4. flow-time analysis flow time 1-introduction based on the book: managing business process flows
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4. Flow-Time Analysis
Flow Time
1-Introduction
Based on the book: Managing Business Process Flows
4. Flow-Time Analysis
Competitive Advantages of a short flow time
Short response time both in production and in product design.
More responsive to changes in customer preferences and
technological advancements.
Delayed differentiation, Postponement.
Moving from Made To Stock towards Make To Order.
Lower inventory costs, due to Little’s Law.
Flow Time - Introduction 2Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Direct Method of Measuring Flow Time
Randomly sample flow units over an extended period of time. Measure the flow time for each flow unit from entry to exit. Compute the average of flow times.
During a given month, a sample of 50 applications was taken The average flow time = 20.8 working days.
Flow Time - Introduction 3Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Indirect Methods of Measuring Flow Time
Count the number of units produced over an extended period of time.
R = number of units produced / duration of time period . Count the number of units of inventory at random points during the
time period. Compute the average inventory (I). Compute flow time T =I/R
200 applications processed during 20 days; average throughput of R=200/20 = 10 applications per day. The number of waiting applications counted at 4 random points during these days added to 860. I= 860/4 =215.
T = I/R T = 215/10 flow time is 21.5 days vs 20.8Flow Time - Introduction 4Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Process : Network of activities performed by resources
1-2. Flow unit (input/output): Unit of analysis– Level of detail
3. Network of Activities & Buffers
- Define Process Boundaries
- Activities with activity times
- Buffers with waiting times
- Routes: precedence relationships (solid lines) with throughputs
4. Resources & Allocation
- Who does what?
5. Information Structure & flow (dashed lines)
Key for capacity analysis
Process Flow Chart
Flow Time - Introduction 5Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Flowcharting
ActivityBuffer
Physical flowEvent
Information flow
See the total process; a systems view Define flow units and process boundaries Include only the key steps Clarify the level of detail needed. Processes can be
broken down into sub-activities. On the other hand, cascading allows several activities to be combined in a single sub-process
Depicts resources required to carry out activities Identify the processes that need attention (weak
points)
Decision
Flow Time - Introduction 6Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Wondershed Inc: Narrative Representation
1. Separate the roof and the base sheets
2. Punch the base
3. Punch the roof
4. Form the base
5. Form the roof
6. Weld the base
7. Assemble base and roof
8. Inspect
Flow Time - Introduction 7Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
End
Wondershed Inc. : Schematic Representation
StartSeparate
Sheet
Punch base
Punch roof
Form base
Form roof
Wed base
InspectAssemble
StartActivity
AActivity
BActivity
CEnd
Flow Time - Introduction 8Ardavan Asef-Vaziri, June, 2015
Buffer Activity
4. Flow-Time Analysis
Theoretical Flow Time
Activity Time: The time required by a typical flow unit to complete the activity. Tp for a single activity.
Theoretical Activity Time. Tp net of any waste inside Tp
Unless stated otherwise, we assume that an activity cannot be broken down into smaller activities that can be executed in parallel. What does that mean???
Pure Theoretical Flow Time: The minimum amount of time required for processing a typical flow unit without any waiting and without any waste inside Tp.
Theoretical Flow Time: The minimum amount of time required for processing a typical flow unit without any waiting.
Flow Time - Introduction 9Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Critical Path
Theoretical flow time of each path in the process flowchart = sum of the activity times of all activities on that pathCritical Path: the longest path Critical Activities: activities that lie on the critical pathTheoretical flow time of the process = Time of the theoretical
critical path
Activity Time 2Activity Time 1 Activity Time 3
Activity Time 5Activity Time 4 Activity Time 6
Sequential Activities
Sequential Activities
Parallel Activities
How many Paths?
Activity Time 2Activity Time 1 Activity Time 3
Activity Time 2Activity Time 1 Activity Time 3
Flow Time - Introduction 10Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Wondershed Inc. Theoretical Flow Time
Path 1 (roof) Start 1 3 5 7 8 End 10 +20 +10 +10+30 = 80 minPath 2 (base) Start 1 2 4 6 7 8 End 10 +25+5 + 10 +10+30 = 90 minTheoretical Flow Time = 90 min
Activity Activity Time (Work Content)
1 Separate 102 Punch the base 253 Punch the roof 204 Form the base 55 Form the roof 106 Weld the base 107 Assemble 108 Inspect 30
Flow Time - Introduction 11Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Wondershed Inc. Flow Time
Path 1 (roof) Start 1 3 5 7 8 End 30 + 110 + 85 + 55 + 105 = 385 minPath 2 (base) Start 1 2 4 6 7 8 End 30 + 70 + 40 + 70 + 55+ 105 = 370 minFlow Time = 385 min
Activity Activity Time (Work Content) Waiting Time Flow Time
1Separate 10 20 302Punch the base 25 45 703Punch the roof 20 90 1104Form the base 5 35 405Form the roof 10 75 856Wed the base 10 60 707Assemble 10 45 558Inspect 30 75 105
Flow Time - Introduction 12Ardavan Asef-Vaziri, June, 2015
4. Flow-Time Analysis
Flow Time Efficiencies in White Collar Processes
Flow Time Efficiency = Theoretical Flow Time / Flow
Time
Flow Time Efficiency = 90/385 = 23.4%
Flow Time - Introduction 13Ardavan Asef-Vaziri, June, 2015
Industry Process Average Flow Time
Theoretical Flow Time
Flow Time Efficiency
Life
Insurance
New Policy
Application72 hrs. 7 min. 0.16%
Consumer
Packaging
New Graphic
Design18 days 2 hrs. 0.14%
Commercial
Bank
Consumer
Loan24 hrs. 34 min. 2.36%
HospitalPatient
Billing10 days 3 hrs. 3.75%
Automobile
Manufacture
Financial
Closing11 days 5 hrs 5.60%