**3. Formative processes and TRIZ principles for new rapid physical 3D modelling techniques**

Frequently, the designer uses two-dimensional sketching and computer-aided for conceptual design (Buchal 2002) or physical modelling using the materials mentioned in section 1 (Schrage 1993). Hand-based techniques are used because their flexibility, adaptability, creativity generation, and cost (Jenkins and Martin 1993).

Traditional rapid prototyping techniques belong to additive manufacturing processes. Manufacturing processes are mainly based on subtractive manufacturing processes (Suh et al. 2010). In this chapter we exploit the less known and used family of formative manufacturing processes (Buswell 2007) to build a new rapid 3D physical modelling technique. Formative processes have been used mostly in art. There are many examples of this type of processes in sculpture3. They have been also used in jewels since thousands of years back. Formative manufacturing processes have the following advantages: they are environmental friendly and economic since the material can also be composed by wasted material. On the contrary, subtractive and additive manufacturing processes generate wasted material and in particular additive manufacturing processes are very expensive. Formative manufacturing processes use only the necessary material without almost any waste. The Origami technique (Demaine and O'Rourke 2007) is an example of formative manufacturing processes. Many wire bending based products are fabricated in mass. Some examples are jail birds, wire baskets, cookware tools, mice tramps, and hooks among many others.

The new rapid physical modelling technique we propose in this chapter is called Rapid Physical 3D Wireframing. The name comes from the final 3D object we want to achieve. A wire-frame model is a visual presentation of a three dimensional or physical object used in 3D computer graphics. In our case we intend to reproduce a physical 3D wireframe object. We do not want to call rapid physical 3D sketching, rapid 3D prototyping, and neither rapid physical mock-up. The reason is that the final product of this process is not a sketch, not a mock-up, and neither a prototype. There are a plenty of patents and commercial machines that blend wires but their use is not for the conceptual design phase.

TRIZ is a problem-solving approach developed from the patent mining experience of the Russian Genrich Altshuller and his colleagues. TRIZ in English means Theory of Inventive Problem Solving (TIPS) (Orloff 2010). Altshuller discovered that at least 80% of the patents were based on some general principles. Training people on such general principles gives them the possibility to invent solutions to problems in a structured form. The main TRIZ concept is contradiction. Technical contradictions emerge when two associated necessities from a product or problem are in conflict. The key issue in TRIZ methodology is to find the

176 Industrial Design – New Frontiers

Table 1 is presented to provide a systemic view of the engineering design thinking. Additionally, we add the INNOWIZ1 design framework. The INNOWIZ framework synthesizes the design thinking (Plattner et al. 2010). INNOWIZ creators state that any stage of the general design process can be divided in the four stages (like a fractal). At the table, we also added the general TRIZ methodology (Orloff 2010). The fact that people has embedded the engineering design process in their thinking has been recognized as

Now based on stages 1 and 2 from Table 1, we present in Figure 1 the innovation funnel (Buxton 2007) for our integrated course (Cárdenas 2009). The innovation funnel shows that several techniques are used to decide the final concept (or solution). The innovation funnel is composed by several divergent and convergent phases. The reader can notice that Rapid Prototyping might also be used not only after the concept is finally selected to demonstrate or prove aspects of the design but also at different moments during the innovation funnel. In such sense Rapid Prototyping can be used to help defining the concept of the system (e.g.

engineering design thinking (Dym et al. 2006).

Fig. 1. Innovation funnel for our integrated course (Cárdenas 2011).

Rapid Prototyping has been traditionally used after the concept is defined and as a way to validate the concept. Several techniques for rapid prototyping have been developed (Chua et al. 2010), and most of them are based on the layered principle. Because of that, the term additive manufacturing has been recently adopted to describe rapid prototyping techniques (Gibson et al. 2009). The application of Rapid Prototyping in early stages of the design process has been previously proposed (Simondetti 1998). The time extent for applying Rapid Prototyping in the innovation funnel as indicated in Figure 1 is known as the conceptual

in terms of size and form).

design phase (Bruno et al. 2003).

1 http://www.innowiz.be/

<sup>2</sup> http://www.arduino.cc

<sup>3</sup> http://www.wirelady.com/

TRIZ-Based Design of Rapid 3D Modelling Techniques with Formative Manufacturing Processes 179

respectively were between 15 to 20 years old; 14% and 42% respectively were between 21 and 25 years old; 19% of the advanced students were more than 25 years old. 70% and 58% of

Work done by hand can achieve a high level of quality. There are a lot of examples from the art craft domain. Automate such manufacturing processes is a highly complex task since it demands mechatronics systems with many degrees of freedom. To propose a design process for wirebending we must evaluate first the work done by hand. The first experiment was entitled "freeform construction of 3D objects by means of wire bending". First, the students were asked to register general information. Then, a brief introduction to the rendering process was given; the main focus was to provide a background about the wire-frame version of objects. Wireframing is used as an intermediate step to obtain rendering. Wireframing is an implemented function of several CAD/CAE platforms. Wireframing form depends on the finite element chosen (e.g. circle, square, triangle, etc.). Wireframing can be also seen as a kind of mesh. Third, students were asked to make three sketches where they will present the mesh of a cup (divergent phase). The cup was chosen because it is a well known form and a common object found everywhere. They were asked to sketch the cups with three different meshes. For the convergent phase, students were asked to choose the mesh based on some criteria: originality, design, easy to build, etc. Fourth, students were provided by enough material of 16 AWG wires (same size that will be used in the expected machine). They were asked to build their prototype by hand. Figure 2 shows two pictures of this experiment. Finally a questionnaire was applied to the participant students. In the

novice and advanced students respectively do not have industrial experience.

following section we will present the more important results of this experiment.

Once the formative process was known by the students and they provided their qualitative evaluation to such process. In the second experiment we proposed a methodology that students followed also by hand. The objective of this experiment was to compare qualitatively the freeform style previously experimented with our methodology to manufacture the 3D object by wire bending. Therefore, the second experiment was entitled "MDSU-based construction of 3D objects by means of wire bending". The MDSU is our proposed methodology. It stands for Mesh, Unfolding (*Desdoblado*), Separation and Union

Fig. 2. Pictures from the first experiment.

**5.2 Second experiment** 

**5.1 First experiment** 

main contradictions in the technological innovation. According to Altshuller, there are three categories of contradictions: technical, physical and human. The methodology proposed by Altshuller consists on a series of the following sequential steps: finding a problem, abstractize the original problem to find the general contradiction, use the general principles to solve the general problem, concretize the general solution to the original problem. In Table 1 we have included this general procedure as a general engineering design thinking methodology. The use of this methodology will be explained in the following section.
