\chapter{Embodiment Design}
In the previous two chapters, different devices that perform the requirements were
derived by using the morphological chart idea.  The concepts were sketched, not
in great detail, but in a way that presents the major functions that compose the
device. These concepts were then
evaluated based on three different stages.  The first stage involves subjecting the
concept to the specification table, if it passes the demands then a feasibility
test is conducted.  If the concept passes the first two stages, then it will be
subjected to relative evaluation based on the Pugh method.  
In this stage of the design process, the design team starts what could be called
 the "embodiment design stage."  The word "embody" means, to give something a
 a tangible expression.  

This chapter
discusses the presentation of the concept(s) that pass the evaluation criteria. 
The idea of presenting the information through drawings was introduced when different
concepts were generated from the morphological chart.  The sketches that present
the concepts are not detailed: they simply provide enough information to demonstrate the combination of
the different function mechanisms that produce the concept.  The following figure 
shows four conceptual sketches of a device that removes leaves from lawns.

\def \epsfsize#1#2{0.15#1}
\begin{figure}
\epsffile{../figures/9-1.eps}
\caption{Conceptual Sketches}
\end{figure}
 

It should be reemphasized that the design process is an iterative process. This
means that if additional refinements are found necessary, after the skeleton
sketches or while in the evaluation stage,
 the designer should iterate back to the concept phase and possibly generate new
 concepts. The drawback of this process is that it takes time, but that time should be initially
 implanted in the scheduling of events.
 
 In the world of engineering, information needs to be passed on through drawings. The analysis,
 manufacturing and assembly of the product is based on drawings.  The following
 section discusses the type of drawings that are required by the designing
 team.


\section{Product Drawings}
In the design process, drawings may be used to serve the following objectives: 
\begin{enumerate}
\item Drawings are the preferred form of data communications in the world of
engineering.  
\item Drawings are used to communicate ideas between the designers and between the designers and
manufacturing personnel. 
\item Drawings simulate the operation the product.
\item Drawings are used to check for the completeness of the product.
\end{enumerate}


There are different types of drawings that can be used at different levels, these
include:
\begin{enumerate}
\item {\bf Sketches (Layout Drawing):} Sketches are generated during the conceptualization stage of the design process.
Different mechanisms of each function or sub-function are first sketched.  These
sketches are then used to build devices. 
 These sketches serve the purpose of presenting the completeness of the
 device. These sketches are working documents that
support the development of the major components and their relations.  
They are made to scale, but only the important dimensions are shown in the
layout.  Tolerances are usually not shown unless they are critical.  This form
of drawing is needed in the analysis.  When an individual component is analyzed,
a sketch presents the relation of this part with its surroundings.
\item {\bf Detail Drawings:}  As the product evolves, a detail of individual
components develop.  A typical detail drawing is shown in the figure.
\ref{detail}

\def \epsfsize#1#2{0.15#1}
\begin{figure}
\epsffile{../figures/9-2.eps}
\caption{Typical Detail Drawing}
\label{detail}
\end{figure}

The important characteristics of a detail drawing include:
\begin{enumerate}
\item All dimensions must be tolerances.
\item Materials and manufacturing detail must be clear and presented in specific language.
\end{enumerate}
These drawings are made using a CAD system, such as Pro/E.   
\item {\bf Assembly Drawings:} The goal of the assembly drawing is to show how
components fit together.  Figure \ref{assem} shows a typical assembly drawing. An assembly drawing has the following characteristics:


\def \epsfsize#1#2{0.15#1}
\begin{figure}
\epsffile{../figures/9-3.eps}
\caption{Typical Assembly Drawing}
\label{assem}
\end{figure}

\begin{enumerate}
\item Each component is identified with a number referenced to a list of all
components.
\item Necessary, detailed views are included to explain information that is not
clear in other views.

\end{enumerate}

\end{enumerate}

\section{Bill of Material}
The bill of material is an index of the parts that were used in the product.  A
typical bill of material is shown in the table below.  


\begin{figure}
\epsffile{9-4.eps}
\caption{Bill of Materials}
\end{figure}


The following 
information should be on a bill of material:
\begin{enumerate}
\item The item number: This is a key to the components on the assembly drawing.
\item The part number:  This is a number used throughout the purchasing,
manufacturing and assembly system to identify the component.  The item number
is a specific index to the assembly drawing, the part number 
 is an index to the
company system.
\item The quantity needed in the assembly.
\item The name and description of the component.
\item The material from which the component is made.
\item The source of the component.
\item The cost of the individual component.  This part will be kept for the
design team. 
\end{enumerate}

\section{Prototype}
  
The experimental phase of the engineering design requires the transformation of paper
drawings into hardware, which is constructed and tested to verify the concept's workability.

There are three construction techniques that are available for the designers, namely:
\begin{enumerate}
\item {\bf Mock-up}: This is generally constructed to scale from plastics, wood,
cardboard and so forth to give the designer a feel for his or her design.  It is often used
to check the clearance, assembly techniques, manufacturing consideration and
appearance.  This is the least expensive technique, relatively easy to produce 
 and can be used as a tool in
selling the idea to clients or management.  A solid model in the CAD system can often
replace the mock-up.  Mock-ups are usually referred to as a proof of concept
prototype.

\item {\bf Model}: The model relates the
physical behavior of the system through mathematical similitude.   The modeling is
usually referred to as proof of product prototype. There are
different types of models used to predict the behavior of a real system.
\begin{enumerate}
\item {\bf True} is an exact geometric reproduction of the real system, built to
scale and satisfying all restrictions imposed by the design parameters.
\item {\bf Adequate} is constructed to test specific characteristics of the design and
is not intended to yield information concerning the total design.
\item {\bf Distorted} purposely violates one or more design conditions.  This
violation is often required when it is difficult or impossible to satisfy the
specific conditions due to time, material or physical characteristics, and it is
felt that reliable information can be obtained through the distortion.
\end{enumerate}
\item {\bf Prototype}: This is the most expensive technique, and the one producing the
greatest amount of useful information.  The prototype is a constructed, full scale
working physical system.  The prototypes can be comprehensive or focused.  A
comprehensive prototype corresponds to a full scale, fully operational version of
the whole product. An example of the comprehensive prototype is the beta prototype, which is given
to customers in order to identify any remaining design flaws, before committing to its
production.  In contrast to comprehensive prototypes, focused prototypes correspond
to one or few of the product elements.  Examples of focused prototypes include foam
models used to explore different forms of a product. 
\end{enumerate}
\section{Example: Automatic can crusher}
Details of the chosen design are sketched, and a bill of material is generated
for that design.

\section{Problems}
\subsection{Team Activity}
Consider a regular stapler and a hole puncher. 
\begin{enumerate}
\item Draw a function tree.
\item Sketch the indvidual elements that were used to perform the functions.
\item Sketch the overall device (combine the elements to obtain the full
device).
\item Construct a limited bill of material for the device.
\end{enumerate}
  
