Basic Elements of Lean

Unit 1Unit 1
1.3 Basic Elements of Lean1.3 Basic Elements of Lean
ManufacturingManufacturing
Unit I-Introduction to Lean Manufacturing

Lecture OutlineLecture Outline
 Basic Elements of Lean Production
 Benefits of Lean Production
 Implementing Lean Production
 Lean Services

Lean Production
 Doing more with less inventory, fewer
workers, less space
 Just-in-time (JIT)
 smoothing the flow of material to arrive
just as it is needed
 “JIT” and “Lean Production” are used
interchangeably
 Muda
 waste, anything other than that which
adds value to the product or service

Waste in OperationsWaste in Operations

Waste in Operations (cont.)Waste in Operations (cont.)

Basic ElementsBasic Elements
1. Flexible resources
2. Cellular layouts
3. Pull production system
4. Kanban production control
5. Small lot production
6. Quick setups
7. Uniform production levels
8. Quality at the source
9. Total productive
maintenance
10. Supplier networks

Flexible Resources
 Multifunctional workers
 perform more than one job
 general-purpose machines perform
several basic functions
 Cycle time
 time required for the worker to complete
one pass through the operations
assigned
 Takt time
 The pace at which production should take
place to match customer demand

Standard Operating
Routine for a Worker

Cellular Layouts
 Manufacturing cells
 comprised of dissimilar machines brought
together to manufacture a family of parts
 Cycle time is adjusted to match takt time
by changing worker paths

Worker Routes Lengthen as
Volume Decreases

Pull System
 Material is pulled through the system whenMaterial is pulled through the system when
neededneeded
 Reversal of traditional push system whereReversal of traditional push system where
material is pushed according to a schedulematerial is pushed according to a schedule
 Forces cooperationForces cooperation
 Prevent over and underproductionPrevent over and underproduction
 While push systems rely on a predetermined
schedule, pull systems rely on customer
requests

Copyright 2006 John Wiley & Sons, Inc.Copyright 2006 John Wiley & Sons, Inc. 15-15-1414
KanbansKanbans
 Card which indicates standard quantityCard which indicates standard quantity
of productionof production
 Derived from two-bin inventory systemDerived from two-bin inventory system
 Maintain discipline of pull productionMaintain discipline of pull production
 Authorize production and movement ofAuthorize production and movement of
goodsgoods

Origin of KanbanOrigin of Kanban
a) Two-bin inventory systema) Two-bin inventory system b) Kanban inventory systemb) Kanban inventory system
ReorderReorder
cardcard
Bin 1Bin 1
Bin 2Bin 2
Q - R
KanbanKanban
RR
QQ = order quantity= order quantity
RR = reorder point - demand during lead time= reorder point - demand during lead time

Types of KanbanTypes of Kanban
 Production kanban
 authorizes production of
goods
 Withdrawal kanban
 authorizes movement of
goods
 Kanban square
 a marked area designated
to hold items
 Signal kanban
 a triangular kanban
used to signal
production at the
previous workstation
 Material kanban
 used to order material in
advance of a process
 Supplier kanban
 rotates between the
factory and suppliers

Determining Number ofDetermining Number of
KanbansKanbans
wherewhere
NN = number of kanbans or containers= number of kanbans or containers
dd = average demand over some time period= average demand over some time period
LL = lead time to replenish an order= lead time to replenish an order
SS = safety stock= safety stock
CC = container size= container size
No. of Kanbans =No. of Kanbans =
average demand during lead time + safety stockaverage demand during lead time + safety stock
container sizecontainer size
NN ==
dLdL ++ SS
CC

Determining Number ofDetermining Number of
Kanbans: ExampleKanbans: Example
dd = 150 bottles per hour= 150 bottles per hour
LL = 30 minutes = 0.5 hours= 30 minutes = 0.5 hours
SS = 0.10(150 x 0.5) = 7.5= 0.10(150 x 0.5) = 7.5
CC = 25 bottles= 25 bottles
Round up to 4 (to allow some slack) orRound up to 4 (to allow some slack) or
down to 3 (to force improvement)down to 3 (to force improvement)
NN = == =
= = 3.3 kanbans or containers= = 3.3 kanbans or containers
dLdL ++ SS
CC
(150 x 0.5) + 7.5(150 x 0.5) + 7.5
2525
75 + 7.575 + 7.5
2525

Small LotsSmall Lots
 Require less space and capitalRequire less space and capital
investmentinvestment
 Move processes closer togetherMove processes closer together
 Make quality problems easier toMake quality problems easier to
detectdetect
 Lower inventory levelsLower inventory levels
 Make processes more dependent onMake processes more dependent on
each othereach other

Inventory Hides ProblemsInventory Hides Problems

Less Inventory Exposes ProblemsLess Inventory Exposes Problems

Components of Lead TimeComponents of Lead Time
 Processing timeProcessing time
 Reduce number of items or improve efficiencyReduce number of items or improve efficiency
 Move timeMove time

Reduce distances, simplify movements, standardizeReduce distances, simplify movements, standardize
routingsroutings
 Waiting timeWaiting time
 Better scheduling, sufficient capacityBetter scheduling, sufficient capacity
 Setup timeSetup time
 Generally the biggest bottleneckGenerally the biggest bottleneck

Quick SetupsQuick Setups
 Internal setupInternal setup
 Can be performedCan be performed
only when aonly when a
process is stoppedprocess is stopped
 External setupExternal setup
 Can be performedCan be performed
in advancein advance
 SMED PrinciplesSMED Principles

Separate internal setup fromSeparate internal setup from
external setupexternal setup

Convert internal setup to externalConvert internal setup to external
setupsetup

Streamline all aspects of setupStreamline all aspects of setup

Perform setup activities inPerform setup activities in
parallel or eliminate them entirelyparallel or eliminate them entirely

Common Techniques for ReducingCommon Techniques for Reducing
Setup TimeSetup Time

Common Techniques for ReducingCommon Techniques for Reducing
Setup Time (cont.)Setup Time (cont.)

Uniform Production Levels
 Result from smoothing production
requirements
 Kanban systems can handle +/- 10%Kanban systems can handle +/- 10%
demand changesdemand changes
 Smooth demand across planningSmooth demand across planning
horizonhorizon
 Mixed-model assembly steadiesMixed-model assembly steadies
component productioncomponent production

Mixed-Model SequencingMixed-Model Sequencing

Quality at the Source
 Visual control
 makes problems visible
 Poka-yokes
 prevent defects from
occurring
 Kaizen
 a system of continuous
improvement; “change for
the good of all”
 Jidoka
 authority to stop the
production line
 Andons
 call lights that signal
quality problems
 Under-capacity
scheduling
 leaves time for planning,
problem solving, and
maintenance

Examples of VisualExamples of Visual
ControlControl

Examples of VisualExamples of Visual
Control (cont.)Control (cont.)

Total ProductiveTotal Productive
Maintenance (TPM)Maintenance (TPM)
 Breakdown maintenanceBreakdown maintenance
 Repairs to make failed machine operationalRepairs to make failed machine operational
 Preventive maintenancePreventive maintenance
 System of periodic inspection andSystem of periodic inspection and
maintenance to keep machines operatingmaintenance to keep machines operating
 TPM combines preventive maintenanceTPM combines preventive maintenance
and total quality conceptsand total quality concepts

TPM RequirementsTPM Requirements
 Design products that can be easily producedDesign products that can be easily produced
on existing machineson existing machines
 Design machines for easier operation,Design machines for easier operation,
changeover, maintenancechangeover, maintenance
 Train and retrain workers to operate machinesTrain and retrain workers to operate machines
 Purchase machines that maximize productivePurchase machines that maximize productive
potentialpotential
 Design preventive maintenance plan spanningDesign preventive maintenance plan spanning
life of machinelife of machine

Unneeded equipment, tools, furniture;
unneeded items on walls, bulletins; items
blocking aisles or stacked in corners;
unneeded inventory, supplies, parts; safety
hazards
Items not in their correct places; correct
places not obvious; aisles, workstations, &
equipment locations not indicated; items not
put away immediately after use
Floors, walls, stairs, equipment, & surfaces
not lines, clean; cleaning materials not easily
accessible; labels, signs broken or unclean;
other cleaning problems
Necessary information not visible; standards
not known; checklists missing; quantities and
limits not easily recognizable; items can’t be
located within 30 seconds
Number of workers without 5S training;
number of daily 5S inspections not performed;
number of personal items not stored; number
of times job aids not available or up-to-date
Keep only what you
need
A place for
everything and
everything in its
place
Cleaning, and
looking for ways to
keep clean and
organized
Maintaining and
monitoring the first
three categories
Sticking to the rules
 Seiri
(sort)
 Seiton
(set in order)
 Seisou
(shine)
 Seiketsu
(standardize)
 Shisuke
(sustain)
5S Scan Goal Eliminate or Correct

Supplier Networks
 Long-term supplier contracts
 Synchronized production
 Supplier certification
 Mixed loads and frequent deliveries
 Precise delivery schedules
 Standardized, sequenced delivery
 Locating in close proximity to the customer

Benefits of Lean
Production
 Reduced inventory
 Improved quality
 Lower costs
 Reduced space requirements
 Shorter lead time
 Increased productivity

Benefits of Lean
Production (cont.)
 Greater flexibility
 Better relations with suppliers
 Simplified scheduling and control activities
 Increased capacity
 Better use of human resources
 More product variety

Implementing Lean Production
 Use lean production to finely tune anUse lean production to finely tune an
operating systemoperating system
 Somewhat different in USA than JapanSomewhat different in USA than Japan
 Lean production is still evolvingLean production is still evolving
 Lean production isn’t for everyoneLean production isn’t for everyone

Lean ServicesLean Services
 Basic elements of leanBasic elements of lean
production apply equally toproduction apply equally to
servicesservices
 Most prevalent applications
 lean retailing
 lean banking
 lean health care

Basic Elements of Lean

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