Transcript
Karthik,Lean Manufacturing Engineer,Karthik.mirthipati@live.com
Session 2/8,Constraints, Bottlenecks & Leverage
Points
Topics
Understanding TOC Concepts.
Constraints & Types of Constraints
Identifying Bottlenecks
12 Leverage Points
Understanding TOC
Every system must have at least one constraint limiting output;
"Either you manage the constraints or they mange you”. “A system is strong as its weakest
link”
Understanding TOC
TOC drives manager to attack constraints in order to reach the company's primary goal i.e. make money.
TOC views System as Chain ( A chain of various operations)
Number of links together form a chain in similar manner a number of elements are responsible for systems formation.
TOC suggests remedy for dealing with the constraint.
Core of TOC
If you don’t impact the constraint, you have no effect.
Definitions
Constraint: a factor that limits a company's ability to achieve more of its goal.
Constraint
Anything that prevents the system from achieving more of its goal.
There is at least one and at most a few constraints in any given system.
The system is as strong as its constraint's.
Types of Constraints
Physical: e.g. equipment, material, man-power, space
Policy: e.g. rules & regulations, “how things are done”
Paradigm: e.g. “we must keep the machine running to lower cost ”
Market: e.g. production capacity > sales.
Constraints
A system Optimal performance is NOT THE sum of local optima.
A system has only one constraint at a time.
Constraints can never be eliminated.
The can move from one part of the system to another.
TOC Works better when the constraints are clearly definable.
If does not work so well when capacity is balanced across the plant.
Bottleneck
Bottleneck : Any resource with a capacity equal to or less than the demand placed upon it.
"An hour lost at a bottleneck is an hour lost for the total system. An hour saved at a non-bottleneck is just a mirage."
“Every system has a bottleneck”
Types of Bottlenecks
Short Term : They are caused by temporary problems.
Long Term: These occur all the time.
Significance of Bottlenecks
Maximum speed of the process is the speed of the slowest operation.
Any improvements will be wasted unless the bottleneck is relieved.
Bottlenecks must be identified and improved if the process is to be improved.
How to Identify Bottlenecks
Accumulation: The production line process that accumulates the longest queue is usually a bottleneck.
Throughput: The throughput of a production line is directly linked to the output of the bottleneck machine.
Full Capacity: The machine that uses the highest percentage of its capacity is the bottleneck.
Wait Times: When there is a bottleneck, the machine after the bottleneck has high wait times, because the bottleneck is holding up production.
CCR: Capacity Constrained Resource
A Resource that is not a constraint but will become a constraint unless scheduled carefully.
A bottleneck is a constraint although it may be the result of scheduling convention.
“Give me a lever long enough … and I shall move the world”
– Archimedes
12 Leverage Points – Part 1
12. Constants, parameters, numbers (such as subsidies, taxes, standards).
11. The sizes of buffers and other stabilizing stocks, relative to their flows.
10. The structure of material stocks and flows (such as transport networks, population age structures).
9. The lengths of delays, relative to the rate of system change.
12 Leverage Points Part 2
8. The strength of negative feedback loops, relative to the impacts they are trying to correct against.
7. The gain around driving positive feedback loops.
6. The structure of information flows (who does and does not have access to information).
5. The rules of the system (such as incentives, punishments, constraints).
12 Leverage Points Part 3
4. The power to add, change, evolve, or self-organize system structure.
3. The goals of the system.
2. The mindset or paradigm out of which the system — its goals, structure, rules, delays, parameters — arises.
1. The power to transcend paradigms.
Summary
Understanding TOC Concepts.
Constraints & Types of Constraints
Identifying Bottlenecks
12 Leverage Points
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