asymmetric incremental sheet forming (AISF) has been developed since the early 1990s. (Bruninghaus, 1)

AISF can be used for manufacturing small batch sizes of sheet metal products. (Bruninghaus, 1)

Very flexible process, requiring little to no product specific tooling or parts such as mold and dies. (Bruninghaus, 1)

Therefore free-formed unique parts or small batches can be produced cheaply and speedily. (Bruninghaus, 1)

“Economic studies show a potential usage for batches up to approximately 500 parts (Tuomi and Lamminen, 2004).” (Bruninghaus, 1)

I need to read Tuomi and Lamminen’s paper.

“Since the forming forces needed are not dependent on the dimension of the part AISF can be used to produce even very large parts with inexpensive machines.” (Bruninghaus, 1)

“In the realm of architecture Trautz and Herkrath (2009) examined AISF for manufacturing different elements of a double-layered. facet-like folding structure.” (Bruninghaus, 1)

I need to research Trautz and Herkrath.

“Katajarinne mentioned the production of metal facade elements as a use case for AISF” (Bruninghaus, 1)

Research Katajarinne

“There was also a project on responsive skin where AISF was used to manufacture a mold, which is then used for injection molding UPM Profi – a recycled paper composite – at UCLA Architecture & Urban Design.” (Bruninghaus, 1)

ABB MultiMove allows synchronized movement.

“All types of metal such as steel, aluminum, copper, titan, and even some plastics can be formed” (Bruninghaus, 1)

The maximum sheet thickness for forming “depends on the forces the machine can apply.” (Bruninghaus, 2)

Forming forces are “dependent on material, wall angle, infeed, and tool diameter.” (Bruninghaus, 2)

“Material thinning in formed areas” occurs “since the sheet is fixed.” (Bruninghaus, 2)

The sheet thickness T at every point can be approximately defined for simple forming strategies as: (Bruninghaus, 2)

T = T0 * cos a (Bruninghaus, 2)

where T0 is the initial thickness and a is the corresponding wall angle. This is known as cosine’s law. (Bruninghaus, 2)

“All materials have a certain maximal wall angle that can be formed” (Bruninghaus, 2)

“many steel or aluminum alloys have a maximum wall angle of 60-70 degrees for a single step. Steeper angles can be formed by applying multi-stage strategies” (Bruninghaus, 2)

These multi-stage strategies could be interesting to explore. They allow for steeper angles.

Surface Quality

Dependent on tool diameter and infeed. (Bruninghaus, 2)

“Larger diameters and smaller infeed leads to finer surfaces” (Bruninghaus, 2)

This is interesting, normally smaller tool-heads result in finer surfaces, at least for milling.

“lubricant should be used to minimize friction and enhance results” (Bruninghaus, 2)

Tool marks can be prevented by layering two sheets so the tool only directly interacts with the upper sheet and the lower sheet “is formed indirectly by the deformation of the upper one.” (Bruninghaus, 2)

This additional sheet containing the tool marks is known as the dummy sheet.(Skjoedt and Silva and Bay and Matrins and Lenau, 2007) (Bruninghaus, 2)

Experiment

• Inputs:
• geometry: cone frustum with 60 degree wall angle
• material: DC01
• material thickness: 0.5 mm
• tool material: case hardened X155CrMoV12-1
• tool-head diameter: 12 mm
• path type: helical
• infeed: 0.5 mm

• Results:
• visual appearance of the original direction of rolling disappears
• inner surface has a wavelive structure as a result of the tool movement
• inner surface is glossy
• outer surface is somewhat bumpy with an orange peel effect
• outer surface has matte finish
• Same experiment, but with a dummy sheet causes both sides of the dummy to have a glossy appearance while the other part has a matte finish on both sides.

“for DPIF-P and DPIF-L no direct analogous process in milling exists. thus CAM systems cannot be used.” (Bruninghaus, 3)
So there does not exist CAM systems to calculate tool-paths for Roboforming

Definitions:

AISF: A fixed sheet is deformed step-by-step by a small, mostly spherical, generic tool. It travels along the surface of the final part geometry. This can be done with a layer or with a helical strategy. (Bruninghaus, 1)

SPIF and TPIF can be used with a machine with at least 3 axes. (Bruninghaus, 1)

DPIF-P and DPIF-L: two synchronized machines with at least 3 axes are needed. (Bruninghaus, 1)

Dummy Sheet: the sheet that is directly formed by the tool-head in a layered sheet strategy to minimize tool-marks on the second sheet. (Bruninghaus, 1)