Value Stream Mapping

Technological University of Tecamachalco

Lean Manufacturing

Value Stream Mapping

A means of understanding where you are adding value and how to do so more effectively.

A paper and pencil tool to help you visualize and understand the flow of material and information as a product or customer makes its way through your system.To learn more see: Learning to See by Rother and Shook, The Lean

Enterprise Institute, 2003.

Why Value Stream Mapping?

Visualize the whole process See the sources of waste Provides a common language for

improvement Makes decisions about flow apparent Ties together lean techniques Forms the basis of an improvement plan Shows linkage between information and

material flows

How to begin…

Start with a single product family. Customers only care about their specific

product. Having all product flows on a single map is too

complicated. Be specific – how many finished part numbers

in family, how much is demanded, and how often.

Selecting a Product Family

If mix is complicated you can crease a matrix:

Assembly Steps and Equipment

P

R

O

D

U

C

T

S

1 2 3 4 5 6 7 8

A X X X X X

B X X X X X X

C X X X X X X

D X X X X X

E X X X X X

F X X X X X

G X X X X X

Select a Value Stream Manager

Nobody is usually responsible for the entire value stream.

Crossing organizational boundaries Need someone who reports to top manager

at your site for power necessary for change

Don’t…

Split the task up among area managers and hope to put it all together at the end.

Map your organization, map the flow of products or customers.

Start too big or too small, begin at the door to door level.

Ignore the flow of information

Draw the Current State Map

Always collect information while walking the actual process.

Begin with a quick door-to-door walk. Begin with shipping and work upstream. Bring your stopwatch and do not rely on

information that you do not personally obtain. Map the whole value stream yourself Always draw by hand and in pencil (no

computers)

Value Stream Mapping Symbols

VSM Exercise – Acme Stamping

The Product We make instrument panel brackets out of stamped steel, for

the automobile industry. The brackets come in right-hand (RH) and left-hand (LH)

versions depending on which side the steering wheel is mounted on.

We make other stamped components in our facility, but this project is focused on the instrument panel brackets.

Adapted from Learning to See: Value Stream Mapping to Add Value and Eliminate MUDA , Rother and Shook, Lean Enterprise Institute 1999

Acme (2)

Customer (State Street Assembly Plant) We ship daily to the assembly plant by truck. Product is shipped on pallets of 10 trays, with 20 brackets in

each tray. The customer runs two shifts a day. Demand for the brackets is 18,400 per month

12,000 LH 6,400 RH

Primary Supplier (Michigan Steel) Deliveries of Steel Coil arrive on Tuesdays and Thursdays.

Acme (3)

Our Plant Operates two 8-hour shifts, 20 days a month.

There are two paid 10 minute breaks each shift. All manual processes stop during the breaks.

Acme (4)

Step 1 – Stamping Rough brackets are stamped out of steel coil on a 200 ton press at

a rate of 60 per minute. The press is automated and will run by itself once set up.

Setup requires 1 hour and the machine is 85% reliable. Observed inventory:

5 days of steel coil 4,600 LH rough brackets 2,400 RH rough brackets

The press makes parts for many other Acme products.

Acme (5)

Step 2 – Spot Welding Workstation 1 Several strengthening welds are made in a manual process

with one operator. This process takes 39 seconds per bracket, and is

considered 100% reliable. This workstation is dedicated to instrument panel brackets,

but it takes 10 minutes of fixture changes to move from LH to RH bracket production.

Observed inventory: 1,100 LH partially welded brackets 600 RH partially welded brackets

Acme (6)

Step 3 – Spot Welding Workstation 2 Several threaded connectors are welded onto the part in a

manual process with one operator. This process takes 46 seconds per bracket, and is

considered 100% reliable. This workstation is also dedicated to instrument panel

brackets, but take 10 minutes of fixture changes to move from LH to RH bracket production.

Observed Inventory: 1,600 LH fully welded brackets 850 RH fully welded brackets

Acme (7)

Step 4 – Assembly Workstation 1 Several connectors and fasteners are added during a manual

process with one operator. This process takes 62 seconds per bracket, and is considered

100% reliable. This workstation is dedicated to instrument panel brackets, and can

move immediately between LH and RH bracket production. Observed inventory:

1,200 LH partially assembled brackets 640 RH partially assembled brackets

Acme (8)

Step 5 – Assembly Workstation 2 The final connectors and fasteners are added during a manual

process with one operator. This process takes 40 seconds per bracket, and is considered

100% reliable. This workstation is also dedicated to instrument panel brackets,

and can move immediately between LH and RH bracket production. Observed inventory:

2,700 LH finished brackets in warehouse 1,440 RH finished brackets in warehouse

Acme (9)

Shipping Department: Pulls parts from the warehouse and stages them for the daily

truck. Production Control Department (MRP-based)

Receives: 90/60/30 day forecasts, and a daily firm order from State Street

Assembly Plant.

Issues: 6 week forecast to Michigan Steel Weekly order by fax to Michigan Steel Weekly MRP-based schedule to stamping, welding and assembly

departments. Issue daily shipping schedule to shipping department.

Guidelines for the Lean Value Stream

Produce to your takt time Develop continuous flow wherever possible Use Supermarkets to control production where

continuous flow does not extend upstream Try to send the customer schedule to only one

production process Level the production mix Level the production volume Develop the ability to make every part every day (or

faster) upstream of the pacemaker process.