Little's Law & Lean Flashcards
What is little’s law?
Throughput (Th)= Work In Process (WIP) x Cycle Time (CT)
What is throughout efficiency?
Throughput efficiency (%) = Work content x 100 Throughput time
refers to the work content needed to produce an item in a process expressed in terms of a percentage of total throughput time.
The lean philosophy of operations
Eliminate waste
Involve everyone
Continuous improvement
Lean as a set of techniques for managing operations
Basic working practices Design for manufacture Operations focus Small, simple machines Flow layout TPM Set-up reduction Total people involvement Visibility JIT supply
Lean as a method of planning and control
Pull scheduling
Kanban control
Levelled scheduling
Mixed modelling Synchronization
How does lean eliminate waste?
- Identify the causes and types of waste by understanding the customer perspective
- Eliminate waste through streamlined flow using e.g. Value stream mapping
- Eliminate waste through matching supply and demand e.g. Pull system
- Eliminate waste through minimizing variability e.g. Level delivery Schedule
- Eliminate waste through flexible processes
- Can be viewed through 5S
What are the basic lean principles
- 1 Piece Flow
- move away from batting, backlog and queues - Standard Work
- reduce variation & complexity - 5S
- sort; straighten; scrub; standardise; sustain - Pull systems
- create signals to pull products/ services. obvious when something is empty
What is visual management
ability to see the process
what is value stream mapping
understand how value is created and delivered
focuses on value-adding activities and distinguishes between value-adding and non-value-adding activities.
- Eliminate waste through reducing variability
Eliminate waste through streamlined flow
Criticisms of lean process improvement
- One size fits all solutions
- Too much standardization and people management = in inhumane working conditions
- Top down rather than bottom up problem solving
- Application of lean tools/techniques without understanding the philosophy and culture
define lean synchronisation
moving towards the elimination of all waste in order to develop an operation that is
- faster,
- more dependable,
- produces higher quality products and services
- operates at low cost’.
lean synchronisation is synonymous with…
continuous flow
manufacture high value-added manufacture
stockless production low-inventory production
fast-throughput manufacturing
lean manufacturing
Toyota production system
short cycle time manufacturing
What are the four elements of lean?
Waste elimination
Behaviour
Synchronisation
Customer focus
what is the ‘river and rocks’ analogy
- reducing the level of inventory (water) allows operations management (ship) to see problems in the process (rocks)
What is the traditional approach?
- focus on high capacity utilisation
- more production at each stage
- extra production goes into inventory because of continuing stoppages at stages
- high inventory means less chance of problems being exposed and solved
- more stoppages because of problems
What is the lean approach?
- focus on producing only when needed
- lower capacity utilisation, but
- no surplus production goes into inventory
- low inventory so problems are exposed and solved
- fewer stoppages
Causes of waste
Mura
- ‘lack of consistency’/ unevenness = periodic overloading of staff or equipment
Muri
- unreasonable= unnecessary/ unreasonable requirements put on a process will result in poor outcomes
Muda
- activities that are wasteful = do not add value to the operation or the customer.
what are waste activities?
consume time, resources and space, but do not contribute to satisfying customer needs
Seven types of waste
Over-production. Waiting time Transport Process. Inventory Motion Defects
What is over-production waste?
Make more than is required by the customer, or to make it earlier than required.
What is waiting time waste?
Any delay between when one process step/activity ends and the next step/activity begins
What is transport waste?
Movement of work between departments or offices that does not add to the value of the product or service
What is (over) processing waste?
Adding more value to a service or product than customers want or will pay for.
what is inventory waste?
More materials or information on hand than is currently required
What is motion waste?
Needless movement of people
While “transportation” refers to the movement of the work, “motion“ involves movement of workers
What is defects/ inspection waste
Any aspect of the product/service that does not conform to customer needs
example of waste in a hospital
Over-production
- requesting unnecessary tests from pathology
- keeping investigation slots ‘just in case’
Waiting
- Patients, theatre, staff results, prescriptions
and medicines
- doctors to discharge patients
Transport
– documents carried out to be signed by
various wards and managers
Over-processing
- duplication of information
- asking for patients’ details several times
Inventory
– excess stock in storerooms
- patients waiting to be discharged
- waiting lists
Rework
- readmission because of failed discharge
- repeating tests because correct information was not provided
Motion
- unnecessary staff movement looking
for paperwork
- not having basic equipment in every examination room
What are the 5’s?
Sort
-organise separate the needed from the rarely used
Straighten
- arrange and identify for ease of use
Shine
- clean and looks for ways to keep it clean
Standardize
- create rules to sustain the first 3 S’s
Sustain
- management audit to ensure adherence
n.b. continuous improvement
How to Sort (Seri)?
Eliminate all unnecessary items!!
Unnecessary refers to those things that are not needed for current work
Keep only things that are required in doing the job
How to Straighten (Seiton)?
Arrange items so that they can be found quickly by Anybody, Anywhere, Anytime.
Items should be easy to find, easy to use and easy to put away.
Tools
e.g. Colour Coding , Signboards, Labeling
Keep things in Order
How to Shine (Sieso) ?
Everything is clean, neat, tidy and ready to use
Tools:
e.g. Five Minute Shine
Cleaning & Inspection Checklists
Checklist of Activities Needing Maintenance
A clean work place enhances health and productivity
how to Standardize (Seiketsu)?
To prevent setbacks in the first 3 pillars (Sort, Set In Order and Shine)
Tools
eg. Best Practice documentation and sharing Checklists & job cycle charts
Learn a smarter way to Work
how to Sustain (Shitsuke)?
To make 5S a habit in the way we do our day-to-day activities
Tools include…..
e.g. 5 S contests
Visual management boards showing 5S audit
Slogans
Handbooks
Poka Yoke!
Make 5 S a habit
Criticisms of Lean Process Improvement
- One size fits all solutions
- Top down rather than bottom up problem solving
- Application of lean tools/ techniques without understanding the philosophy and culture
- Too much standardization and people management might result in inhumane working conditions
- Thus might be a paradox rather than panacea if not managed well
