Thanks to various sponsors for their support. The document then discusses key concepts of Lean, including:
- Focusing on flow efficiency over resource efficiency in order to minimize waste and secondary needs.
- Little's Law, the Law of Bottlenecks, and the Law of Variation, which demonstrate that reducing variation and bottlenecks improves flow.
- An example of mailing envelopes illustrates how single-piece flow is more efficient than large batches or small batches by eliminating waste between processes.
Reassessing the Bedrock of Clinical Function Models: An Examination of Large ...
What is Lean?
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3. What is Lean?
Dave Adsit
Architect @ Pluralsight
@davidadsit
dave@pluralsight.com
codeobsession.blogspot.com
4. Efficiency
the ability to do something or produce something without
wasting materials, time, or energy
5. Resource Efficiency
Focus on the value adding resource in the organization
Keep people busy
Key Metric: How much is a resource utilized in a period of time?
6. Flow Efficiency
Focus on the unit processed by the organization
Keep adding value to the flow unit
Key Metric: How much is a flow unit processed during time period?
10. Why can’t we just have both?
● Little’s Law
● Law of Bottlenecks
● Law of the Effects of Variation
11. Little’s Law
average queue size = arrival rate x cycle time
Queue Formation
Pros
Level out workload
Maximize resource utilization
Cons
Increase throughput time
Decreases flow efficiency
12. Why is Cycle Time so confusing?
Lead Time
How much time one has to wait to get a thing
This is the time the customer sees and cares about
Takt Time
The average time between successive deliveries
Hours in operation / Units completed
Order Lead Time
The clock starts when the customer makes the request and ends once
delivered
Production Lead Time
The clock starts when work begins on the request and ends when the item is
delivered
http://itsadeliverything.com/lead-time-versus-cycle-time-untangling-the-confusion
13. Law of Bottlenecks
● There is always a bottleneck
● Immediately prior to a bottleneck, there is always a queue
● Throughput time in a process is primarily affected by the
stage of the process that has the longest cycle time
● Stages after the bottleneck must wait for a flow unit to add
value to, so are not fully utilized
14. Law of the Effects of Variation
Cycle time increases with utilization;
variability exacerbates the effect.
Kingman's approximation
τ is the mean service time
λ is the mean arrival rate
ρ = λ/μ is the utilization
ca is the coefficient of variation for arrivals
cs is the coefficient of variation for service times
15. Variation is Unavoidable
● Common cause variation
○ Manpower
○ Mother nature
○ Materials
○ Method
○ Measurements
○ Machine
● Special cause variation
○ Luck
○ Black swan events
17. The Efficiency Paradox
Focus on utilizing resources efficiently
tends to increase the amount of work
there is to do without adding value.
18. Secondary Needs
● Secondary needs arise as a
consequence of the failure to
meet the primary need of a
customer
● Secondary needs often cause
other secondary needs
● Superfluous work is a very
sophisticated form of waste,
since we often fail to realize
that it is waste at all.
19. Improving Flow
● Work faster
● Add more capacity to the system
● Reduce variation in flow units
● Reduce the flow units in process
20. Resolving the Efficiency Paradox
By focusing on flow efficiency, an organization can eliminate
many of the secondary needs that arise as a consequence of
low flow efficiency.
More specifically, any decision that decreases throughput time,
the amount of flow units in process, and/ or the amount of
restarts will eliminate superfluous work.
Paradoxically, not focusing on utilizing resources makes it
possible to deliver value more effectively.
- This is Lean
23. First Delivery
Large Batch
1. Write "Code Camp 2016" on all 10
papers
2. Pass batch to next station
3. Fold all 10 papers
4. Pass batch to next station
5. Stuff all 10 envelopes
6. Pass batch to next station
7. Seal all 10 envelopes
8. Pass batch to next station
9. Write "Utah Geek Events" on the
outside of all 10 envelopes
10.All stations stand up! You’re done!
Single Piece Flow
Repeat 10 times:
{
1. Write "Code Camp 2016" on 1 piece
of paper
2. Pass the paper to the next station
3. Fold the paper
4. Pass the paper to the next station
5. Stuff it in the envelope
6. Pass the envelope to the next station
7. Seal the envelope
8. Pass the envelope to the next station
9. Write "Utah Geek Events" on the
outside of the envelope
}
10.All stations stand up! You’re done!
24. First Delivery
Small Batch
Repeat 2 times:
{
1. Write "Code Camp 2016" on 5 pieces
of paper
2. Pass the papers to the next station
3. Fold all 5 papers
4. Pass the papers to the next station
5. Stuff 5 envelopes
6. Pass envelopes to the next station
7. Seal 5 envelopes
8. Pass envelopes to the next station
9. Write "Utah Geek Events" on the
outside of the envelopes
}
10.All stations stand up! You’re done!
WIP Limit of 1 per Station
1. Write "Code Camp 2016" on 1 piece of
paper
2. Hold the paper until the folder takes it
3. Take the paper and fold it
4. Hold the paper until the stuffer takes it
5. Take the paper and stuff it in the
envelope
6. Hold the envelope until the sealer takes
it
7. Take the envelope and seal it
8. Hold the envelope until the addresser
takes it
9. Take the envelope and write "Utah
Geek Events" on the outside of the
envelope
10.Repeat until all 10 are complete then
stand up!
25. First Delivery
WIP Limit of 1 per Station
1. Write "Code Camp 2016" on 1 piece of
paper
2. Hold the paper until the folder takes it
3. Take the paper and fold it
4. Hold the paper until the stuffer takes it
5. Take the paper and stuff it in the
envelope
6. Hold the envelope until the sealer takes
it
7. Take the envelope and seal it
8. Hold the envelope until the addresser
takes it
9. Take the envelope and write "Utah
Geek Events" on the outside of the
envelope
10.Repeat until all 10 are complete then
stand up!
Queues Between Stations
1. Write "Code Camp 2016" on 1 piece
of paper
2. Stack the paper for the next station
3. Fold the paper
4. Stack the paper for the next station
5. Stuff the envelope
6. Stack the envelope for the next
station
7. Seal the envelope
8. Stack the envelope for the next
station
9. Write "Utah Geek Events" on the
outside of the envelopes
10.Stand up when you complete your
station