The charting of work flows, working processes, systems and procedures is a useful way of recording the essential features of a work situation for subsequent analysis. Process Charts are one of the simpler forms of workflow charting and are still in regular usage but are less common than they once were (see Process Mapping). This is unfortunate since it was the ubiquitous nature of the process chart that made it a common "language" between different groups of people and across different industries. A variety of process charts has been designed to meet the needs of a particular level or stage of analysis; they can be used at a detailed level (recording activity at a specific work station or workplace), but also at the wider system, process or procedure level. The different kinds of process chart share a common core set of symbols, though some have additional symbols for specific and specialised process steps. The common symbols (of which there are only five) were first promulgated by the American Society of Mechanical Engineers and have become known as the ASME symbols.
These symbols are simply linked together in a vertical chart representing the key stages in a process; it is usual to place a commentary in an adjoining column recording contextual/environmental information. e.g. against a Transport symbol would be recorded, start of journey, end of journey, distance and mode of transport. The simplest form of process chart is known as an outline process chart and records an overview or outline of a process. Only those steps of a process that can be represented by the ASME symbols of operation and inspection are recorded. An outline process chart is often a useful first step to identify key areas of concern before recording (part of) the process in more detail. In a "full" process chart, where all symbols are used, it is common to chart the process from the "viewpoint" of the material being processed, the worker carrying out the work or, less commonly, a piece of equipment. Thus, the same symbols can be used in different ways. As a simple example, a piece of equipment can be represented on an equipment-type flow process chart as a delay because it is not in use; while a material-type flow process chart of the same process would show the material being transported to the next work station, and a man-type chart could show the operator involved in another operation on another machine. The chart to be used may be determined by the purpose of the investigation or by the relative costs involved in the process - a highly capital-intensive process may focus more attention on the equipment being used. Process charts may also be used at a more micro level of analysis. An example is the two-handed process chart which records the motions performed by both hands during a task. The sequence of motion of each hand is charted using the same symbols as before. There are slight changes to the meaning of the symbols, however. The delay symbol is used to indicate that the hand is waiting to carry out its next task. The storage symbol is used to indicate that the hand is holding on to a piece of material or a document. Two-handed process charts are usually drawn on a pre-formatted diagram. Their use has generally been superseded by the analyses involved in the use of low level pre-determined motion times systems. back to Knowledge Bank
Also known as Flow Process Chart. Variants include Process Chart, Flow Diagram and Spaghetti Diagram. A process sequence chat is a symbolic representation that illustrates the sequence of activities within a process. It is used to record the activities that make up a process to determine which steps add value and which do not. It is preferred over other process mapping techniques when the process is sequential in nature and contains no or few decision points. Activities in these types of charts can be any operation, inspection, storage or transportation actions that are carried out by an individual, a team, a machine, a system, or a combinations of all. A useful feature of these charts is that they can be drawn up as the process is happening, thus providing an accurate description of the process. By observing and recording, you can for example follow a part, noting how and when it is operated, moved, inspected and stored. Later on and when analyzing the process, some steps become obvious candidates for improvement, such as non-value-added activities, long delays and excessive transportation.
There are three types of process sequence charts based on what is being charted:
Activities in a process sequence chart are recorded along a vertical or horizontal line using common symbols and descriptive words. These symbols have been accepted by many Lean practitioners and organizations. Other symbols can be used as needed. The following is a brief explanation of the common five categories used in process sequence chart along with examples for each of them.
OPERATION – Produce, add, change, or process something.
INSPECTION – Checking of items to ensure correct quality and/or quantity.
STORAGE – The storing of something until later time.
TRANSPORT – The movement of people, materials, or other items between locations.
DELAY – The temporary waiting of something or somebody.
Care should be taken when choosing the right category, as a delay of a machine could be an inspection made by an operator or a transportation activity.
A good practice is to chart the present process as well as the future process in order to drive change and continuous improvement. A typical approach is to chart the present process first and then propose the improvement on a second chart.
Improvements can be made by reducing the number of activities, reducing the time each activity takes, or reducing the distance of travel for the transport activities. Thus, it is important to tracks performance measures such as cycle times, error rates, and distance travelled.
The following example illustrates a process sequence chart prepared for an egg tray production line, which is a material-type process sequence chart. Note that the time it takes to perform each activity can be written under the symbols. Process Chart
A process chart presents the process activities and the related information in the form of a table. It allows recording further information about each process activity such as error rates, time and distance. These information can help later in estimating key performance metrics, including:
The following example shows a process sequence chart and a process chart for processing an invoice after received by the supplier. The process begins after receiving the invoice and ends with paying the supplier. The following table is the process chart summary which is useful to estimate key performance indicators.
Process sequence charts and process charts are sometimes drawn up in conjunction with other tools such as flow diagrams and opportunity maps.
There are many tools that can help you to chart your processes. One of the simplest ways is to use this process chart template.
Other Formats If you want to use the following three documents in your training courses, the PPTX versions are available to buy from our Shop page.
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What is the method analysis chart that describes the overall sequence of operation movement inspection delay and storage?
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