**3. Classifying physical models**

Physical models in product development in general, and industrial design in specific, may be classified in several ways. It is best to understand these classifications in order to understand the impact of digitalization and rapid model making has on industrial design.

Broek et al. [3] classify and exactly describe physical models according to usage and type as:



**Table 1.** *Classification of physical models [4].*


Of the classification by Broek et al. [3], classic industrial design is interested in *visualisation, functionality-testing, marketing,* and *proof-of-concept* models. Isa and Liem [4] state that there are, '… very limited classifications which clearly explained the actual characteristics and functions of each physical models in the design process' and that the lack of classifications makes it, '… harder for the designer to understand the true potential of physical models in various fields'. Isa and Liem [4] give a first level classification as shown in **Table 1**.

Isa and Liem [4] have also elaborated on the classification from Broek [3] which is shown in **Table 2**. 3 What **Tables 1** and **2** show are where the practice of physical model making in the design process has arrived at in the first part of the 21st century. This has been made possible through several key factors along the way. It

**133**

**Table 2.**

*Classification of physical models according to usage [4].*

*Rapid Physical Models: A New Phase in Industrial Design*

is important to understand what has changed from 100 years ago as summarised in **Table 3** showing the progress based on the materials and the method of fabrication/manufacture of the physical models. It can be seen from **Table 3** that, as the method of fabrication of physical models progressed from hand fabricated models to automated model making, the accuracy of the dimensions and the ability to

*DOI: http://dx.doi.org/10.5772/intechopen.88788*

<sup>3</sup> Isa and Liem [4] have included Technology and have excluded Editing in the classification shown in **Table 2**. The references cited in **Table 2** refers to the source article [4].

#### *Rapid Physical Models: A New Phase in Industrial Design DOI: http://dx.doi.org/10.5772/intechopen.88788*

*Design and Manufacturing*

models.

*Classification of physical models [4].*

**Table 1.**

process.

is shown in **Table 2**.

be change manually [3].

4.*Marketing*: a marketing model or presentation model will express the added design value of the product to outsiders of the design process. The finishing quality and being a look-alike of the final product are crucial for this type of

5.*Proof-of-concept*: a very detailed model made in the final stage of design to

6.*Editing*: editable models are assembled or composed models and, when needed, decomposed again and rebuild with different (shape) components to create an

7.*Communication*: a communication model is applicable for communication with the inside of the design process or for explanation to the related authorities to provide them with a better understanding what is going on in the design

8.*Process*: a process model is a kind of proto-model or protoshape like a CAD design or a physical model, which is treated in a reverse engineering way. In those models the progress of a design is captured, and the shape of a model can

Of the classification by Broek et al. [3], classic industrial design is interested in *visualisation, functionality-testing, marketing,* and *proof-of-concept* models. Isa and Liem [4] state that there are, '… very limited classifications which clearly explained the actual characteristics and functions of each physical models in the design process' and that the lack of classifications makes it, '… harder for the designer to understand the true potential of physical models in various fields'. Isa and Liem [4]

Isa and Liem [4] have also elaborated on the classification from Broek [3] which

<sup>3</sup> Isa and Liem [4] have included Technology and have excluded Editing in the classification shown in

cal model making in the design process has arrived at in the first part of the 21st century. This has been made possible through several key factors along the way. It

What **Tables 1** and **2** show are where the practice of physi-

qualify the product design against the requirements.

adapted version of the same model.

give a first level classification as shown in **Table 1**.

**Table 2**. The references cited in **Table 2** refers to the source article [4].

3

**132**


**Table 2.**

*Classification of physical models according to usage [4].*

is important to understand what has changed from 100 years ago as summarised in **Table 3** showing the progress based on the materials and the method of fabrication/manufacture of the physical models. It can be seen from **Table 3** that, as the method of fabrication of physical models progressed from hand fabricated models to automated model making, the accuracy of the dimensions and the ability to

**Table 3.**

*Progress of physical model making for industrial design.*

realise models of complex/sophisticated form is increased. This shift from simple methods to complex process in model making has been accompanied by technological advancement, mainly in computer aided design (CAD) and computer numerical control (CNC) which are the keys to today's model making techniques such as high speed CNC, laser cutting and 3D printing. The availability of accurate 3D data produced by CAD software enables reliable CNC. According to Mike Lynch,4 Founder and President of CNC Concepts Inc., CNC offers three distinct benefits, the first being the **reduced skill level** due to improved automation. The second benefit is the **consistency and accuracy** of the parts that are produced and third benefit is the **flexibility** to change to many different parts or models.

During the starting period of model making during the last century, the emphasis laid on the skill of the model maker. Those who took up this profession were craftsmen or, many a times, the designers. The dimensional accuracy of the model.

as well as the shape, form and finishes depended on the skill level of the model maker. With the advent of 'rapid' methods this skill was embedded in the machine and method itself and the model maker has more of a technician's role in the model making process. How did this change happen? This is best explained in the next section on computer aided design (CAD).

#### **3.1 Enter CAD**

The most significant progress in product design and development occurred with the advent of computer aided design (CAD) in the 1960s. CAD as an idea and working prototype was derived from the idea of CNC (which was developed by Dr. Patrick J. Hanratty in 1957) and first developed by Ivan Sutherland at MIT as SKETCHPAD which showed the capabilities of computers with display in technical drawing. The full potential of CAD as a three-dimensional development tool was realised through

**135**

*Rapid Physical Models: A New Phase in Industrial Design*

software such as Pro/Engineer, UniGraphics, CATIA in the 1980s. With CAD, industrial designers were able to design in 3D and define the details on the surface and the various features within the 3D environment, which then becomes 3D data that is utilised by any CNC controlled system to machine or manufacture the design with a high level of fidelity in terms of dimensions and details. Today industrial designers use very sophisticated software such as Autodesk 360 and Rhinoceros, which allows for not only 3D data transfer for model making, but also for 'photo-realistic' renderings and to transfer the model to engineers for detail development. **Figure 12** shows the high level of flexibility that CAD offers including visualisation in sketch form

Having 3D data that is transferrable with high reliability of the design concepts is the first step towards the realisation of rapid physical models. Many formats for transferring reliable 3D data have been developed, the most common ones being IGES, STEP, STL and OBJ. In the field of rapid model making, IGES and STEP are predominantly used in high speed CNC while STL and OBJ formats are the most

more for 2D graphics and object rather than for 3D format. STEP is perhaps the first true 3D file convertor which relates to ISO 10303 and is widely used to transfer 3D data created by different CAD software platforms as well as transfer data to CNC programmers. STL is pure 3D information on geometry and shapes and does not hold any information colour, textures, etc. OBJ file format stores both form (geometry and shape) data as well as colour and texture information and is very useful in

Three distinct advances in machining technology has paved the way for rapid physical models in the last 25 years or so. At first, emergence of **high-speed CNC** milling machines in various sizes allowed model makers to fully utilise its capabili-

Second is the emergence of two-dimensional computer-controlled **laser cutters**, which operate on the same drafting principle of a graphic plotter. This allowed for quick machining of 2D shapes in both opaque and transparent materials. It has been

IGES is the earliest format and is still a popular, though

which then could be automatically converted into 3D data.

the latest multicolour 3D printers with high resolution capabilities.

<sup>5</sup> https://www.cadcrowd.com/blog/top-file-formats-for-sharing-3d-and-2d-cad-designs/

reliable for 3D printing.5

**Figure 12.**

*CAD sketching (source: surfaced.com).*

**4. Rapid physical models**

ties for model making for industrial design.

*DOI: http://dx.doi.org/10.5772/intechopen.88788*

<sup>4</sup> https://www.mmsonline.com/articles/key-cnc-concept-1the-fundamentals-of-cnc

*Rapid Physical Models: A New Phase in Industrial Design DOI: http://dx.doi.org/10.5772/intechopen.88788*

**Figure 12.** *CAD sketching (source: surfaced.com).*

*Design and Manufacturing*

realise models of complex/sophisticated form is increased. This shift from simple methods to complex process in model making has been accompanied by technological advancement, mainly in computer aided design (CAD) and computer numerical control (CNC) which are the keys to today's model making techniques such as high speed CNC, laser cutting and 3D printing. The availability of accurate 3D data pro-

and President of CNC Concepts Inc., CNC offers three distinct benefits, the first being the **reduced skill level** due to improved automation. The second benefit is the **consistency and accuracy** of the parts that are produced and third benefit is the

During the starting period of model making during the last century, the emphasis laid on the skill of the model maker. Those who took up this profession were craftsmen or, many a times, the designers. The dimensional accuracy of the model. as well as the shape, form and finishes depended on the skill level of the model maker. With the advent of 'rapid' methods this skill was embedded in the machine and method itself and the model maker has more of a technician's role in the model making process. How did this change happen? This is best explained in the next

The most significant progress in product design and development occurred with the advent of computer aided design (CAD) in the 1960s. CAD as an idea and working prototype was derived from the idea of CNC (which was developed by Dr. Patrick J. Hanratty in 1957) and first developed by Ivan Sutherland at MIT as SKETCHPAD which showed the capabilities of computers with display in technical drawing. The full potential of CAD as a three-dimensional development tool was realised through

<sup>4</sup> https://www.mmsonline.com/articles/key-cnc-concept-1the-fundamentals-of-cnc

Founder

duced by CAD software enables reliable CNC. According to Mike Lynch,4

**flexibility** to change to many different parts or models.

section on computer aided design (CAD).

*Progress of physical model making for industrial design.*

**134**

**3.1 Enter CAD**

**Table 3.**

software such as Pro/Engineer, UniGraphics, CATIA in the 1980s. With CAD, industrial designers were able to design in 3D and define the details on the surface and the various features within the 3D environment, which then becomes 3D data that is utilised by any CNC controlled system to machine or manufacture the design with a high level of fidelity in terms of dimensions and details. Today industrial designers use very sophisticated software such as Autodesk 360 and Rhinoceros, which allows for not only 3D data transfer for model making, but also for 'photo-realistic' renderings and to transfer the model to engineers for detail development. **Figure 12** shows the high level of flexibility that CAD offers including visualisation in sketch form which then could be automatically converted into 3D data.

Having 3D data that is transferrable with high reliability of the design concepts is the first step towards the realisation of rapid physical models. Many formats for transferring reliable 3D data have been developed, the most common ones being IGES, STEP, STL and OBJ. In the field of rapid model making, IGES and STEP are predominantly used in high speed CNC while STL and OBJ formats are the most reliable for 3D printing.5 IGES is the earliest format and is still a popular, though more for 2D graphics and object rather than for 3D format. STEP is perhaps the first true 3D file convertor which relates to ISO 10303 and is widely used to transfer 3D data created by different CAD software platforms as well as transfer data to CNC programmers. STL is pure 3D information on geometry and shapes and does not hold any information colour, textures, etc. OBJ file format stores both form (geometry and shape) data as well as colour and texture information and is very useful in the latest multicolour 3D printers with high resolution capabilities.
