1. business and industrial
2. manufacturing

THE QUICK-START APPROACH TO JOBSHOPLEAN: HOW TO
INITIATE THE IMPLEMENTATION OF LEAN IN A HIGH-MIX,
LOW-VOLUME MANUFACTURING FACILITY
Bryan Wang
The Ohio State University
Abstract
Lean manufacturing has been recognized as one of
the best practices in varieties of industries.
However, some lean practices are suited for
assembly-like organizations, not for high-mix,
low-volume jobshops. This case study presents
how a custom forge shop uses a strategyQuick-Start Approach to Jobshoplean- to analyze
the current state, to create a lean culture, to train
the managers and employees, and to reduce cost
and improve productivity.
Figure 1.
Background
This case study is based on a 12 week long lean
manufacturing project at a custom forge shopBula Forge & Machine Inc. in Cleveland, Ohio.
Bula offers customers a fully-integrated forging
and machining facility with many value-added
services including assembly, sub-assembly,
fabrication, heat treatment, machining, welding,
protective finishes and more. Bula specializes in
production runs of 50 pieces to 10’s of thousands,
working with carbon, alloy, and stainless steels in
weights of 1 to 60 pounds. The project was
supported by Department of Defense (DOD) and
Department of Logistic Agency (DLA) with the
objectives to reduce the production lead times of
forgings supplied to DLA and DOD, to modify the
Toyota Production System to suit custom forge
shops, and to develop a training program for the
industry.
Figure 2.
Analyze and Improve
“Quick-Start Approach to Jobshoplean” (figure3)
is a lean manufacturing implementation strategy
developed by Dr. Shahrukh Irani at The Ohio State
University. It combines the concepts and tools of
group technology, traditional IE techniques (eg.
flow process chart, flow diagram, etc.), lean tools
(value stream map, 5S, etc.) and Theory of
Constraints. In this case study, this approach is
used as the road map for analysis and improvement.
Key phases of this approach are discussed as
follows:
Method
The framework of the lean project includes four
parts: 1) Use “Quick-Start Approach to
Jobshoplean” to analyze and make improvements;
2) Create a lean culture through manager training
and discussion group; 3) Develop a lean training
program for all the employees; and 4) Document
the learning process and outcomes in order to
transfer to other shops in the forging industry. The
framework is illustrated as figure 1. The Gantt
chart of the whole project is shown as figure 2.
1. Data Collection
In order to form product families and select
appropriate product family as the target for
analysis, certain data is necessary:
1 Sales (quantity and dollar value): Sales data from
January, 2004 to March, 2007 was selected for
analysis. A weight of 0.3 was assigned to 2004,
2005, and 2006 each. A weight of 0.1 was assigned
to the first three months of 2007. The weighted
sales and quantities represent the current
production mix.
Collect Sales data from
the past fiscal year:
- Revenue
- Quantity
Obtain all Routings/
Bill of Routings
PFAS
T
Create Part
Fam ilies
Routings: The routings of the products is key
information to form product family. The routings
were put into a spreadsheet. However, information
in the ERP system was not up-to-date. For example,
some machines in the routings are obsolete or
replaced. Thus, an evaluation of the machines was
conducted to update the database. Lists of all
relevant operations & parts were given to the forge
shop manager, machine shop manager, and
secondary supervisor to update the information.
Pick a Part Fam ily
with Highest
Contribution
From this Part
Fam ily, pick a Part
(or Parts) with
sam e Routing
Obtain the layout of the facility and locate:
- Receiving
- Shipping
- Value-added workcenters featured in the routing/s
2. PFAST Analysis
Production Flow Analysis and Simplification
Toolkit (PFAST) is a library of computer programs
for machine grouping, part family formation, cell
layout and shop layout design. It helps analyze and
simplify material flows in make-to-order or other
high-mix low-volume manufacturing facility.
(Irani, Huang, Udai, Zhang, & Zhou; Irani, Zhang,
Zhou, Huang, Udai, & Subramanian, 2000). The
data obtained from the ERP system was converted
into an input file format for PFAST software. The
results are presented in many different forms
concentrating on different perspectives. According
to the Product-Quantity-Sales (P-Q-$) analysis of
PFAST results, there are 57 parts representing the
top 80% of the product mix. P-R Analysis Type II
shows that the 227 parts could be split into
hundreds of part families. Part families are formed
by taking into consideration the routing variances
which is the height of the dendogram.
Generate the Flow Diagram for the Part (or Parts)
Evaluate the Flow Diagram to identify:
- Flow Delays
- Eight Types of W astes
- Violations of the Principles of Design For Flow
- Absence of Line of Sight
- Crossflows and Backtracking in Flow Paths
- Large (>10ft) travel distances between consecutive operations ,
- etc.
Create a Flow Process Chart to identify Flow Delays and
Eight Types of W aste
Create the Value Stream M ap
for Detailed Evaluation of the Flow
Diagram
TEST
STOCK
ABRASI VE
SAW
1
1
1
1
N umber of shift:
N um ber of shift: 1
760
C/T= 20/hr
C/O= 10 m in
S/U= 15 m in
951
C/T= 1 day/ht #
C/O =
S/U=
Com pute:
- Value Added Ratio (VAR)
- M akespan (C)
- W eighted M akespan (Cw)
3. Part Family
In order to help select a part family for Quick-Start
Approach to Jobshop Lean, a supplement
technique, P-Q-T Analysis, was used. Besides the
quantity of each part, the frequency of order is also
considered. Sale manager was also requested to
label the parts as three categories- Runner,
Repeater, and Stranger, depending on the
frequency of customer order.
Help to identify the
Bottleneck
Perform TOC
Analysis at
Bottleneck
Identify and
Prioritize
Strategies for
Im provem ents
Project Schedule
to Im plem ent
Recom m endations
in O rder of Priority
Figure 3. Quick-Start Approach to Jobshoplean
2 Figure 4a. P-Q-T Analysis (1)
Figure 6. Routing of P/N 6504
4. Flow Diagram
Based on the routing in Figure 6, a flow diagram
of P/N 6504 was created (Figure 7). The flow
diagram shows how the parts flow through the
entire facility, from raw material storage at the left
side to the shipping area at the lower right corner.
From the flow diagram some problems in product
flow were identified. First, there are many
backtracks between forging shop and shipping area
which violate the “Design for Flow Principles.”
Second, the cross-flows in shipping area are so
complicated that need further examination.
Figure 4b. P-Q-T Analysis (2)
Figure 5. Part Families around P/N 6503& 6504
Figure 7. Flow Diagram
P/N 6503& P/N 6504 were selected as the part
family because: 1) the parts together represent
25.57% of the total revenue; 2) the parts are
repeaters and are pulled by customer through a
kanban system; 3) the parts have identical routings.
P/N 6504 was selected for preliminary analysis
due to production schedule. The routing of P/N
6504 is shown as figure 6.
5. Flow Process Chart
A flow process chart was created to study every
step of the flow process of P/N 6504. The flow
process chart captures a lot more detailed
information that helps to identify wastes. The steps
are documented as different categories- storage
(▼), transportation (→), operation (O), inspection
(■), and delay (D). For storage and delay, the lot
3 size, time spent, and place were documented; for
operations, setup time, cycle time and number of
staff were also documented; for transportation, the
distance and the method (forklift, cart, etc.) were
documented. Figure 8 shows the frequencies of the
different types of activities involved. Out of these
only the operations are considered value added.
Other activities can be seen as different types of
wastes.
identify the constraint and exploit the constraint.
For P/N 6504, the constraint is M227, milling. The
cycle time for P/N 6504 on M227 is 9.06 minutes.
It’s the same for P/N 6503.
In the past, Bula Forge usually forged the whole
work order (For example, 2,000 pieces of 6503)
and pushed the WIPs to the following operations.
However, during the 12 weeks of JS lean program,
the management team at Bula Forge had a major
change in thinking. An example follows. In May,
when Bula figured out there would be not enough
P/N 6503 and P/N 6504 for M227. They stopped
forging the batch and changed to forge parts
needed in order to keep M227 running. (P/N
6503& P/N 6504 are milled at the same time at
M227). The illustration is shown as figure 8. The
estimated benefits of this change are
:
z
Eliminate idle time of the M227 (constraint):
8hrs
z
Reduce excessive work-in-process
P/N 6502: $85,000 (75%)
P/N 6503: $50,700 (55%)
z
Reduce the flow time (average)
P/N 6503: 30 days => 12 days
(60% improvement)
Figure 8. Analysis of Flow Process Chart
6. Value Stream Map
A value stream map of P/N 6504 was created. The
value stream map presents the material flow and
information flow at Bula Forge. Both value-added
and non-value-added activities are shown on the
map, and the Value Added Ratio (VAR) was
calculated as 12.38%. This number means most of
the time spent during the process is
non-value-added.
Wayne, the president of Bula, commented on this
change, “We never make this kind of decision in
the past. Never. Through this lean program, we
now look at things differently.”
Figure 10. Change of the production schedule
Figure 9. Value Stream Map of P/N 6504
Create a lean culture through manager training
and discussion group
7. Theory of Constraints
Theory of constraints is usually applied by taking a
series of actions: 1) Identify the constraint; 2)
Exploit and elevate the constraint; 3) subordinate
the constraint; 4) Move to the new constraint.
Given the 12 weeks period, Bula Forge was able to
1. Lean Manufacturing Discussion Group
Making some improvements projects during a
short period might not be difficult. However,
sustaining the results and keep improving is a
4 different story. So, one major attribute of this JS
lean program is to form a “Lean Manufacturing
Discussion Group” that go through a series of
training activities. As a result, A group of 10 from
Bula, including president, vice president, shop
managers, sales manager, and department of
scheduling, human resource, purchasing, and
engineering, with the intern from OSU as
facilitator, met 1 hour per week for the first 8
weeks, and added 2 more hours for discussion for
the following 4 weeks.
Develop a lean training program for all the
employees
All the charts and tables created during the
analysis stage and all the outcomes of the
discussion group were used to develop a training
program for all employees. The curriculum is
shown as figure 12.
For Managers only
Module 4Read a Flow
Diagram
2. Readings, Discussion, and Group Activities
All of the Lean Manufacturing Discussion Group
members were required to study the assigned
readings before the meeting. The required readings
include:
„
The Goal: A Process of Ongoing
Improvement (2004), by Eliyahu M. Goldratt
„
Lean Thinking : Banish Waste and Create
Wealth in Your Corporation (2003), by
James P. Womack, Daniel T. Jones
„
The Toyota Way (2003), by Jeffrey Liker
Besides the required readings, some chapters are
selected as additional readings:
„
Learning to See (2003), by Mike Rother,
John Shook, Jim Womack, and Dan Jones
„
Toyota Talent (2007), by Jeffrey Liker and
David Meier
Module 6Read a value
stream map
Module 3- Identify a problem
Learning notes
for The Goal
Executive book
summary of The
Toyota Way
Module 2- Identify wastes
Module 1- Understand Lean Principles
Lean Thinking,
Ch.1-5.
Video Presentation: A program to initiate JobshopLean at Bula Forge
Figure 12.
Document the learning process and outcome in
order to transfer to other shops in the forging
industries.
The whole implementation process was
documented as a project report in word document.
Also, all the managers were interviewed and
videotaped. The video has been edited and
published as the instrument of knowledge sharing.
During the meetings, the intern instructed lean
concepts and tools using real examples at Bula, i.e.
the result of the analysis. And the group as a whole
had discussions around the topic and identified
opportunities for implementing the concept/tool.
After the meeting, the members conducted
individual or group projects and then presented the
results during the next meeting. Figure 11. shows
four improvement projects implemented during the
12 weeks. These projects are done by the
management team and the employees.
Results
The managers and employees were trained as lean
thinkers, and thus have the ability to identify
problems and solve the problems. Here are two
examples- one in shop floor, and one in office:
Example #1- Use 5S to reduce setup time
The discussion group selected grinding as the
target operation and videotaped all of the
operator’s actions when he prepared for grinding.
Then, the group reviewed the video together and
identified unnecessary transportations when
building a box due to improper location of boxes,
skids, and liners. The operator spent most of the
time walking around to get the three items from
three locations. So, the team did 5S on a shelf,
cleaned up all unused items, and placed the boxes,
skids, and liners at one location with proper
quantity (Figure 13-a)
Figure 11
5 Module 5Read a Flow
Process Chart
Estimated benefit of this improvement is shown as
follows :
• 5 minutes are saved when building 1 box
• 395 boxes built each year; so, 32 hours
are saved each year
• $12 hourly wage is saved per hour; so,
$384 is saved each year
• The resources can be used for
value-added activities
• The saving is more if benefits of the
employee, overhead cost, etc. are
considered
This improvement is very encouraging to the
group because no technology investment is made.
It’s simply through using the lean tools to identify
the wastes. And it only takes 1 hour to make it
happened.
The benefit of this improvement:
• Quality Dept will save 151 hrs per year –
20% savings
• Admin Dept will save 74 hrs per year –
33% savings
• Shop Floor will save 150 hrs per year –
60% savings
• Annual savings is over $5,000 per year.
Figure 13-a
Figure 14.
Recommendation & Conclusion
After 12 weeks analysis and training, more
opportunities for improvement were identified.
Also, there are many actions to take to ensure
continues improvement.
1)
Bula needs to keep updating the data in ERP
system such as routings, cycle times, setup times,
etc. This should be a discipline that every time
there is a change in the operation, the information
should be entered into the system immediately.
2)
Bula needs to keep reducing the setup time
by implementing SMED and thus reducing the
batch size. Bula can start this project by selecting a
part, videotaping all the actions of the setup, create
Figure 13-b
Example #2 Shorten the administrative lead time
The quality department used to spend a lot of time
on reporting scrap. Many actions are unnecessary
in the office. For example, copy and paste data
from one file to another file, and then record this
action in another file to make sure it’s done. Also,
there is a storage area for all the documents. By
creating a Microsoft Access database and
re-designing
the
process,
unnecessary
transportations and motions were eliminated.
6 a flow process chart and distinguish the actions as
either internal or external activities. Then, the
group can brainstorm to eliminate unnecessary
motions and shorten the changeover time.
3)
The sales manager can persuade the
customers adopt the lean concept and level their
demand. By having reduced setup time and having
stable small orders from customers, Bula can
implement the idea of heijunka and enjoy the
benefit of low inventory.
4)
As Bula has successful experiences using 5S
and visual management tools for the pilot project,
these concepts should be used all over the facility.
5)
Although in the short term it is not possible
to re-design the layout, move the machines, or
improve the line of sight efficiency, there’re still
ways to improve the communication between the
operations. For example, equipping the managers
and even the operators with walkie-talkies can
save time walking around.
6)
This lean project focused on P/N 6503 and
P/N 6504 only. The group should do similar
projects on other parts, create value stream map for
other parts, and create a Value Network Map to see
the whole picture.
7)
Since training is the major strategic issue at
Bula, Bula can explore the benefits of having the
shop managers and employees trained by TWI
program. Also, a training management system such
as ISO 10015 can be considered as the framework
of cross-training.
Reference:
Irani, S. A., Huang, H., Udai, T. K., Zhang, H.,
Zhou, J. “An Overview of the PFAST Program
Library”<http://www.iwse.osu.edu/ISEFaculty/
irani/research/PFAST/PFAST%20-%20General
%20Overview.htm>
Irani, S. A., Zhang, H., Zhou, J., Huang, H., Udai,
T. K. & Subramanian S. (2000). Production
Flow Analysis and Simplification Toolkit.
International Journal of Production Research,
38(8), 1855-1874.
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