Production Processes - Single point incremental forming (SPIF)

Single Point Incremental Forming (SPIF) is a recently developed dieless sheet metal part production technique that is gradually evolving towards industrial applicability. In this process a sheet metal part is formed in a stepwise fashion by a CNC controlled rotating spherical tool without the need for a supporting (partial) die. This technique allows a relatively fast and cheap production of small series of sheet metal parts.

NC milling machine configuration used for forming a conical "cup" part

In the SPIF process generic, freeform shapes can be produced using a standard, spherical, CNC controlled tool. The process starts from a flat sheet metal blank, clamped on a sufficiently stiff rig and mounted on the table of a CNC machine. To form a part, the machine tool follows a pre-programmed contour, similar to a conventional milling operation. The main advantage of this method is that no die is required, making this an ideal process for rapid prototyping or small batch production.

Today, the SPIF process is still premature and needs further development before it can be used for industrial applications. The part accuracy and thickness variations, and therefore the resulting part strength, are some of the key concerns. As recent market analysis studies have shown, accuracy is one of the most important limiting factors for the deployment of SPIF in industrial applications.

Our research aims at a more fundamental study of the SPIF process including:

• Material characterization
• Forming Limit Diagrams
• Development of suitable tool path strategies
• Development of optimal machine configurations

A CAD model with a toolpath generated for the SPIF process

Reporting

Different case studies have been performed by our research group. A short summary of the results regarding accuracy, wallthickness and required forces can be found below:

• Manufacturing of a solar cooker using SPIF
• Manufacturing of a cranial plate using SPIF (medical application)
• Force measurements

Experimental Equipment

We have two dedicated incremental forming setups at our disposal :

• ACIERA F45 CNC 4-axis milling machine : Workarea 230mm x 230mm
• KUKA KR210 2000 Robot setup : Workarea 1m x 1m

Publications

Publications regarding spif

Contact information

Prof.Dr.ir. Joost Duflou