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Lecture of
© Washington State University-20131
Introduction to TOC Topics
DBR, Critical Chain, Replenishment Overview
EM 530 Applications in Constraints Management
[email protected]://etm.wsu.edu/
James R. Holt, Ph.D., PEProfessor
Engineering Management
151
© Washington State University-2013 2
Angel eLearning Pages
© Washington State University-2013 3
Class Schedule
© Washington State University-2013 4
A Word about Angel
• Finding the Video/Archive Stream
Under the Communicate Tab
Elluminate Options
Today’s Lecture shows up
automatically
History of Recordings / Video Archives available
through search.
© Washington State University-2013 5
Elluminate Screen
© Washington State University-2013 6
Angel Calendar
• Calendar has current, past and future links to Video Conferencing.
Links here give the Live Video Conference in
Elluminate (during the time for class) or Archived
Video.
© Washington State University-2013 7
Communication Options
• Class Lecture Material in Angel Learning System:https:LMS.wsu.edu
• Elluminate Webstreamed Lectures (on links within Angel)
• Elluminate Communications Tab email.
• Dr Holt’s Email: [email protected]
• Skype at: HoltJames• Dr Holt’s Home Office:
• (540) 412-5315 (7:00 AM to 10:00 PM)
• Join the EM530-List: Visit Lists.wsu.edu, select <Join a List> and enter EM530-
List to join Send messages to [email protected]
© Washington State University-2013 8
Introduction to the Theory of Constraints
• Every system is a subset of a larger system.
• Within any complex system there is one constraint (or very few).
• Three main factors impact every system: InterdependenceStatistical Variation Behavior of individuals
• (Humans trying to deal with the first two factors)
© Washington State University-2013 9
Emphasis for this Course
• Physical Processes Process Flows
• Manufacturing, Paperwork, Service Processes Project Management Scheduling
• Single Project, Multi Project Distribution Systems
• Retail Model, Replenishment Supply Chains
• Cooperative and Non-Cooperative Members
© Washington State University-2013 10
Class Materials
• Texts: The Goal, Eli Goldratt Critical Chain, Eli Goldratt Project Management in the Fast Lane, Rob
Newbold Isn’t It Obvious? Eli Goldratt
• Software: Production Simulation,
Project Management Simulation, Lots of individual Games,
Excel based DBR model Scitor PS8.5
© Washington State University-2013 11
Individual Learning Experiences
• Simulations: Mostly on you own
• Games: Dice Game Job Shop Game Bead Experiment Project Management Games Supply Chain Game
• Research Searching known areas Searching publications
© Washington State University-2013 12
Process View of Systems
Input Process Output Input Process OutputInput Process Output
Larger Process
Input Process Output
© Washington State University-2013 13
System Complexity
• Division of Labor breaks down the linkages of complex systems into manageable chunks.
• Which is harder to manage? System A or B?
System A System B
© Washington State University-2013 14
Interdependence
100
The excess capacity at some links is of little value since there is usually some other factor that prevents links from functioning at maximum capacity
© Washington State University-2013 15
Operational Efficiency
• Work flows from left to right through processes with capacity shown.
Process A B C D E
RM FG
CapabilityParts 7 9 5 8 6per Day
Excellent Efficiency--Near 100%Chronic Complainer
Too Much Overtime
MarketRequest
11
© Washington State University-2013 16
Behaviors
• Workers will find a way!
Process A B C D E
RM FG
CapabilityParts 7 9 5 8 6per Day
MarketRequest
11
Both found ways to look busy and appear to have a capacity of 5 parts/day.
5 5
© Washington State University-2013 17
Behaviors
• Workers will find a way!
Process A B C D E
RM FG
CapabilityParts 7 9 5 5 5per Day
MarketRequest
11
Process A slowed to reduce building WIP
5 5
Process B doesn’t have a choice
© Washington State University-2013 18
Then Variability Sets In
• Processing times are just AVERAGE Estimates
Process A B C D E
FG
Reality 5+/-2 5+/-2 5+/-2 5+/-2 5+/-2
RM
© Washington State University-2013 19
What does an Average of 50% mean?
Process A B C D E
FG
Reality 5+/-2 5+/-2 5+/-2 5+/-2 5+/-2Prob: 0.5 0.5 0.5 0.5 0.5
• Half the time there are 5 or more per day at each process--Half the time less
RM
Two at a time: 0.25 0.25
Over all: 3.125% Chance of 5 per day
© Washington State University-2013 20
The TOC Approach to Solving Physical Problems
• The Five Focusing Steps Step 1. Find the Constraint Step 2. Decide How to Exploit the Constraint Step 3. Subordinate all others to the
Constraint Step 4. Elevate the Constraint Step 5. Warning!!! If the Constraint moves,
start over at Step 1.
© Washington State University-2013 21
1. Identify the Constraint
Process A B C D E
FG
• The Constraint is the “Drum” for total production (Identify can also mean ‘Select’)
RM
Reduced CapabilityParts 5 5 5 5 5per Day
© Washington State University-2013 22
2. Exploit the Constraint
Process A B C D E
FGRM
Reduced CapabilityParts 5 5 5 5 5per Day
Make sure there is work available for the constraint just-in-case (Buffer)
© Washington State University-2013 23
3. Subordinate All Else
Process A B C D E
FGRM
Real CapabilityParts 7 9 5 8 6per Day
Each process should operate at maximum capacity (Road Runner Work Ethic)
© Washington State University-2013 24
Prevent Over Production
Process A B C D E
FGRM
CapabilityParts 7 9 5 8 6per Day
Control release of material to the process at the rate the constraint demands (Rope). The Art of Subordination.
© Washington State University-2013 25
Protect Yourself to be Predictable
Process A B C D E
FGRM
CapabilityParts 7 9 5 8 6per Day
Protect from Variability in Receiving Protect from Variability in
Constraint
© Washington State University-2013 26
Step 4. Elevate the Constraint
Process A B C D E
FGRM
CapabilityParts 7 9 5 8 6per Day
When more capacity is needed than the constraint can produce, often it is necessary to increase the capacity of the constraint.
10
© Washington State University-2013 27
Step 5. Avoid Inertia
Process A B C D E
FGRM
CapabilityParts 7 9 10 8 6per Day
When the constraint moves, change your controls.
© Washington State University-2013 28
A better option,
Process A B C D E
FGRM
CapabilityParts 17 14 10 18 21per Day
To avoid the difficulty of constantly moving the constraint and changing culture, it is often better to elevate the whole chain rather than just the constraint. (McDonalds)
© Washington State University-2013 29
Simple Test
7 6
8 3 9
RM 1
RM 2 FG
Demand50
What is the constraint? Where are the buffers? The Rope?
© Washington State University-2013 30
Simple Diversion
20
40
5
RM
15 A
15 B
15 C
FG Demand
10
18
What is the constraint? Where are the buffers? The Rope?
© Washington State University-2013 31
Tough Complex
20
10
12
RM1
RM2
RM3
RM4
RM5
6 A $$
15 B$
FG Demand
1012
14
8
9 9
10
What is the constraint? Where are the buffers? The Rope?
© Washington State University-2013 32
Simple Complex
5RM
FG Demand
5
5
5
5
5
5
3
5
5
5
5
5
5
5
What is the constraint? Where are the buffers? The Rope?
© Washington State University-2013 33
Projects as Processes
• Projects Are: Unique Dependent on Precedence Activities Not Well Known Highly Variable Share Resources Concurrent with Other Projects Valued by Scope, Schedule and Cost
© Washington State University-2013 34
Project Problems
• Projects Are: Usually Late Have Too Many Changes Often Over Budget Lots of Rework Many Priority Battles Resources Not Available When Needed Jeopardize Scope for Cost or Schedule
© Washington State University-2013 35
Projects are Balancing Acts
Quality andScope
Timing andSchedule
BudgetedCosts
© Washington State University-2013 36
Then things Combine
Precedence Structure
Statistical Variation
HumanBehavior
Quality andScope
Timing andSchedule
BudgetedCosts
© Washington State University-2013 37
And Reality Sets In
Quality andScope
Timing andSchedule
BudgetedCosts
Precedence
Structure
Statistical Variation Human
Behavior
Bumpy Road of Reality
© Washington State University-2013 38
The Project Dilemma
• There is Always a Trade-Off
Meet Original Commitments
Meet Commitment
in Danger
Compensate for Early Mis-
Estimates
Not Jeopardize
Other Original Commitments
Not Compensate for Early Mis-
estimates
© Washington State University-2013 39
Resolving Project Problem Options
Meet Original Commitments
Meet Commitment in
Danger
Compensate for Early Mis-Estimates
Not Jeopardize Other Original Commitments
Not Compensate for Early Mis-
estimates
Add more time&money and decrease scope
Use our Safety Buffer Correctly
© Washington State University-2013 40
Consider the Aspects of Projects
Good Statistics
Central Limit Theorem(add enough things together and the total looks normal)
© Washington State University-2013 41
Typical Activity Duration
Mean
Standard Deviation
Normal Duration Time
Mean50% Probable
85% Probable
Project Task Duration Time
© Washington State University-2013 42
So, what is the Behavior?
•Engineering Pessimism:Estimate a safe value (85%)
Assigned Date
Time-->
•Parkinson's Law: “WorkExpands to full the time available” (Just keep tweaking! More is better!)
•Engineering Optimism:I’m good, I can beat 50%.
Level of Effort
•Student Syndrome: “Why start now? It isn’t due until Friday?” (There is more urgent work/party!) •Empirical evidence shows
most tasks complete on or after the due date
© Washington State University-2013 43
Engineering Perpetual Motion (overtime)
Assigned Date
Time-->
Level of Effort
NormalWork Load 1X
Actual Work Load 2X
© Washington State University-2013 44
The result is Bad Multi- Tasking
A1
A2A3
B1
B2B3
Ten Days Each Task
Project Manager A
Project Manager B
© Washington State University-2013 45
Politically Correct Schedule
A1 A2 A3
B1 B2 B3
10 20 30 40
30 Days Flow
50
© Washington State University-2013 46
More Like Actual Schedule
A1 A2 A3
B1 B2 B3
10 20 30 40
40 Days Flow
50
© Washington State University-2013 47
Elements of the Project Management Solution
• Prioritize
• Don’t Schedule Conflicts
• Avoid Bad Multi-Tasking
• Don’t Release Too Early/Too Late
• Buffer Critical Chain Buffers: Project / Feeding / Resources
• Schedule 50% Estimate Completion
• Communicate “Time Remaining”
• Negotiate Capability Not Dates
• No Milestones
© Washington State University-2013 48
TOC Flow Time
A1 A2 A3
B1 B2 B3
10 20 30 40
20 Days Flow
50
© Washington State University-2013 49
Don’t Schedule Conflict
Before
After TOC Leveling
© Washington State University-2013 50
Buffer the Project and NOT Individual Activities
Before with 85% Estimates
TOC Aggregated Buffer of Activities
Task Task Task Task Buffer
Task Buffer
Actual 50% Estimates with Individual Buffers
© Washington State University-2013 51
Protect the Critical Chain
Project Buffer
Feeding Buffer
© Washington State University-2013 52
Buffer Resources on the Critical Chain
Project Buffer
Feeding Buffer
Lt. Green be readyBuffer
Blue be ready
Green be ready
Cyan Resource be ready
© Washington State University-2013 53
Distribution System
• Retail Systems include time delay between demand cycles
• Production occurs to forecast
• Delivery Systems focus on efficiency--Transfer in large batches (long time between shipments)
• Errors in forecast are magnified ten fold
• Too much of the wrong inventory, too little of the right
© Washington State University-2013 54
Forecast Accuracy
Now ---> Future
Accuracy of Forecast
100%
Point where the world changes
Effective Response Zone
Death Response Zone
© Washington State University-2013 55
Pushing Inventory to the Retail Store
Manufacturing
Warehouse
DistributionStores
BEFORE
© Washington State University-2013 56
Locate Inventory Where it Provides Best Protection
After-Fast Production-Fast DeliveryAggregated Variability
Manufacturing
Warehouse
DistributionStores
© Washington State University-2013 57
Supply Chain Processes
• Supply Chain is made up of many independent links (Businesses or Business Units)
• Individual links do not provide a completed product
• There is significant interface problems Timing, Quality, Price, Value
• Links are in competition with each other / Leverage each other
© Washington State University-2013 58
Typical Supply Chain
Raw Materials
Refine /Prepare
Produce Transport
Distribute Retail Customer
© Washington State University-2013 59
Long and Short Duration Supply Chains
DairyCows
Creamery Deliver Retail Customer
Farmer Cannery Wholesale Retail Customer
© Washington State University-2013 60
Complex Combinations
Brakes
Tires
Bumpers
Upholstery
Engine
Transmission
Manuf.Car
Car Lot
Car Lot
Car Lot
© Washington State University-2013 61
Dedicated Chains
Mine SmelterRolling
MillProduct Steel
Sales
IndependentBusiness Unit
IndependentBusiness Unit
IndependentBusiness Unit
Single Firm - Totally Owned Industry - Sole Source
Transfer Prices Fixed by Policy
© Washington State University-2013 62
Competitive Chains
Oil Well
RefineryChemical
PlantClothMill
DressFactory
Customer
ClothMill
ClothMill
Oil Well
RefineryChemical
PlantDress
FactoryCustomer
Oil Well
RefineryChemical
PlantDress
FactoryCustomer
Transfer Prices at Market Prices
© Washington State University-2013 63
DBR Approach to Supply Chains
Raw Materials
ConstraintMachine Warehouse
Constraint Buffer Protects Replenishment
Shipping Buffer Protects Short Lead Demand
Low inventory system is very responsive to customer needs.
Low inventory system is product change.
© Washington State University-2013 64
In Non-Cooperative Worlds
Raw Material
ProduceConstraint
Transport Distribute Retail Customer
Constraint ClientSupply
Watch Diligently
Watch Diligently
Just-in-Time Production Using DBR
© Washington State University-2013 65
Reference Supply Chains
Snow River Dam Generator Powerlines
Electricity Customer
WaterWell
WaterTreatment
DistributionWater Tower
LocalLines
WaterCustomer
© Washington State University-2013 66
In A Cooperative World
Raw Material
ProduceConstraint
Transport Distribute Retail Customer
In the best world, individual business units cooperate and receive payment only when final customer pays.Inventory is greatly reduced. Quick delivery and response to change is possible.
Individual Links Must Share the Profits and Risks
© Washington State University-2013 67
Homework
• Read THE GOAL as fast as possible.
• Play the Dice Game as outlined in the Self- Study Session1a of this class. Report on your findings by email to [email protected]
• You will receive an email grading in response.
• The overall class Homework Status is linked at the top of the schedule and under the Angel <Lessons> Tab.
Keep Thinking! Dr Holt