The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

Process structure

The Quality Toolbook > Processes > Process structure

Actions | Inputs and outputs | Suppliers and customers | Nesting

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Improving processes means understanding their structure, both internally and in the interactions with other processes. This section gives a basic description of some key elements.

Actions within a process

Within a process, the 'series of actions' can be broken down into two types:

What makes the process systematic is that these actions are not performed randomly, but in a predefined sequence. The most common tool to show this sequence is a Flowchart (see below), which uses different symbols to distinguish the different types of action.

Fig. 1. Basic flowchart structure

Inputs and outputs

The goal of a process is usually the transformation of a set of inputs into a set of outputs, as shown below. (in practice, there are additional 'inputs' which are not transformed, such as machines, specifications, etc.).

Fig. 2. Inputs and outputs

This presents a problem when drawing diagrams of processes, as arrows may show either the sequence of actions, as in the flowchart, or the inputs and outputs, as above. The approach that tools usually take is to do one or the other, but not both.

Suppliers and customers

The inputs to a process are the outputs from a previous or supplier process. The outputs of a process form the inputs to a later customer process. Processes thus link together to form chains of supplier and customer processes, thus:

Fig. 3. The chain of customer and supplier processes

In practice, there can be many customers of a process, as producing a faulty output may not only cause problems for the following process, but also (if the output is passed on in any way) for the other indirect customers further down the chain. Thus the customers of a design engineer include not only the production engineer, but production line workers, sales people and so on through to the end customer, as a bad design will affect all these people.

Nesting

Each process may itself contain other processes, which in turn may contain further processes. This nesting can make processes easier to understand at different levels, as shown below.

Fig. 4. Nesting into sub-processes

Thus the operation of an entire company may be considered as a single process, with inputs from suppliers, banks, etc., and outputs to customers, shareholders, etc. This may then be broken down into the major sub-processes, such as purchasing and manufacturing, each of which can be iteratively decomposed to an appropriate level (typically to individual roles). This can then be used in the analysis of company, department or personal processes, investigating how well processes interact and contribute to real customer needs.

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