Processes, Inputs, and Outputs
Each system has inputs, outputs, processes, constraints and mechanisms. A process is an action that transforms given inputs into outputs under certain constraints or restrictions and with the aid of some mechanisms. For example, the process of making coffee by a coffee maker can take inputs such as coffee, filter, water, and electricity, and result in outputs such as coffee, used filter, used coffee and grounds.
Constraints and Mechanisms
The constraints can be size of the coffee maker and the quantity of coffee and water available, and the mechanism may be for someone to pour the coffee grounds into a filter and insert into the coffee maker, pour water into the coffee maker and turn on the coffee maker, and the coffee maker equipment itself. Sometimes outputs can result in feedback. For example, the quality of the coffee made can indicate which ingredient (water or coffee) should be controlled next time to produce better coffee. The input-output diagram for the coffee making process is shown in the figure below.
Identifying inputs, outputs, processes, constraints, and mechanisms of a system will help to understand the system and manage it better. For example, if one of the environmental goals of the coffee maker system is to reduce waste or increase efficiency, then the inputs, outputs, process, constraints, and mechanisms can be analyzed to find the best way to accomplish the goals. The paper filter could be replaced by a reusable metal filter to eliminate the manufacture and use of paper filters, or a better approach could be devised to discard used coffee grounds.