6- Lean Flashcards
Where did lean orginate?
Japanese auto companies, especially Toyota
What external factors drove Lean operations? x3
Small domestic markets => need to export
Highly regulated economy => difficulties in supplies
Strict labour laws => no cheap immigrant workforce
Difference between Lean and Taylorism?
Taylorism: high division of labour
Lean: highly skilled labour
Toyta Production System Lean Characteristics? [8]
Elimination of waste (value-creating activities)
Just in Time Synchronisation
Levelling
Pull Control
Continuous improvement
Automation
Teamwork
Visualisation
To manage value, Lean uses 3 principles:
Eliminate waste
Involve everyone
Improve continuously
7 Types of waste
Inventory Overproduction Waiting Unnecessary transportations Processing waste Inefficient work methods Product defects
Whats the difference between Internal and External Activities?
Internal activities
can only be done when machine not running
-> directly affect changeover time
External activities
can be done when machine is running
-> do not affect changeover time
What are the characteristics of lean Cell Layouts? 4
Functional layouts do not pre-select transforming resources - create WIP, delays, unnecessary movement
Cells group all transforming resources (machines and tools) necessary to process similar types of transformed resources that are pre-selected
Compactness => cell layouts make WIP almost impossible to form
Benefits of cell layouts: reduced changeover times, high utilisation, ease of cross-training operators
5 Benefits and 5 Drawbacks of Small-scale process technology in cell layouts:
Benefits: Cheap tooling, but may reduce utilisation Easy to move and re-configure Quick to set-up Flexible scheduling Easy maintenance
Drawbacks: Expensive tooling, economies of scale Hard to move Slow to set-up Inflexible scheduling Expensive maintenance
What is Line Balancing?
To reduce waste due to idle time, workload must be balanced evenly across the workstations
Traditional mass production involves a lot of ‘___ workers’ who do not directly contribute to value
Traditional mass production also gives little ___ to workers because ____ of labour assigns autonomy to managers
Well-trained, motivated workers are the heart of Lean; they are given more ____but also expected to do more
Workers can be ___-trained to perform several parts of a process and operate variety of machines, adding to ____ and helping ___ ___
Traditional mass production involves a lot of ‘indirect workers’ who do not directly contribute to value
Traditional mass production also gives little autonomy to workers because division of labour assigns autonomy to managers
Well-trained, motivated workers are the heart of Lean; they are given more autonomy but also expected to do more
Workers can be cross-trained to perform several parts of a process and operate variety of machines, adding to flexibility and helping line balancing
Continuous Improvement:
Lean workers have responsibility for ___ and must take part in continuous ____
P___ ___ skills are trained
T___ ____ systems (andon) can be used to signal problems at workstations
Amazon.com: service agents are able to ___ products out from the website if they suspect that the product has repetitive ____
Lean workers have responsibility for quality and must take part into continuous improvement
Problem solving skills are trained
Traffic light systems (andon) can be used to signal problems at workstations
Amazon.com: service agents are able to pull products out from the website if they suspect that the product has repetitive faults
What is the formula for Work In Progress?
What are the consequences of not controlling WIP?
What do the other to variable in the WIP formula mean?
WIP = throughput time × arrival rate
If we do not control this, fluctuations in throughput time will occur, disrupting the smoothness of output flow
Arrival rate: rate at which jobs are assigned to the system
Throughput time: is the time that it takes for a product to be manufactured.
Advantages of Reduce inventories
Permit greater flexibility in scheduling
Quicker response to changing demand
Can be used with EOQ model
What is a push system?
Which way does information move?
What may happen if next work station is not ready to commence?
What systems are normally used to control?
Push system: output is pushed into the next work station once it is completed
Information moves forwards in the system
Work may pile up into WIP inventories if the next work station is not ready to commence
Implemented by automated MRP / ERP systems that seek system-wide efficiency
What is a Pull/Just in time system?
Which way does information move?
How does work move?
What systems are normally used to control?
Pull system: output is pulled from the preceding station once it is needed for the next stage
Information moves backwards through the system
Work moves just in time for the next operation
Implemented by manual Kanban systems
[Kanban cards provide the authorisation to move parts]
Close supplier relationships:
Traditional systems allow to use __ __ for quality inspections and returns
__ __ ___ systems do not allow ___, therefore poor quality disrupts the smooth flow of goods
Inspections do not __ __ and are Muda
Close supplier relationships in ___ systems allow achieving high ___ levels
Moreover, __ __ __ systems emphasise close supplier relationships to allow small ___ sizes
Traditional systems allow to use slack time for quality inspections and returns
JIT systems do not allow slack, therefore poor quality disrupts the smooth flow of goods
Inspections do not add value and are Muda
Close supplier relationships in Lean systems allow achieving high quality levels
Moreover, JIT systems emphasise close supplier relationships to allow small lot sizes
Define MURA, MURI and MUDA?
Key concepts in lean process thinking, like the Toyota Production System (TPS) as one of the three types of deviation from optimal allocation of resources
MURA = Un-evenness
MURI = Over-burden
MUDA = Waste
Explain Preventive maintenance using 5S?
To lessen the probability of workplace incidence/failure
[2 of them basically the same]
[in fact most of them are, it’s basically a joke]
Sort (Seiri) – Eliminate what is not needed and keep what is needed
Straighten (Seiton) – Position things in such a way that they can be easily reached whenever they are needed
Shine (Seiso) – Keep things clean and tidy; no rubbish or dirt in the work area
Standardize (Seiketsu) – Maintain cleanliness and order – perpetual neatness
Sustain (Shitsuke) – Develop a commitment and pride in keeping to standards
x4 Ways to implement Lean? The 4….
Philosophy – spread culture first, techniques follow
Process – value-focused and value-stream driven
People – implement through staff and patient buy-in of Lean
Problem solving – implement through innovation events and workshops
x10 Reasons why Implementation of lean fails?
Anagram
Poor strategic integration
Conflicting measures (McMahon, 2013)
Relying on a champion
No leadership involvement
Lack of employee understanding
Employees not engaged
All education – no implementation
Forgetting the customer
Copying others
Lean as a project
Scheduling in Large Batches:
What is Non-levelled and Levelled Scheduling?
What are the disadvantages of Non-levelled?
Levelled Scheduling is a Manufacturing technique that aims to create a smooth flow of production over a period. Its objective is to minimize disruptions caused by sudden changes in demand levels by matching the product family schedules with product-by-product schedules. Both the sales and production departments must agree on a fixed level of output volume and output duration.
Non-levelled creates a build up of inventory that has not adding value, just sitting idle as spare capacity.
Small Production Lots:
What does it describe?
describes the manufacture of a small number of items of the same type and design.
Leads to smaller average inventories over time as more replenishments made - greater flexiblity
