of the major operating parameters. Results show that single point incremental forming of commercial PVC sheets at room temperature seems promising for the manufacture of complex polymer sheet components with very high depths. [Copyright &y& Elsevier]

In recent work, the present authors constructed a closed form analytical model that is capable of dealing with the fundamentals of single point incremental forming (SPIF) and explaining the experimental and numerical results published in the literature over the past couple of years. The model is based on membrane analysis with in plane contact frictional forces but is limited to plane strain, rotationally symmetric conditions. The aim of the present paper is twofold: first, to extend the previous closed form analytical model into a theoretical framework that can easily be applied to the different modes of deformation that are commonly found in general single point incremental forming processes and, second, to investigate the formability limits of SPIF in terms of ductile damage mechanics and the question of whether necking does, or does not, precede fracture. Experimentation by the present authors, together with data retrieved from the literature, confirms that the proposed theoretical framework is capable of successfully addressing the influence of the major parameters of the SPIF process. It is demonstrated that neck formation is suppressed in SPIF, so that traditional forming limit diagrams are inapplicable to describe failure. Instead fracture forming limit diagrams should be employed. [ABSTRACT FROM AUTHOR]

Lightweight materials, such as titanium alloys, magnesium alloys, and aluminium alloys, are characterised by unusual combinations of high strength, corrosion resistance, and low weight. However, some of the grades of these alloys exhibit poor formability at room temperature, which limits their application in sheet metal-forming processes. Lightweight materials are used extensively in the automobile and aerospace industries, leading to increasing demands for advanced forming technologies. This article presents a brief overview of state-of-the-art methods of incremental sheet forming (ISF) for lightweight materials with a special emphasis on the research published in 2015–2021. First, a review of the incremental forming method is provided. Next, the effect of the process conditions (i.e., forming tool, forming path, forming parameters) on the surface finish of drawpieces, geometric accuracy, and process formability of the sheet metals in conventional ISF and thermally-assisted ISF variants are considered. Special attention is given to a review of the effects of contact conditions between the tool and sheet metal on material deformation. The previous publications related to emerging incremental forming technologies, i.e., laser-assisted ISF, water jet ISF, electrically-assisted ISF and ultrasonic-assisted ISF, are also reviewed. The paper seeks to guide and inspire researchers by identifying the current development trends of the valuable contributions made in the field of SPIF of lightweight metallic materials. [ABSTRACT FROM AUTHOR]