In Incremental Sheet Forming (ISF), the final shape of the piece being manufactured is defined by the hemispheric-tipped tool’s trajectory, which progressively deforms a plane sheet . This is a flexible process that does not require dedicated tools  and can be used in the fabrication of individual parts or small lots of parts .
Compared to conventional sheet formation processes, in ISF the necessary conformation force is reduced due to localized and successive deformations that occur during the process . Nevertheless, it is fundamental to be able to predict the acting forces during the process in order to select the equipment that will be used, such as a CNC milling machine [5, 6], a CNC lathe [7, 8], a robotic arm [9, 10], or a machine designed for this purpose [11, 12].
The process parameters influence the ISF acting forces, and as such, with an increase in tool radius , initial sheet thickness , or step-down , there is also an increase in the force required to achieve the deformation. Materials with greater yield strength [14, 15] also require greater force for the deformation to occur. However, as tool rotation increases , and with it the process temperature , there is a decrease in the required force. The feed rate on the other hand presents little influence over the forces applied to the ISF process .
Duflou et al.  have verified that compared to the tool radius, the sheet’s thickness and the wall angle, the step-down is the least relevant factor among the acting forces in the ISF process.
In the ISF process, the axial force component is the one that presents the greater intensity when compared to radial and tangential components [20, 21]. Depending on the shape of the piece that is being conformed by the ISF, the force versus time graph presents different characteristics . However, in the most common shapes (truncated cone and hyperboloid), it is possible to observe that the axial force component shows a peak during the tool’s axial movement against the sheet, followed by a lower level during the tool’s circular interloping [14, 23].
Li et al.  have developed an analytical model based on the superior limit approach to predict tangential forces in SPIF, applying truncated cone conformation with different wall angles and step-downs. This model showed greater accuracy for step-down values lower than 0.5 mm.
Duflou et al.  and Aerens et al.  have developed regression equations to estimate mean axial force, radial force and tangential force for the truncated cone shape, according to different process parameters and different materials.
Bansal et al.  and Chang et al.  have also developed analytical models to predict ISF force based on stress and contact area between the piece and the tool. Their models presented greater accuracy when compared to the ones proposed by Aerens et al. .
Despite there being several models that allow an estimation of ISF’s mean forces, there is still the need to estimate maximum force, which has a fundamental role in the selection of appropriate equipment to perform the conformation. Therefore, our work aims to evaluate the influence of material properties, sheet thickness and tool diameter in the axial force applied to the conformation tool using the Single Point Incremental Forming (SPIF) process.