1. 6 Establishing Functions
The Function Analysis Method (FAM)

2. What is FAM?
FAM is a means of establishing the problem level at which a designer is to work (a boundary around a coherent sub-set of functions) by considering the essential functions that a solution type will satisfy.

3. What is the aim of FAM?
Establish the functions required of a new design.
Establish the system boundary (level of the design problem under consideration.

4. Procedure of FAM
Express the overall function for the design in terms of conversion of inputs into outputs. See Fig. 30, the Overall Black Box function Model.
Break down the overall function into a set of essential sub-functions. The sub-functions comprise all the tasks to be performed inside the black box.
Draw a Block Diagram that is transparent, i.e. shows the sub-functions & their interactions. See Fig. 31, the Transparent Box Model.
Draw the system boundary; it defines the functional limits for the device to be designed.
Search for appropriate components to perform the sub-functions and their interactions. Many alternative components may perform the identified functions.

5. Example 1 Animal Feed Bagging & Delivery System
FAM is particularly relevant in the design of flow-process systems, as that in Fig. 32.
The company wanted to reduce the relatively high costs involved in the existing method shown in Fig. 32.
A designer proposed the following four alternatives (as in Fig. 33) for the overall function (broader formulation) of the problem:
Transfer of feed from mixing bin to bags stored in warehouse
Transfer of feed from mixing bin to bags loaded on truck
Transfer of feed from mixing bin to consumers’ storage bins
Transfer of feed ingredients from source to consumers’ storage bins
Each of the above broader formulation of the problem suggests different kinds of solution leading perhaps to the elimination of the handling, storing and loading sub-functions.

6. Example 2 Design of Automatic Tea-maker
The design procedure started in the objectives tree method (Fig. 26).
The overall function box is shown in Fig. 36.
Fig. 37 gives three alternative processes for tea brewing.
After considering these various alternatives by which the overall function can be achieved, the designer settled on the process shown as a flow diagram of sub-functions in Fig. 37(a).
Various necessary auxiliary functions then became apparent, particularly to do with controlling the heating and brewing processes (as shown in Fig. 38 that shows the function analysis diagram and Fig. 26 of objectives).

7. Example 3 Domestic Washing Machine
The overall function of such a machine is to convert an input of soiled clothes into an output of clean clothes, as shown in Fig. 40.
Further stages can include: conversion of clean wet clothes into clean dry clothes then pressing and sorting.
The above 3 stages are represented in Fig. 41(up).
The essential sub-functions, together with the conventional means of achieving them, are:
Essential sub-function Means of achieving it
Loosen dirt Add water & detergent
Separate dirt from clothes Agitate
Remove dirt Rinse
Remove water spin
Dry clothes Blow with hot air
Smooth clothes Press
Block diagram with main and secondary inputs & outputs in Fig. 41.
Development of washing machines has progressively widening the system boundary as shown in Fig. 41.