Process flow diagram

A simple visual approach to map the different stages in a process and to identoify areas for improvement.

A Process Flow Diagram is a paper-based tool which represents a series of activities as a diagram. It can be used by improvement teams with little formal training.

Why is it used?

To identify weaknesses in existing process arrangements and to highlight improvement points.

When is it used?

In early diagnostic work. Finding out how the process currently works is an important part of the data collection phase, so it is usual to construct a Process Flow Diagram as an initial activity. More detailed process flow analysis can be used later on, and the technique forms a key element in business process re-engineering.

How is it used?

Every business activity can be viewed as a process. In simple terms, a process is the transformation of inputs into outputs. When looking to make improvements it is useful to be able to view activities as a formal process.

The aim of a Process Flow Diagram is to lay out clearly the step-by-step flow of a process by tracking the flow of material, information or a service through all its steps. In doing this the diagram:

• Helps a wide and sometimes unfamiliar audience to picture the steps of a process and clarifies misconceptions about how the process actually operates.
• Helps to determine and position actions that will prevent problems, as well as identifying major sub-processes which may require their own process definition.
• Provides a reference for the handling of corrective action or process improvement.

Once the steps in the process are clear, simple analysis can reveal opportunities for improvement.

Like any versatile tool, there are many variations of Process Flow Diagram. The example used here is the 'classical example'. Each activity is placed in one of the following five activity categories.

Operation — the main steps in the process
Inspection — a check on quality or quantity
Transport — movement of people, material, information, etc
Storage — a controlled storage such as filing, which is not a delay
Delay — a temporary storage, delay or hold up between consecutive operations

Since the only category that adds value is the Operation, the objective is to redesign the process to eliminate or minimise the other four. The symbols used to represent these activities are shown in Figure 1.

Figure 1: common symbols used for detailed flow diagrams

There are four steps in constructing the Process Flow Diagram:

1. Identify and confirm the scope of the process that is under review, paying particular attention to the start and finish points.
2. Determine and list the steps required to carry out the process. Each action step should be named as a phrase containing a verb and a noun.
3. Sequence the steps correctly and mark the activity category with a dot.
4. Join the dots and calculate the totals.

It is important that the diagram reflects the true situation as closely as possible, and that the group constructing it reaches consensus. An example is given in Figure 2.

Figure 2: a Process Flow Diagram showing an administrative task

Note the summary line showing eleven transportation activities and seven delays, all non value adding!