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Incremental sheet forming (ISF) is a relatively new flexible forming process. ISF has excellent adaptability to conventional milling machines and requires minimum use of complex tooling, dies and forming press, which makes the process cost-effective and easy to automate for various applications. In the past two decades, extensive research on ISF has resulted in significant advances being made in fundamental understanding and development of new processing and tooling solutions. However, ISF has yet to be fully implemented to mainstream high-value manufacturing industries due to a number of technical challenges, all of which are directly related to ISF process parameters. This paper aims to provide a detailed review of the current state-of-the-art of ISF processes in terms of its technological capabilities and specific limitations with discussions on the ISF process parameters and their effects on ISF processes. Particular attention is given to the ISF process parameters on the formability, deformation and failure mechanics, springback and accuracy and surface roughness. This leads to a number of recommendations that are considered essential for future research effort.

Incremental sheet forming of titanium and its alloys has a significant role in modern manufacturing techniques because it allows for the production of high-quality products with complex shapes at low production costs. Stamping processes are a major contributor to plastic working techniques in industries such as automotive, aerospace and medicine. This article reviews the development of the single-point incremental forming (SPIF) technique in titanium and its alloys. Problems of a tribological and microstructural nature that make it difficult to obtain components with the desired geometric and shape accuracy are discussed. Great emphasis is placed on current trends in SPIF of difficult-to-form α-, α + β- and β-type titanium alloys. Potential uses of SPIF for forming products in various industries are also indicated, with a particular focus on medical applications. The conclusions of the review provide a structured guideline for scientists and practitioners working on incremental forming of titanium and titanium alloy sheets. One of the ways to increase the formability and minimize the springback of titanium alloys is to treat them at elevated temperatures. The main approaches developed for introducing temperature into a workpiece are friction heating, electrical heating and laser heating. The selection of an appropriate lubricant is a key aspect of the forming process of titanium and its alloys, which exhibit unfavorable tribological properties such as high adhesion and a tendency to adhesive wear. A review of the literature showed that there are insufficient investigations into the synergistic effect of rotational speed and tool rotation direction on the surface roughness of workpieces.

This paper explores the development and application of the incremental forming process, an innovative method for manufacturing complex parts with high flexibility and low tooling costs. The review categorizes three key process variants: Single Point Incremental Forming (SPIF), Two Point Incremental Forming (TPIF), and Incremental Forming with Conjugated Active Plate (IFCAP). This study demonstrates the significant effects of these process variants on part accuracy and material behavior, particularly under varying process conditions. This study identifies critical technological parameters such as tool diameter, feed rate, and vertical step size. The findings also demonstrate the role of optimized toolpaths and lubrication in improving process efficiency. Applications of incremental forming across various industries, including automotive, aerospace, medical, and construction, demonstrate its versatility in prototype production and small-series manufacturing. These results contribute to a deeper understanding of incremental forming, offering practical recommendations to enhance precision, scalability, and material formability, and supporting future innovations and broader industrial applications.

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.

The employment of a green manufacturing process can directly save energy and materials in industrial sectors. Single Point Incremental Forming (SPIF) is an agile and flexible method of fabricating sheet material components and exempts the use of dedicated die-sets which further makes it a choice of green manufacturing. Furthermore, the customized components can be easily fabricated by SPIF economically. The surface quality of fabricated parts can greatly decide the suitability and sustainability of the process in various applications. This work investigates the impact of significant process factors on the roughness of the parts during the SPIF process. The average roughness has been considered to determine the surface quality. The increment in the value of wall angle and step size resulted in the increment in Ra value of formed components drastically. It was also observed that as the forming angle was raised from a lower level (60°) to a higher level (68°), the Ra value was found to increase significantly.

A significant augmentation in the obsolescence of traditional forming techniques results in the strong requirement of developing an emerging and flexible process to fabricate the user-ready parts in the manufacturing units. Single Point Incremental Forming (SPIF) also known as “negative incremental forming” has shown its viability as a novel and emerging forming method for fabricating the customized and batch-type products of sheet materials to satisfy the need of various potential sectors including medical, automobile, and aerospace. This method directly exempts the involvement of dedicated die-sets and turns into the choice of green manufacturing. The surface quality of fabricated parts can greatly decide the suitability and sustainability of the process in various applications. In the current study, the impact of wall angle and tool rotation have been explored for surface roughness during SPIF. Results revealed that the increase in spindle speed resulted in the decrease of Ra value of formed components. Moreover, the Ra value of formed components was found to decrease by 50 % when the experimental condition was changed from the combination of higher levels of wall angle and “free-to-rotate” condition of spindle speed to the combination of lower levels of wall angle (60°) and a higher level of spindle speed (1500 rpm).

The article presents the results of the analysis of the influence of incremental sheet forming process parameters on surface roughness measured on both sides of conical drawpieces made from pure titanium Grade 2 sheets. The experimental plan was created on the basis of a central composite design. The study assumed the variability of feed rate, spindle speed, and incremental step size in the following range: 500–2000 mm/min, 0–600 rpm, and 0.1–0.5 mm, respectively. Two strategies differing in the direction of the tool rotation in relation to the feed direction were also analysed. Analysis of variance is performed to understand the adequacy of the proposed model and the influence of the input parameters on the specific roughness parameter. The sensitivity of the process parameter on the selected surface roughness parameters was assessed using artificial neural networks. It was found that the change in the surface roughness of the inner surface of the drawpiece is not related to the change of surface roughness of the outer side. The morphology of the outer surface of the draw pieces was uniform with a much greater profile height than the inner surface that had interacted with the tool. Taking into account the outer surface of the drawpiece, the direction of tool rotation is also most closely correlated with the parameters Sa, Sz, and Sku. Step size and feed rate provide the highest information capacity in relation to skewness and kurtosis of the inner surface of the drawpiece.

Fracture prediction using ductile damage models in incremental sheet metal forming has recently become an indispensable approach. Prediction accuracy of damage models depends upon the approach followed to model the anisotropic nature of the sheet metal to a large extent. In this regard, this study is performed to understand the degree of influence of anisotropy in fracture prediction compared to the isotropic model. The Bao and Wierzbicki (2004) damage model was used for predicting fracture in the case of single-point incremental forming (SPIF) of the AA6061-T6 sheet. von Mises and Hill48 yield functions were used to develop the isotropic and anisotropic material behavior in finite element (FE) simulations. A “D” shape geometry with a wall angle of 70° was formed till the fracture. The damage model was calibrated with fracture strains obtained using digital image correlation (DIC) in uniaxial and shear tests. The accuracy of the developed finite element model was validated by comparing the forming height, thickness, and surface strains with experiments. A non-linear damage accumulation rule was utilized to capture the non-linear loading scenarios, and it was calibrated using SPIF of a cylindrical geometry. Finite element simulation using the Hill48 yield function predicted forming height more accurately when compared to the isotropic von Mises yield function.

When using a unique tool with different controlled path strategies in the absence of a punch and die, the local plastic deformation of a sheet is called Single Point Incremental Forming (SPIF). The lack of available knowledge regarding SPIF parameters and their effects on components has made the industry reluctant to embrace this technology. To make SPIF a significant industrial application and to convince the industry to use this technology, it is important to study mechanical properties and effective parameters prior to and after the forming process. Moreover, in order to produce a SPIF component with sufficient quality without defects, optimal process parameters should be selected. In this context, this paper offers insight into the effects of the forming tool diameter, coolant type, tool speed, and feed rates on the hardness of AA1100 aluminium alloy sheet material. Based on the research parameters, different regression equations were generated to calculate hardness. As opposed to the experimental approach, regression equations enable researchers to estimate hardness values relatively quickly and in a practicable way. The Relative Importance (RI) of SPIF parameters for expected hardness, determined with the partitioning weight method of an Artificial Neural Network (ANN), is also presented in the study. The analysis of the test results showed that hardness noticeably increased when tool speed increased. An increase in feed rate also led to an increase in hardness. In addition, the effects of various greases and coolant oil were studied using the same feed rates; when coolant oil was used, hardness increased, and when grease was applied, hardness decreased.

Single point incremental forming (SPIF) is becoming more and more widely used in the metal industry due to its high production flexibility and the possibility of obtaining larger material deformations than during conventional sheet metal forming processes. This paper presents the results of the numerical modeling of friction stir rotation-assisted SPIF of commercially pure 0.4 mm-thick titanium sheets. The aim of this research was to build a reliable finite element-based thermo-mechanical model of the warm forming process of titanium sheets. Finite element-based simulations were conducted in Abaqus/Explicit software (version 2019). The formability of sheet metal when forming conical cones with a slope angle of 45° was analyzed. The numerical model assumes complex thermal interactions between the forming tool, the sheet metal and the surroundings. The heat generation capability was used to heat generation caused by frictional sliding. Mesh sensitivity analysis showed that a 1 mm mesh provides the best agreement with the experimental results of total forming force (prediction error 3%). It was observed that the higher the size of finite elements (2 mm and 4 mm), the greater the fluctuation of the total forming force. The maximum temperature recorded in the contact zone using the FLIR T400 infrared camera was 157 °C, while the FE-based model predicted this value with an error of 1.3%. The thinning detected by measuring the drawpiece with the ARGUS non-contact strain measuring system and predicted by the FEM model showed a uniform thickness in the drawpiece wall zone. The FE-based model overestimated the minimum and maximum wall thicknesses by 3.7 and 5.9%, respectively.