Process Components
Operation
An act that transforms one or more attributes of an entity or set of entities. Examples include manufacturing, services, transportation, or projects. An operation will require the use of one or more resources in order to perform the transformation. These resources include raw materials, subassemblies, components, labor, machines, information, intelligence, energy, fuel, etc.
Queue
A set of objects, tasks, or other things waiting for something, typically an action to be processed in a production system.
Stock
A set of completed transformations or entities. As such, the entities in stock are immediately ready to satisfy demand. Since Demand is a flow and the transformation Process is a flow, there will always be a stock between demand and transformation. However, since the demand for services is always backordered, such a stock will always be empty but will nonetheless function as a stock.
Processes and Flows
Process
A set of one or more operations designed to transform a set of entities into another form to achieve a particular purpose. A process may result in production of a physical product or completion of a service. As a standard rule, the sequence of production mapping begins with a Stock, followed by an Operation, and can conclude with either a Queue or another Stock. A complete sequence, however, always concludes with a Stock.
Flow
A flow is a collection of production or service routings or a collection of demand streams. A flow represents materials or resources moving through the transformation process, A flow is described by a rate. The measure of a flow is some unit or task per period of time. A flow can be a set of operations called a process that accomplishes transformation. A flow can also be a set of individuals creating the demand for the transformed entities. The rate of flow for a process is called its throughput.
