Incremental Sheet Forming (ISF) is an umbrella term for a few variations of a sheet metal forming technique. Through ISF, a sheet is formed into the final workpiece through a progression of small, incremental and localized deformations. The sheet is generally formed by a spherically-ended indenter, which can be attached to a CNC machine and moved over a custom-designed, numerically-controlled tool path. Flat-bottomed and parabolic indenter profiles can also be used to achieve different surface finishes and forming limits.
Single-Point Incremental Forming (SPIF) is the most widely-researched method of incremental forming. This technique involves a sheet clamped around the edges, but unsupported underneath and formed by a single indenter.
With Two-Point Incremental Forming (TPIF), on the other hand, a sheet is formed against full or partial dies using one or more indenter tools.
The chief advantage of ISF (particularly SPIF) over conventional sheet forming processes is that no specialized dies are required. This reduces the cost per piece and improves turnaround time for low production runs.
Some experts argue that the formability of the metal materials is better with the localized deformation of ISF than with conventional deep drawing. However, there is some loss of accuracy with the ISF technique.
ISF also offers sustainability, as smaller machines can be used to form the sheet and the material expenses of specialized dies are eliminated. In addition, this production can easily be implemented locally, dispensing with long-distance transportation. Finally, ISF can be used to re-work or re-form old products, a less energy-intensive process than re-melting the material.
Incremental Sheet Forming is an ideal process for small-batch or customized productions with lower tolerance requirements. ISF has particularly appealing applications for the automotive industry and has potential use for medical implants, architectural features, laboratory equipment and specialized parts across many industries.
Current and ongoing research is focused primarily on the potential of the SPIF technique. Although TPIF offers the advantage of improved control and accuracy, the use of specialized parts in many ways negates the benefits of the incremental technique. Research at many universities is focused on improving the capabilities of SPIF in order to benefit further from this method without specialized tooling. Such areas of research currently receiving attention include: developing rolling tools to decrease friction; reducing thinning of sheets after forming; improving the smoothness of the surface; increasing accuracy by eliminating springback; developing new, innovative uses for the ISF process.