VSM Workshop Teaches Lean Process Flow Design

Material Source: Lean Enterprise Institute
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Value Stream Mapping

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Learning to See
A Value Stream Mapping Workshop
Purpose:
1. Introduce value stream mapping in a hands-on
manner.
2. Develop your ability to “see the flow” and design
future state value streams.

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stamping welding assembly
• Helps you visualize more than the single process level
• Links the material and information flows
• Provides a common language
• Provides a blueprint for implementation
• More useful than quantitative tools
• Ties together lean concepts and techniques

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A) Follow a product’s production path from beginning to
end, and draw a visual representation of every process
in the material & information flows.
B) Then draw (using icons) a “future state” map of how
value should flow

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Waste
Things to Remember about Waste
• Waste is really a symptom rather than a root cause of the
problem
• Waste points to problems within the system (at both process
and value-stream levels)
• We need to find the address causes of waste
• The elements of production that add no value to the product
• Waste only adds cost and time

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Overproduction
= Making more than is required by the next process
= Making earlier than is required by the next process
= Making faster than is required by the next process

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Individual Efficiency vs. System Efficiency
How fast should we produce ?

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Understanding how the shop floor
currently operates. The foundation
for the future state.
Designing a lean flow.
Using the Value Stream Mapping Tool
product family
current state
drawing
future state
drawing
plan and
implementation

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Focus on one product family
Determine Product Families via:
Similar downstream “assembly” steps and equipment
Process Steps & Equipment
Spot
Weld
Robot
Weld
Flash
Remove
Paint
Manual
Assm.
Fixtures
Assm.
Electronic
Test
LH Steering
Bracket X X X X
RH Steering
Bracket X X X X
Instrument
Panel Brace X X X
Seat Rail X X
Bumper
Brackets X X X
PRODUCTS

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across companies
multiple plants
process level
single plant
(door to door)
begin here
Levels of a Value Stream

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Current State Drawing
Understanding how the shop floor
currently operates
 Material and Information flows
 Draw using icons
 Start with the “door to door” flow
 Have to walk the flow and get actuals
– No standard times
– Draw by hand, with pencil
 Foundation for the Future State
product family
current state
drawing
future state
drawing
plan and
implementation

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“ACME Stamping” Data Set
Acme Stamping Company produces several components for vehicle assembly plants.
This case concerns one product family: a steel instrument-panel bracket subassembly
in two types: one each for left-hand and right-hand drive versions of the same
automobile model. These components are sent to the State Street Vehicle Assembly
Plant (the customer).
CUSTOMER REQUIREMENTS :
• 18,400 pieces per month
12,000 per month of Type “LH”
6,400 per month of Type “RH”
• Customer plant operates on two shifts
• Palletized returnable tray packaging with 20 brackets in a tray and up to 10 trays
on a pallet. The customer orders in multiples of trays.
• One daily shipment to the assembly plant by truck
WORK TIME :
• 20 days in a month
• Two shift operation in all production departments
• Eight (8) hours every shift, with overtime if necessary
• Two 10-minute breaks during each shift
Manual processes stop during breaks
Unpaid lunch

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“ACME Stamping” Data Set (continued)
PRODUCTION PROCESSES :
• Acme’s process for this product family involves stamping a metal part followed by
welding and subsequent assembly. The components are then staged & shipped to
the vehicle assembly plant on a daily basis.
• Switching between Type “LH” (left-hand drive) and Type “RH” (right-hand drive)
brackets requires 1 hour changeover in stamping and 10-minute fixture change in
the welding processes.
• Steel coils are supplied by Michigan Steel Co.
Deliveries are made to Acme on Tuesdays and Thursdays.
ACME PRODUCTION CONTROL DEPARTMENT :
• Receives State Street’s 90/60/30-day forecasts and enters them to MRP
• Issues Acme 6-week forecast to Michigan Steel Co. via MRP
• Secures coil steel by weekly faxed order release to Michigan Steel Co.
• Receives daily firm order from State Street
• Generates MRP-based weekly departmental requirements based upon customer
order, WIP inventory levels, F/G inventory levels, and anticipated scrap and
downtime
• Issues weekly build schedules to Stamping, Welding, and Assembly processes
• Issues daily shipping schedule to Shipping Department

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“ACME Stamping” Data Set (continued)
PROCESS INFORMATION :
All processes occur in the following order and each piece goes through all processes.
1) STAMPING
(The press makes parts for many Acme products)
• Automated 200 Ton press with coil (automatic material feed)
• Cycle Time: 1 second (60 pieces per minute)
• Changeover time: 1 hour (good piece to good piece)
• Machine reliability: 85%
• Observed Inventory:
5 days of coils before stamping
4,600 pieces of Type “LH” finished stampings
2,400 pieces of Type “RH” finished stampings
2) SPOT-WELD WORKSTATION I
(dedicated to this product family)
• Manual process with one operator
• Cycle Time: 39 seconds
• Changeover time: 10 minutes (fixture change)
• Reliability: 100%
1,100 pieces of Type “LH”
600 pieces of Type “RH”
3) SPOT-WELD WORKSTATION II
• Changeover time: 10 minutes (fixture change)
4) ASSEMBLY WORKSTATION I
• Changeover time: none
• Observed inventory:
5) ASSEMBLY WORKSTATION II
• Changeover time: none
• Observed Finished-Goods Inventory in
Warehouse:
1,440 pieces of Type “RH”
6) SHIPPING DEPARTMENT
Removes parts from finished goods warehouse
and stages them for truck shipment to customer

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Develop the Current State Map

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Current State Map : Icons
MATERIAL FLOW ICONS
XYZ
Corporation
Outside Sources
ASSEMBLY
Manufacturing
Process
C/T = 45 sec.
C/O = 30 min
3 Shifts
2% Scrap
Data Box
300 pieces
1 Day
Inventory
Truck Shipment
Mon.
+ Wed.
PUSH
Arrow
Finished Goods
To Customer
First-In-First-Out
Sequence Flow
Max. 20 pieces
FIFO
Buffer or
Safety Stock
Operator
Manual
Information Flow
Electronic
Information Flow
Schedule
Weekly Schedule
Load Leveling
INFORMATION FLOW ICONS
GENERAL ICONS

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Future State Drawing
Designing a Lean Flow
• The power behind Value Stream Mapping is you
always need a future state !
• 70% & Keep Updating. Use pencil !
• Material & Information flows
• Basis for your Work Plan – like a “blueprint”
• Begin by drawing on Current State
• 1st iteration assumes existing steps & equipment
Can move equipment, combine, take out
conveyors, make minor purchases, etc.
product family
current state
drawing
future state
drawing
plan and
implementation
But there is a Problem!

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Notice that on this future-state map the four welding
and assembly process boxes have been combined into
one process box to indicate the continuous flow. A
small schematic sketch of a cell inside the process box
also indicates the cellular manufacturing idea.
First View of the Future-State Map
Showing Takt Time, Weld/Assembly
Cell, and the Finished-Goods
Supermarket
Building the Future State Map :
Stage

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Key Questions for the Future State
1. What is the takt time, based on the available working time of your downstream processes that
are closest to the customer?
2. Will you build to a finished goods supermarket from which the customer pulls, or directly to
shipping? (The answer to this question depends on several factors such as customer buying
patterns, the reliability of your processes, and the characteristics of your product. Building
directly to shipping will require either a reliable, short-lead-time, order-to-delivery lead time
involves only those processes from the pacemaker process downstream to delivery.)
3. Where can you use continuous flow processing?
4. Where will you need to use supermarket pull systems in order to control production of
upstream process?
5. At what single point in the production chain (the “pacemaker process”) will you schedule
production? (Remember that all material transfers downstream of the pacemaker process
need to occur as a flow.)
6. How will you level the production mix at the pacemaker process?
7. What increment of work will you consistently release and take away at the pacemaker
process?
8. What process improvements will be necessary for the value stream to flow as your future-
state design specifies? (This is the place to note any equipment and procedural improvements
that will be necessary, such as reducing changeover time or improving machine uptime. We
use the kaizen lightning burst icon to indicate these points in the process.)

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Produce to your Takt Time
Takt time synchronizes pace of production to match pace of sales.
Takt Time =
Available Work Time / Shift
Customer Demand Rate / Shift
Calculate Takt Time for ACME
Answer :
Available work time = 28,800 – 1200 = 27,600 seconds/shift
Customer demand = 640 units per shift
Takt Time = 60 seconds
Takt Time is like ‘Asking Rate’

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TAKT Time
Synchronizes pace of assembly to match pace of sales.
Rate for assembling a product based on sales rate.
Effective Working Time per Shift
Takt Time =
Customer Requirement per Shift
27,000 sec
= 59 sec
460 pieces

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Should Acme build steering brackets to a finished goods
supermarket or directly ship?
To move towards ‘Produce to Shipping’, ship from a supermarket
There are two varieties “RH” & “LH”
Since Customer requirement is in multiples of 20-bracket trays, this is the choice
for KANBAN size.
When we ship a tray of 20 brackets, a KANBAN to demand shipping to replenish
20 brackets from PRODUCTION is issued.
KANBAN
ASSEMBLY
LH
RH
Shipping
Customer
Customer
Requirement

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Where can ACME
introduce continuous flow?
BEFORE AFTER
Acme Stamping
current cycle times
Acme Stamping
weld/assembly cell cycle times
after process kaizen
Takt time
60
seconds
Takt time
60
seconds

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Problem Points in the Flow
Where One-Piece Flow Ends
How can we control production between flows ?
MRP-based schedules ?
Stamping Welding Assembly
customer

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Where will ACME need to use
supermarket pull system?
1. Difference in C/T of Stamping machine and other machines is high. Ideally we need a
‘smaller’ Stamping machine. Let us adopt a supermarket.
2. Stamping machine produces at the rate of 60 Stampings / hour. Let us adopt that as the
KANBAN quantity.
3. Design a supermarket between stamping and weld cum assembly station to withdraw 60
Stampings at a time.
4. Improve changeover time on Stamping machine so that quick changeover allows making LH
and RH pieces for one hour each and keep switching every hour.
5. Until we reduce the change over time, let us make a super market having 15 days of parts to
provide for replenishment delays and some quality & breakdown problems.

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What should be the frequency to receive coils
(raw material)?
1. Move to once a day supplies to reduce inventory by 80%.
2. Keep inventory only for 2 days.
Coils
Stamped
Parts
Weld/Assy
WIP
Finished
Good
Production
Lead Time
Total
Inventory
Turns
5 Days 7.6 Days 6.5 Days 4.5 Days 23.6 Days 10
2 Days 1.5 Days 4.5 Days 8 Days 30After
Before
Acme Stamping Lead Time Improvement

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What single point in the production chain
(the pacemaker process) should ACME Schedule?
Since all process steps downstream of the pacemaker process need to
occur in flow, in ACME, the scheduling point should be the welding /
assembly cell.

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Paced Withdrawal at the Pacemaker
• What amount of work do you schedule and take away at the
pacemaker?
• This amount = your management time frame.
(How often do you know your performance to customer demand?)
• Are you providing takt image ?
1 Week
1 Day
1 Shift
1 Hour
1 Pitch
1 Takt
?

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What process improvements will be necessary for Acme’s value
stream to flow as the future-state design describes?
Achieving the material and information flows we envision for Acme Stamping requires
the following process improvements:
 Reduction in changeover time and batch sizes at the stamping press, to allow
faster response to downstream usage. The goals are “ every part every day” and
then “ every part every shift”.
 Elimination of the time (10 minutes) required to change between left-drive and
right fixtures in welding, to make possible continuous flow and mixed production
from welding through assembly.
 Improvement in on-demand uptime of the second spot-weld machine, as it will
now be tied to other processes in a continuous flow.
 Elimination of waste in the weld/assembly cell, to reduce total work content down
to 168 seconds or less. (Which allows use of 3 operators at the current demand
level.
We mark these items on our future-state map with the kaizen lightening burst icon.

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AIM:
To bring cycle time at each work station lower than takt time.
How:
Identify KAIZENS’ that would help in this direction.
How Much:
1. Total time for welding and assembly work (39 + 46 + 62 + 40) = 187 seconds
2. Divide by takt time (60s) to get 3.12 operator requirement
3. Plan for Kaizens to reduce 4 work stations to 3 manned by 3 operators with
each station operating with cycle time less than takt time (60 seconds)
KAIZENS REQUIRED:
1. Total work < 168 seconds.
2. Weld changeover time reduction
3. Welder uptime increase.
KAIZEN
BURST

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Future State Map : Material and Information Flow

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Implementation
A Plan to Get There
• Don’t Wait !
• To “manage the exceptions” you need a plan!
1. Tie it to business objectives.
2. Break your future state into “loops”.
3. Make a VS Plan: What to do by when.
4. Now relate the FS Map to your layout.
5. VS Manager completes VS Review from in advance.
6. Conduct VS Reviews walking the flow.

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VSM Workshop Teaches Lean Process Flow Design

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