ng bb 18 theory of constraints
TRANSCRIPT
National GuardBlack Belt Training
Module 18
Theory of Constraints
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CPI Roadmap – Measure
Note: Activities and tools vary by project. Lists provided here are not necessarily all-inclusive.
TOOLS
•Process Mapping
•Process Cycle Efficiency/TOC
•Little’s Law
•Operational Definitions
•Data Collection Plan
•Statistical Sampling
•Measurement System Analysis
•TPM
•Generic Pull
•Setup Reduction
•Control Charts
•Histograms
•Constraint Identification
•Process Capability
ACTIVITIES• Map Current Process / Go & See
• Identify Key Input, Process, Output Metrics
• Develop Operational Definitions
• Develop Data Collection Plan
• Validate Measurement System
• Collect Baseline Data
• Identify Performance Gaps
• Estimate Financial/Operational Benefits
• Determine Process Stability/Capability
• Complete Measure Tollgate
1.Validate the
Problem
4. Determine Root
Cause
3. Set Improvement
Targets
5. Develop Counter-
Measures
6. See Counter-MeasuresThrough
2. IdentifyPerformance
Gaps
7. Confirm Results
& Process
8. StandardizeSuccessfulProcesses
Define Measure Analyze ControlImprove
8-STEP PROCESS
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Learning Objectives
Understand principles of TOC
Learn and apply the 5 focusing steps
Analyze Drum – Buffer - Rope
Differentiate and apply Little’s Law, takt
time and cycle time
Use TOC to improve a process
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Video: The Goal
Questions as you watch:
What are the 5 steps?
What is step 0?
Who/what is the bottleneck? Why?
How is the process fixed?
What is POOGI?
The Goal: A Process of Ongoing Improvement
Based on the book by Eliyahu Goldratt and Jeff Cox (2004)
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What is “Theory of Constraints” (TOC)?
Basic Principles of TOC:– A system must have a goal on which everything in that system is
evaluated
– Systems function as chains. Strengthening the weakest link benefits the system the most
– Optimum system performance is NOT equal to the sum of the individual process optima
– Systems operate in an environment of cause and effect. Visible problems are usually indicators (undesirable effects or UDE) of some critical root cause(s) that must be addressed
– An optimal solution deteriorates over time. Improvement must be continuous.
– Policy constraints are the most common and most difficult to break. Policy constraints offer the most opportunity for system improvement.
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TOC Measures of Progress
Throughput: The rate at which the system produces customer value or generates money
Inventory: Inventory is all the money invested in buying things that will at some time be sold (turned into Throughput) or that is tied up in the system (investment). Includes costs for raw materials, infrastructure, etc.
Operating Expense: The costs associated with turning Inventory into Throughput. Includes costs for labor, utilities, interest, etc.
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TOC Focuses on Constraints
A constraint is anything that impedes Throughput.
TOC concentrates on identifying and improving the worst impediment
Identifying constraints
– Visual identification of WIP (Work in Process)
– Calculating Throughput for each process step
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TOC Principles
What are the 5 focusing steps of Theory of Constraints?
1. Identify the constraint
2. Exploit the constraint
3. Subordinate everything else to the constraint
4. Elevate the constraint
5. Re-evaluate, go back to step 1
How can you identify the constraint?
Piles of WIP or calculate cycle time
Step 0: Know the Goal!
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D-B-R Concept
Drum –
Buffer –
Rope -
The speed at which the constraint
performs
A “safety stock” to account for
process variation so the constraint
doesn’t “starve”
A signal to make sure that correct
“number of things in process” put into
the system at the appropriate time
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TOC Definitions
Define Work in Process
WIP - (Work in Process) the “number of things in process” at any given time
Define Exit Rate
The amount of work completed over a
given period of time, which should also
equal customer demand (“completions per
hour”).
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TOC Definitions
What is Little’s Law and what does it represent?
Exit Rate
Work in Process (WIP)Process Cycle Time =
Voice of the process
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TOC Definitions
What is Takt Time and what does it represent?
Time available for work in the given time period
Customer demand for a given time period
Voice of the customer
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Common synonyms (often used
interchangeably):
– Flow Time
– Lead Time
– Throughput Time
TOC Definitions
Define Cycle Time
Cycle Time: The time it takes a product to
move (cycle) through a step or a process,
including queue and move times.
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TOC Example
What is the process cycle time?
P112 seconds
P210 seconds
P35 seconds
P48 seconds
12 + 10 + 5 + 8 = 35 seconds
If the Takt time is 11 seconds, where is the constraint, and why?
P1, it exceeds the Takt time
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Push: Work is pushed into the system or
process based on forecasts or schedules
Pull: A customer-driven system that produces
and moves a product/service only when the
customer needs it
TOC Flow & Pull
Explain the difference between Push and Pull work systems
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TOC is….(pick one)
A. A new way of getting people to work harder
B. Strengthening the weakest link (constraint) in a
system
C. A fancy scheduling tool meant to confuse workers
D. Adding extra inspections to get first time quality
Knowledge Check
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Lean is….(pick one)
A. A new weight loss program for employees
B. A war on Waste
C. Reducing manning
D. Adding extra inspections to get first time quality
Knowledge Check
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Six Sigma is….(pick one)
A. A new way of using metrics to blame workers
B. A war on variation
C. Complicated statistics meant to confuse workers
D. Adding extra inspections to get first time quality
Knowledge Check
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What other comments or questions
do you have?