Since the computer became an important tool in our life, the design possibilities are greatly increased. However, the translation of this computational design is often done through printed plans, which are then realized with traditional construction methods. All of the information available in digital form, gets lost in this last step. Digital manufacturing is changing this by creating a direct link between design and production. The real object is like an exact copy of the virtual model. SPIF stands for Single Point Incremental Forming. By using an industrial robot to push the metal gradually along a specific tool path, a wide variety of geometries becomes possible. Since there is no mold needed for this process, it is ideal for prototyping and producing small batches. As each panel can be different, free form architecture may also be an interesting field of application. Through one or more test cases I would like to explore the possibilities of this technique in an architectural context. Possible applications are, for example, a self-supporting wall or self-supporting roof construction. For example I modeled a structure, based on an existing project from a carport, and subjected it to a certain load. In the second case a grid of ribs is added on the geometry. We can see clearly that the deflection decreases substantially by using a geometry with more depth. Since it is an integrated process from design to production, it may be interesting to handle all of this in one software. That's why also the tool path, needed to control the robot, is generated in Grasshopper. This plugin provides a parametric environment for Rhinoceros3D. As an output it will give a series of coordinates and direction vectors. Gert-Willem Van Gompel Master of Engineering: Architecture

1. Digital Fabrication
SPIF
Gert-Willem Van Gompel
Master of engineering: architecture
Promotor: Vande Moere Andrew
Corneel Cannaerts (ir. arch.)
Marc Lambaerts (FabLab, dep. Werktuigkunde)
Matthias Mattelaer (DMOA, ir. arch.)
Hans Vanhove (dep. Werktuigkunde)22 October

2. Design Production
Why digital fabrication?

3. Design Production
Why digital fabrication?

4. Missing Link
between design and production
aim of the thesis:
going through this digital proces by means of one or more test cases
digital parametric design and optimalization as well as digital fabrication
How can Single Point Incremental Forming be integrated in a digital design and
production process?
Design Production
Why digital fabrication?

5. What is SPIF?
Figure 17: Single Point Incremental Forming of a cone.
Kim & Park [70] focused their attention o
anisotropy on formability. For this pu
measurements of the major and the m
carried out both along the rolling direct
transverse one (TD). The tests wer
pyramid specimens with a varying too
material was the aluminium alloy 1050-O
σο = 33MPa, R0 = 0.51, R45 = 0.75, R
concluded that formability along the trans
greater when small diameter tools are ut
the rolling direction it is larger with large d
In order to fully understand the increase
AISF, a simple FEM was developed by
and Bambach et al. [69]. They found tha
step size, ∆z, the strain increments impo
decrease and any point is overlapped ot
while strains increase with increasing
from a stress point of view, a negat
distribution is observed under the tool a
elements; in this way, the tool action p
fractures during the process, until the too
with the sheet. Finally, at decreasing ∆z
along the wall decreases too, so that a h
can be imposed without tears occurring.
Nontraditional Forming Limit Diagrams
Forming limit diagrams usually have the
shown as FLC in conventional formin
Εmax, FLDo
3.5
Jeswiet, J., Micari, F., Hirt, G., Bramley, A., Duflou, J., & Allwood, J. (2005). Asymmetric single point incremental forming of sheet metal.
Cirp Annals-Manufacturing Technology, 54(2), 623-649.
oints to generate new, virtual target geometry. This virtual
art geometry forms the basis for the determination of an
mproved toolpath. Using a scale factor of 0.7 was found
provide optimal results for part made of DC04, 1.5 mm.
V shaped
tub
mbrogio et al. [106] use an in-process measurement
stem that allows the determination of deviation between
e anticipated intermediate part geometry and the actually
alized intermediate shape. Per layer (incremental
olpath contour) the observed deviations are measured to
orrect the toolpath geometry for the next contour.
ConeCross Hexagon
he proposed system has been tested with a discrete point
ontact measurement system, used interactively, thus
mulating the availability of real in-process measurement
quipment. The toolpath optimization algorithm has been
sted with pyramid part geometry. The author claims
gnificant accuracy improvements. No quantitative output
however available to evaluate the achievable
mensional accuracy.
HyperbolaDome
5 lobe
shape
EXAMPLES OF APPLICATIONS
he major advantage of asymmetric incremental forming is
can be used to make asymmetric parts, quickly and
conomically, without using expensive dies. Shapes used
demonstrate the abilities of the process are shown in
able 8. Some of the shapes illustrated have been used to
onduct springback experiments, and in determining the
aximum draw angle φ, others are just for demonstration
process abilities.
he asymmetric single and two point incremental forming
ocesses are still in their infancy. Much research work
mains to be done and to do this appropriate shapes are
Table 8: Shapes used to demonstrate the viability of the
process and for experiments.
oven cavity for use in developing country applications. The
last two are for the same manufacturer of custom
motorbikes; the first part is for a motorbike seat and the
second is part of a gas tank.
5.2 Custom manufacture of a solar oven
Truncated pyramid
Faceted
cone
Multi-shaped surface

6. Fig. 5 Top DSIF Method A with a forming tool and a support tool. Bottom DSIF Method B with
two forming tools
40 A. Kalo and M. J. Newsum
Fig. 9 A component with performative textures and features
44 A. Kalo and M. J. Newsum
Kalo, A., & Newsum, M. J. (2014). An Investigation of Robotic Incremental Sheet Metal Forming as a Method for Prototyping Parametric
Architectural Skins. Robotic Fabrication in Architecture, Art and Design 2014, 33-49.
What is SPIF?

7. Kalo, A., & Newsum, M. J. (2014). An Investigation of Robotic Incremental Sheet Metal Forming as a Method for Prototyping Parametric
Architectural Skins. Robotic Fabrication in Architecture, Art and Design 2014, 33-49.
Fig. 10 Comparison of overall geometric improvements with the ‘ribbing’ system
An Investigation of Robotic Incremental Sheet Metal Forming 45
What is SPIF?

8. With the process combination of stretch forming and ISF the forming of global shape and local
features can be performed in an integrated procedure (see Fig. 3).
Figure 3: a) Clamping the sheet blank; b) Generating a preform with stretch forming; c)
Forming details and features with ISF
Compared to pure ISF, the process combination allows for a shorter process time as well as
improved geometrical accuracy and sheet thickness distribution [9]. Compared to pure stretch
forming, the process combination enables the realization of changes in curvature within one panel
geometry and the generation of features, such as the described cones.
Production Routine and Tooling Concept
The tooling concept for the described production approach is a combined die for the stretch
forming and the incremental forming process. Due to the low forming forces in ISF, the use of very
cheap tool material for a die is possible. This way a bonded block of medium density fiberboard
(MDF) has been prepared for the milling of the customized dies. However, the MDF block deforms
under the high pressure induced by the stretch forming, but due to the homogenous structure of
MDF, these deformations are uniform and can easily be taken into account in preliminary
simulation of the process.
The tooling concept is illustrated in Fig. 4 and the steps of the production routine for the
freeform panels are the following:
1) Milling of the die (based on a prepared MDF block)
2) Stretch forming of the first outer layer
3) Trimming of the first outer layer
4) For an optional second outer layer, the steps 2 and 3 will be conducted twice
Figure 6: Produced and joined freeform panel: Smooth outer layer (left); Structural layer (right)
The entire assembled prototype structure is presented in Fig. 7 and serves as proof for th
ducibility as well as the mountability of the panels.
Figure 7: Assembled prototype structure with 8 panels (4 different panel shapes)
Case Study
In order to assess the applicability of the proposed panel system for large-scale applications, a
further case study has been investigated by means of design and structural analysis. The developed
case study is a shell spanning over four foundation points, which build a square of 8.15 m by
8.15 m. The maximum height at the apex is 4.80 m.
Figure 8: Case study design for a large-scale freeform structure
The construction results in 100 panels with a constant effective thickness of 150 mm. To produce
all panels, a die block with a height of only 650 mm is necessary. Due to the double symmetric
Key Engineering Materials Vol. 639 47
Bailly, D., Bambach, M., Hirt, G., Pofahl, T., Della Puppa, G., & Trautz, M. (2015). Flexible manufacturing of double-curved sheet metal
panels for the realization of self-supporting freeform structures. Key Engineering Materials, 639, 41-48.
What is SPIF?

9. Applications?
Project 2XmT by Christopher Romero, Nicholas Bruscia (self-structuring and lightweight architectural screens from sheet metal)
http://blog.archpaper.com/2013/07/reinventing-the-facade-skin-competition-names-four-first-stage-finalists/#.VifKmxDhCAx

10. Eventueel toepassing binnen huidig of toekomstig project van DMOA
Applications?

11. © Otto Wöhr GmbH, Friolzheim
http://brunier-ernst.com/Design-Carport
Applications?

14. description of the tool path can be generated in Grasshopper
Tool path

15. output: list with coordinates and direction vectors
Tool path

16. Set up one or more test cases to show the different design and
production phases.
1. Parametric design
structural optimalization
to minimize stresses and deflections
2. Translate
to translate the 3D model to the robot-instructions
to generate the tool path
3. Digital production
to fabricate the element with an industrial KUKA-robot
4. Assembly
to assemble the individual elements
Andrew Vande Moere
Corneel Cannaerts
Matthias Mattelaer
Hans Vanhove
Marc Lambaerts
Andrew Vande Moere
Corneel Cannaerts
Matthias Mattelaer
Test Cases