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In the recent past, ultrasonic vibration-assisted single-point incremental forming has gained the attention of the metal forming researchers' interest. Being a latest development, the process is not completely established from the point of view of the underlying mechanism and the effect of the process variables on the formability of the component. The amplitude of vibration and frequency of vibration are two ultrasonic process-specific variables which may affect the formability of the component. In this research work, the effect of amplitude of vibration along with forming feed and step-depth have been studied by performing a groove test on AA3003 aluminum sheet. The FFL for the SPIF process is proposed based on the thickness strain of the tensile testing component. The critical value of amplitude of ultrasonic vibration and ultrasonic intensity is identified demarking the ultrasonic softening and ultrasonic hardening zone. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Single point incremental forming has shown immense potential in the manufacture of prototypes. The sheet metal deformation in this technique is carried out by a small hemispherical or flat tool that moves from the sheet periphery to the sheet center while also pushing the sheet down. Simulations of single point incremental forming can be a tedious task since the area required to be formed is large and the two sheet contact area is fairly small. The effect of tool however, affects the entire geometry by causing deflections and radial strains. Hence, it becomes essential to understand the effect of certain parameters that influence the simulation results for this forming process. The paper aims to study factors influencing the simulation of single point incremental forming process. It gives a description of techniques employed to simulate non-linear behavior of sheet metal forming along with the implicit and explicit methodology. Information on the selection of element type including Reduced Enhanced Solid-Shell element is presented. Techniques employed to avoid locking are also discussed.

The aim of this paper is to determine the optimal input parameters for the process in order to ensure the maximum formable wall angle is obtained in a conical frustum with a varying wall angle fabricated using Single Point Incremental Forming (SPIF). The test material was 0.8-mm-thick Ti-6Al-4V titanium alloy sheets, and the test used a tungsten carbide tool with a rounded tip with a radius of 4 mm. Complete workpieces were heated using hot oil with a temperature of about 200 °C, and in addition, the high rotation speed of the forming tool generated an amount of friction heat. The input parameters were tool rotational speed, feed rate, step size, and tool rotation direction. Various oil pressures were used to improve both the accuracy of the components formed and the friction heating process. On the basis of calculations performed by means of the response surface methodology, split-plot I-optimal design responses were obtained by means of polynomial regression models. Models were fitted using REstricted Maximum Likelihood (REML), and p-values are derived using the Kenward–Roger approximation. Observation of the fracture surface of Ti-6Al-4V drawpieces showed that the destruction is as a result of ductile fracture mode. Tool rotational speed and step size are the most significant factors that affect the axial force, followed by feed rate. It was also found that step size is the most significant factor that affects the in-plane SPIF force.

Single point incremental forming has shown immense potential in the manufacture of prototypes. The sheet metal deformation in this technique is carried out by a small hemispherical or flat tool that moves from the sheet periphery to the sheet center while also pushing the sheet down. Simulations of single point incremental forming can be a tedious task since the area required to be formed is large and the two sheet contact area is fairly small. The effect of tool however, affects the entire geometry by causing deflections and radial strains. Hence, it becomes essential to understand the effect of certain parameters that influence the simulation results for this forming process. The paper aims to study factors influencing the simulation of single point incremental forming process. It gives a description of techniques employed to simulate non-linear behavior of sheet metal forming along with the implicit and explicit methodology. Information on the selection of element type including Reduced Enhanced Solid-Shell element is presented. Techniques employed to avoid locking are also discussed. [ABSTRACT FROM AUTHOR]

In this article, the temperatures at sheet-tool interface are observed with non-contact temperature sensors in single point incremental forming at high relative tool velocities. A flat-ended tool was used to form AA5754-H32 sheets, and the results were recorded to study the heat generation from relative tool motion over the sheet metal surface. This paper proposes a new geometry to study the effects of temperature on formability and resulting geometrical errors. The regions of large geometrical errors are presented in cross-sectional and isometric views in colour contrasts. As the tool moves along a prescribed path, a moving comet type temperature structure is observed with two heat generation zones for the first few step downs. The resulting microstructures are observed for each of the following cases and the disparities are reported. Generally, the blankholder is assumed to be at a constant temperature. Results show this is not true; the actual temperature rises with a heat loss to the blankholder via backing plate. High rotation speeds are used, with an upper limit being observed, before forming of sheet metal becomes untenable. At this limit, high wear followed by lubricant fuming is observed. The result at higher rotational speeds is similar to friction stir welding, which are explained in detail by the microstructures. Surface roughness of the formed components as a response to the high tool linear speeds with flat tools is also presented. [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]

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The aim of this paper is to determine the optimal input parameters for the process in order to ensure the maximum formable wall angle is obtained in a conical frustum with a varying wall angle fabricated using Single Point Incremental Forming (SPIF). The test material was 0.8-mm-thick Ti-6Al-4V titanium alloy sheets, and the test used a tungsten carbide tool with a rounded tip with a radius of 4 mm. Complete workpieces were heated using hot oil with a temperature of about 200 °C, and in addition, the high rotation speed of the forming tool generated an amount of friction heat. The input parameters were tool rotational speed, feed rate, step size, and tool rotation direction. Various oil pressures were used to improve both the accuracy of the components formed and the friction heating process. On the basis of calculations performed by means of the response surface methodology, split-plot I-optimal design responses were obtained by means of polynomial regression models. Models were fitted using REstricted Maximum Likelihood (REML), and p-values are derived using the Kenward–Roger approximation. Observation of the fracture surface of Ti-6Al-4V drawpieces showed that the destruction is as a result of ductile fracture mode. Tool rotational speed and step size are the most significant factors that affect the axial force, followed by feed rate. It was also found that step size is the most significant factor that affects the in-plane SPIF force. [ABSTRACT FROM AUTHOR]

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. [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]

Single point incremental forming (SPIF) is an emerging process that is well-known to be suited for fabrication in small series production. The aim of this paper was to determine the optimal input parameters of the process in order to minimise the maximum of both the axial and the in-plane components of the forming force achieved during SPIF and the surface roughness of the internal surface of truncated-cone drawpieces. Grade 2 pure titanium sheets with a thickness of 0.4 mm were used as the test material. The central composite design and response surface method was used to determine the number of experiments required to study the responses through building a second-order quadratic model. Two directions of rotation of the forming tool were also considered. The input parameters were spindle speed, tool feed rate, and step size. The mathematical relations were defined using the response surfaces to predict the surface roughness of the drawpieces and the components of the forming force. It was found that feed rate has an insignificant role in both axial and in-plane forming forces, but step size is a major factor affecting axial and radial forming forces. However, step size directly affects the surface roughness on the inner surfaces of the drawpieces. Overall, the spindle speed −579 rpm (clockwise direction), tool feed 2000 mm/min, and step size 0.5 mm assure a minimisation of both force components and the surface roughness of drawpieces. [ABSTRACT FROM AUTHOR]