Page 278 - DMGT522_SERVICES MANAGEMENT

Unit 13: Performance Measurement in Services

13.5.1 Process Flow Diagram Notes

The process boundaries are defined by the entry and exit points of inputs and outputs of the
process.
Once the boundaries are defined, the process flow diagram (or process flowchart) is a valuable
tool for understanding the process using graphic elements to represent tasks, flows and storage.
The following is a flow diagram for a simple process having three sequential activities:
Figure 13.1: Process Flow Diagram

The symbols in a process flow diagram are defined as follows:

Rectangles: represent tasks to be perform.
Arrows: represent flows. Flows include the flow of material and the flow of information.
The flow of information may include production orders and instructions. The information
flow may take the form of a slip of paper that follows the material, or it may be routed
separately, possibly ahead of the material in order to ready the equipment. Material flow
usually is represented by a solid line and information flow by a dashed line.

Inverted triangles: represent storage (inventory). Storage bins commonly are used to
represent raw material inventory, work in process inventory, and finished goods inventory.

Circles: represent storage of information (not shown in the above diagram).
In a process flow diagram, tasks drawn one after the other in series are performed sequentially.
Tasks drawn in parallel are performed simultaneously.
In the above diagram, raw material is held in a storage bin at the beginning of the process. After
the last task, the output also is stored in a storage bin.
When constructing a flow diagram, care should be taken to avoid pitfalls that might cause the
flow diagram not to represent reality.

For example, if the diagram is constructed using information obtained from employees, the
employees may be reluctant to disclose rework loops and other potentially embarrassing aspects
of the process. Similarly, if there are illogical aspects of the process flow, employees may tend
to portray it as it should be and not as it is. Even if they portray the process as they perceive it,
their perception may differ from the actual process. For example, they may leave out important
activities that they deem to be insignificant.

13.5.2 Process Performance Measures

Operations managers are interested in process aspects such as cost, quality, flexibility, and
speed. Some of the process performance measures that communicate these aspects include:
Process capacity: The capacity of the process is its maximum output rate, measured in
units produced per unit of time. The capacity of a series of tasks is determined by the
lowest capacity task in the string. The capacity of parallel strings of tasks is the sum of the
capacities of the two strings, except for cases in which the two strings have different
outputs that are combined. In such cases, the capacity of the two parallel strings of tasks is
that of the lowest capacity parallel string.
Capacity utilization: The percentage of the process capacity that actually is being used.

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