A coffee roaster FSD would be constructed as another illustrative example. Some companies have been attempting to cash in on the increase in interest in quality coffee. No company has designed and marketed a completely satisfying roaster for the home market. As part of an effort to develop a coffee roaster for use in a house, a FSD would be developed. Step 1 Understanding Functions – Done! – Step 2 Creating the Black Box Model – Products Basic Function: Roast Beans – Input Flows – Green Coffee Beans – Electricity – Desired Roast Level – Start Signal – The desired roast level is how dark the user would like the roasted beans.
Different roast levels will produce coffee with different flavors. Output Flows – Roasted Coffee Beans – Chaff – Unpleasant Odor – Noise – Heat – Chaff is a thin skin which comes off of the coffee bean during roasting. The chaff must be separated from the roasted beans before the beans are ground. Roasting beans produces an unpleasant smell that must be contained or eliminated. Grinding coffee produces the pleasant odor that numerous people associate with coffee houses. Black Box Diagram – The black box diagram for the roaster is shown in figure 9. Step 3 Tracing the Input Flows – Note that the functions Heat Beans and Agitated Beans are shown in parallel because they must happen simultaneously.
Some functions might need to be added. Always check the final FSD against your original black box model. Step 5 Assembling the tracks and Selecting the Boundary – Do the outputs and inputs of your final FSD agree with the outputs and inputs of your original black box diagram? Yes. What hypotheses were made by your choice of input flows output flows and system boundaries? At the Roaster example, the input Electricity assumes that the roaster will plug into a household outlet.
Are these assumptions appropriate for your project? Are they documented in your design brief? The answer would depend on the project and the design brief. Are all the harmful, unintended or undesirable output flows documented? Yes, heat, noise and chaff are included in the FSD. Do your assumptions align with your design brief? All assumptions should be explicitly documented in the design brief. Does the boundary of the FSD communicate the scope of the project described in the design brief? The answer depends upon the design brief.
Are all Functions solution neutral? Yes, all functions describe what must be done not how a function would be accomplished. Can any one of the functions be broken down into simpler functions? No, each function is atomic. Would the user benefit from output signals that confirm correct functioning of the device? Perhaps a signal that indicates when the ground coffee is ready to be removed from the machine will be useful.