1. QUAN 6610 Flow Time Analysis (T)
Chapter 4
Flow Time Analysis (T)
I = R x T
Chapter 4
Flow-Time Analysis
Chapter 5
Flow Rate and Capacity Analysis
Chapter 6
Inventory Analysis
Based on Anupindi, et al, MBPF (2e)
Flow Time

2. Process Flow Time Flow time affects delivery response time.
Short flow times reduce the inventory.
Shorter flow time in the development process enables a company to get to market quicker giving a competitive advantage.
Can minimize production start to gain market information, avoid product obsolescence and minimize inventory.
Results in fast feedback and correction of quality problems.
Flow time is an integrative measure of overall process performance.

3. A process flowchart is a graphical representation of the five process elements: inputs and outputs, flow units, network of activities, resources allocated to activities and information structure. 3 1 2 4 6 7 8 5
Direct measurement and indirect measurement method.
Example 4.2

4. Determining the critical path
4.3 Theoretical Flow Time
Determining the critical path
Theoretical flow time is the minimum amount of time required for processing a typical flow unit without any waiting.
Example 4.4

5. Example 4.5
Flow time = Theoretical flow time + Waiting time

6. Value-adding and Non-value-adding
Flow time = value-adding flow time + non-value-adding flow time
Rework, Visits and Work Content
Example 4.6 | Table 4.4
Work content = activity time * average number of visits

7. Flow time efficiency = Theoretical flow time / Average flow time
QUAN 6610
Flow time efficiency
X-ray VOH Example 4.7
Flow time efficiency = Theoretical flow time / Average flow time
Most time inefficiency comes from waiting: E.g.: Flow Times in White Collar Processes
Flow Time

8. Levers for Reducing Flow Time
QUAN 6610
Levers for Reducing Flow Time
Decrease the work content of critical activities
work smarter
work faster
do it right the first time
change product mix
Move work content from critical to non-critical activities
to non-critical path or to ``outer loop’’
Reduce waiting time.
Flow Time

9. QUAN 6610
Value Added vs. NVA Time
“Just track any work items as it flows through the process and classify the time into one of three categories: (1) value-added work, (2) waste that is required for business reasons, and (3) delays/waste. Then draw a timeline and mark off the time segments for each of these categories. In the example shown, the value-added work (shaded above the centerline) shows the buyer in this purchasing organization is only working the order for 14 minutes of the 4 day cycle. The majority of the time, delineated by white space, is idle queueing time.”
Lean Six Sigma by George, et al.
Process Capacity

10. QUAN 6610
Source: Lean Learning Center, Value Stream Mapping Course Notes.
Process Capacity

11. QUAN 6610
Source: Lean Learning Center, Value Stream Mapping Course Notes.
Process Capacity

13. source: Finch, Operations Now

14. source: Finch, Operations Now

15. source: Finch, Operations Now

16. source: Finch, Operations Now