Flow diagrams, travel charts & string diagram is a tools of method study to analyze process overview in a layout mode and identify opportunities for improvement. Generally, each tool of method studies like OPC, FPC, and Two-handed chart suggests the study of process overview in a line diagram mode. In this article, you deeply learn to identify improvement opportunities in a layout mode so observers get a more clear idea about improvement.

After identifying the major gap in processes with the help of a flow diagram, travel chart & string diagram, applied different lean manufacturing tools for internal process optimization like Kaizen, Single minute of exchange dies, 6 ‘S’, and many more.

What do you learn from this article?

• Basic understanding of Flow diagrams travels charts & string diagrams.
• Practical steps for implementing flow diagram, travel chart & string diagram.
• Practical examples of each chart.

Flow Diagram

The flow diagram is a pictorial representation tool of method study to get a more clear idea of interdepartmental movement. The flow diagram is drawn based on a scaleable layout. One workstation to another workstation movement is defined based on a line and arrow to give the direction of process movement. The flow diagram is representing multiple movements with different colors of line.

When the organization is planning to layout modification then in initial condition flow diagram is a very helpful tool to give a basic overview of entire processes. To measure movement between workstations and identify improvement opportunity flow diagram helps to represent processes visually.

Practical steps for flow diagram drawing & Implementation.

• Draw a scalable layout on appropriate software like AutoCAD, and NX-cad, and also you can make it in Microsoft excel.
• Indicate departmental movement mentioned with arrow lines.
• Analyze the cross and major movement between workstations.
• Identify opportunities for improvement.
• Draw a proposed layout similar to the current layout & shown the proposed movement between workstations.
• Implement the proposed layout.

Review below-attached flow diagram is one of the manufacturing processes. The left side material inlet & go to raw material storage then the movement of each workstation is represented with an arrow line. Review the internal movement of current processes based on the flow diagram and think of a proposed solution to minimize interdepartmental movements.

Travel chart

A travel chart is a basically tool of method study to measure department movement in a table form. This chart does not represent in layout mode similar to the flow diagram & string diagram. A travel chart is the easiest tool of method study & quickly developed. Review the attached tabular diagram of the travel chart. 

The travel chart identifies movement between workstations. The distance mentioned in meter, column & raw mentioned department to measure distance.

Practical steps for travel chart implementation.

• Identify a number of departments to measure movement.
• Department name fills in row and column.
• Measure the distance of departmental movement & fill the travel chart table.
• Focused on max. distance of departmental movement.
• Plan to minimize departmental movement based on improvement ideas.
• Conduct the travel chart study in the proposed method.
• Measure saving, if reduced movement between departments then standardizes the proposed method.

String Diagram

The string diagram is similar to the flow diagram but the only difference is to use of string for measuring the distance between workstations. A string diagram is also pictorial information & drawn in a scale-able mode. On printed scale-able diagram string attached manually based on the flow of manpower. To capture total movement, measure the length of the string used in the string diagram.

Generally, a string diagram is used to easily capture repetitive movement as well as patterns of worker movement.

Practical steps for string diagram drawing and implementation.

• Draw a scaleable layout on appropriate software like Auto CAD, and NX CAD, and also you can make Microsoft excel.
• Take a printout and define the scale of movement.
• On each workstation attached is a pin where the worker’s movement starts.
• Attached string on the pin as per the movement of workers.
• Measure the length of the string to capture the worker’s movement.
• Analyze the cross and major movement of workers between workstations.
• Identify opportunities for improvement to minimize movements.
• Draw a proposed layout similar to the current layout & shown the proposed movement between workstations.
• Implement the proposed layout.

Review the attached image of the string diagram. An example is considered similar to a flow diagram but chart representation is different. As per discuss earlier mention blue circle is a pin and the black line is a string. For easy understanding, I developed a string diagram in excel but practically developed it on a pin board with the help of pin & string.

To measure movement between each department, measure the length of the string. Review repetitive & major movements between workstations & identify improvement opportunities and developed proposed layout.