28 ISE Magazine | www.iise.org/ISEmagazine
Competition has driven manufacturers to improve
product quality, time to market, cost structures, de-
livery, customer service and other measures. Because
it is essential to deliver products on the due date, we
offer an integrated framework to reduce preventable
delays in shipments and improve production process-
es using DMAIC and value stream mapping (VSM).
Based on the application case study, an analysis of the pro-
duction processes for a circuit board manufacturer used DMA-
IC – dene, measure, analyze, improve, control. The improve-
ment proposals were accomplished through the integration of
value stream mapping techniques in the analyze and improve
phases. The analysis reveals that implementing the integrated
approach would result in a 52% reduction in shipping delays
and a 66% reduction in the company production workforce.
This case study is about the production processes of the XYZ
company, a leading electronic contract manufacturer that pro-
vides custom design and engineering, prototyping and manu-
facturing of printed circuit boards, cable assembly and inte-
grated electronic systems. Its market sectors are healthcare and
medical, industrial electronics, aerospace and transportation.
This company produces different types of boards, one of which
was studied. The production process includes three STM lines,
four wave lines, line, selective solder, postwave, wash line, me-
chanical line, test line and ICT line (circuit testing). The most
crucial problem is a significant delay and inability to deliver
products before the agreed due date. This creates additional
and unnecessary costs and customer dissatisfaction.
Using the DMAIC approach
Six Sigma methodology combines a step-by-step analytical ap-
proach to solve a problem and improve the production process
with statistical tools. A series of well-dened steps, which con-
stitute DMAIC, DMADV (dene, measure, analyze, design,
verify), PDCA (plan, do, check, act) cycles and four quadrants
(measure, analyze, improve, sustain) are the key points to suc-
cessfully implement Six Sigma methodology (“Improve the
Extrusion Process in Tire Production Using Six Sigma Meth-
odology,” T. Costa, F.J.G. Silva and Luis Pinto Ferreira, 2017).
Every company can select and apply a proper methodol-
ogy and even combine them to improve its processes based
on the existing problem and its size. The most crucial point is
selecting the right methodology according to the company’s
needs and demands and applying it to the appropriate process.
DMAIC is an appropriate approach for the massive problem
and a proper methodology to implement in all types of manu-
facturing, healthcare, finance and service (“Quality Improve-
ment Methodologies for Continuous Improvement of Pro-
C
Enhance synergy of DMAIC,
value stream maps to boost production
A case study to improve shipping time in circuit board manufacturing
By Sanaz Eshraghi and Emmanuel S. Eneyo
June 2021 | ISE Magazine 29
duction Processes and Product Quality and Their Evolution,
Jevgeni Sahno and Eduard Shevtshenko, 2014). It is designed
to improve existing processes and use a problem-solving strat-
egy that follows a continuous improvement process. Figure 1
offers a brief explanation of DMAIC.
The DMAIC phases are:
Dene. The first and most crucial step where a team is cre-
ated that will be responsible for implementing the DMAIC
approach. The team must identify the following elements: De-
termining the problem; scope of the project; aim of the project;
deliverables and constraints.
This phase acts as a road map for the project and has a vast
influence on its success. A process map is usually prepared in
this phase. Also, the definition of problems helps create a good
understanding of issues that makes the job easier.
Measure. In this step, the existing system is measured and
valid and reliable standards are determined to monitor ad-
vances. Parameters and places of measurements are dened,
measured and classified. It will describe the points of process
quality and its costs with an accurate reflection of the actual
condition. A statistical perspective is needed on processes and
related problems. These measurements are conducted by dif-
ferent tools, such as the SIPOC method, descriptive statistics
and summary charts.
Analyze. In this stage, the measured parameters are ana-
lyzed. The team then isolates and verifies the critical processes
and determines the reasons for problems to be eliminated or
xed. The relation between the causes of defects and process
variability sources are studied; afterward, a potential list of the
problems is narrowed to vital cases. The relationship between
input and output that directly affect issues is identified, and
possible causes of process variability are verified. Some tools
such as PFMEA (Process Failure
Mode Effects Analysis), Pareto-Lo-
renz chart and Ishikawa diagram are
often used in this stage.
Improve. Improvement is
known as collaboration in the
course of the production process. In
this phase, appropriate solutions are
presented and implemented to im-
prove processes.
Control. The improved pro-
cesses are controlled after finishing
the improvement phase. The main
goal of Six Sigma methodology is
the constant observation of con-
tinuous improvement in processes
to sustain a desired level of quality.
In this stage, the measurement sys-
tem and potential verication pro-
cess are repeated to corroborate the
progress (Application of the Six Sigma Method for Improving
Maintenance Processes-Case Study,” Michał Zasadzień, 2017).
Value stream mapping
Value stream mapping is a method of visually mapping a prod-
uct’s production path. It can serve as a starting point to help
management, engineers, production associates, schedulers,
suppliers and customers recognize waste and identify its causes.
VSM visually maps the flow of materials and information
from the time products come in the back door as raw material,
through all manufacturing process steps and off the loading
dock as finished products.
Benefits of a VSM include: visualize material and associated
information flow; identify wasted efforts and practices; im-
prove all your processes from a systems perspective; and priori-
tize activities to reach your future state goal.
A typical mapping process consists of the following steps:
Determine the value stream. The mapping effort starts
with choosing the value stream to be improved and involves
extensive scoping efforts to identify the mapping activity’s
practical limits.
Create a current state VSM. The current state map
shows how things work. This is the “as-is” condition with all
of the problems, inefciencies and flaws displayed. The current
state map must be an honest depiction of what is happening.
Create a future state VSM. The future state VSM im-
proves the flow and reduces nonvalue-added activities in the
value stream. This future state must meet the customer re-
quirements and includes the necessary process improvements
to achieve the value stream vision.
Make an improvement plan. The final step is to de-
velop a detailed improvement plan that describes the neces-
FIGURE 1
The DMAIC approach
The process of define, measure, analyze, improve and control.
30 ISE Magazine | www.iise.org/ISEmagazine
Enhance synergy of DMAIC, value stream maps to boost production
sary improvements to realize the future state.
Mapping is simply a tool; implementing the
project is the key to success (Application Re-
search of Shortening Delivery Time Through
Value Stream Mapping Analysis,” Guo-
Qiang Pan, Ding-Zhong Feng and Mei-Xian
Jiang, 2010).
Value stream mapping is a commonly used
Lean tool that is appropriate when examining
the current state of a process to identify im-
provement opportunities in waste. It can help
identify activities that do not create value for
the customer, making it possible to reduce the
nonvalue-adding activities and create a more
efcient process. VSM helps increase the
awareness of waste, causes and consequenc-
es and knowledge on how to reduce waste
(Lean Six Sigma and Environmental Sus-
tainability: The Case of a Norwegian Dairy
Producer,” Daryl Powell, Sissel Lundeby, Lu-
kas Chabada, Heidi Dreyer, International Jour-
nal of Lean Six Sigma, 2017).
The VSM works well through the DMAIC
methodology and gives a broader perspective,
while Six Sigma tools allow a deeper under-
standing of the problem and its contributing
factors. This tool provides a more visual pic-
ture of the problem, highlighting the trials
importance compared to other issues in the
flow (“Integrating Value Stream Mapping
and DMAIC Methodology: A Case Study at
TitanX. Thesis,” Philip Gremlin, 2016). Integrating VSM and
DMAIC is a feasible approach to adopt their advantages and
avoid their disadvantages (“Integration of Value Stream Map-
ping with DMAIC for Concurrent Lean-Kaizen: A Case Study
on an Air-Conditioner Assembly Line,” Wei Guo, Pingyu Ji-
ang, Lei Xu and Guangzhou Peng, Advances in Mechanical Engi-
neering, 2019). The integration of DMAIC and VSM results in
a lot of needed information; therefore, it is time-consuming to
conduct projects using the two.
Case study at XYZ company
Dene. This is the first and foremost phase of the project that
acts as a road map. Several types of boards are produced in the
XYZ company. Some of the finished goods cannot be sent on
the due date, causing customer dissatisfaction and extra expen-
ditures. This phase aims to determine the problem, scope of the
project and the objective of the project.
According to the reviewed studies, SIPOC is a useful tool to
represent a more general illustration of how the selected prod-
ucts’ production is managed throughout the whole production
process. According to SIPOC, the inputs are different parts
of a board that are provided by vendors. The company orders
around 11 parts from five vendors and internally manufactures
the final product. Custom parts are ordered from foreign sup-
pliers. The vendors are presented in the suppliers’ section of
Figure 2, and components are shown in the inputs section. The
central part of this diagram is the processes section that shows
the 13 different processes required. The parts are assembled in
separate lines mentioned in Figure 2. If these processes are done
successfully, the final products would be ready for customer
submission. Thus, SIPOC is an overview of a workflow from
suppliers to customers.
Measure. This phase measures and analyzes the available
historical data to find the problem. Three products were se-
lected to investigate in this project because they have to pass
the same processes. A Pareto chart helps identify and prioritize
products based on the number of uncertainties during the last
year. The Pareto chart in Figure 3 (Page 31) is obtained from
the calculation of historical data to find the most vital area.
According to the Pareto chart, based on the 80/20 principle,
the “Vital Few” area is where the board No. 920042 is situated.
The argument was set earlier that this product has more delays
FIGURE 2
SIPOC diagram
Suppliers (vendors) and inputs (components) led to the processes section that shows
the 13 different processes required to create the product.
June 2021 | ISE Magazine 31
than other products. Thus, this is the main product that has to
be analyzed in the next phase.
Analyze. This phase of DMAIC consists of different tools
used to help define the area on which to focus on building a
solution in the improve phase. For this problem, value stream
mapping is an appropriate tool to investigate production pro-
cesses and find issues that cause shipping delays. A time study
is conducted for each process of the assembly lines and a VSM
prepared for current processes to produce board No. 920042.
Figure 4 shows the current VSM that board No. 920042
produced. The monthly demand for this type of board is 1,400.
The customer registers it in the range of 100-500 products in
different orders. When the quantity of an order is completed, it
is immediately sent to the customer; the company doesnt wait
to meet monthly demand. In the current VSM, an order with
300 products has been shown and four different local suppliers
provide 10 common parts monthly.
The company receives 43,400 parts to pro-
duce monthly demand for board No. 920042.
These parts reach the company in one to three
days. When all components are ready, a worker
creates a kit including the needed raw materials
monthly, based on the boards’ instruction, be-
cause the customer registers eight orders in one
day. The kit is transferred to the preproduction
line. Some of the raw materials need to be cut
down, according to instructions.
After this line, the kit is ready to go to the
SMT line, where most of the work is done on
the panel. After producing 300 panels, they are
transferred to the mechanical line to depanel-
ize the boards using the “guillotine” machine.
When 50 out of 300 panels are ready, they are
sent to the line, where specified parts are in-
stalled by hand and, after working on a board,
it is sent to the wave machine directly. The in-
stalled components are sol-
dered in the wave machine.
After this step, they are
sent to the postwave line to
solder the specied compo-
nents by hand. Here, 100
panels must stay for two days
because the soldering expert
for board No. 920042 is not
available and is working in
another line, which takes
about two days to finish
that job and come back to
postwave. There are some
soldering parts every expert
cannot do because a specific
skill set is required to solder
the specified boards. So, this
issue leads to considerable
lead time.
When work on 50 panels
is done in the postwave line,
the boards are sent to the
mechanical line to install
FIGURE 3
Pareto chart of shipments
The graph displays data of 3 products that suffer from delays. Based on the 80/20
principle, the key issues are with the first board.
0.00
20.00
40.00
60.00
80.00
100.00
120.00
0
5
10
15
20
25
30
35
Board #920042
Board #919002
Frequency of delay
Board #993007
Cumulative%
FIGURE 4
Current value stream map
A display of the processes used to create the XYZ company’s Board No. 920042.
32 ISE Magazine | www.iise.org/ISEmagazine
Enhance synergy of DMAIC, value stream maps to boost production
screw-on panels. They are
then sent to the postwave
line to check and revise
the current item with IPC
standards. After this step,
50 panels are inspected in
the inspection line for ap-
pearance, where an inspec-
tor checks soldering and
quality of soldering, veri-
fies the serial label and in-
spects all parts to rule out
the missing piece. In the
test line, a functional test is
conducted on the boards.
They are then ready to
send to the customer, but
after all of the steps, they
are sent to the inspection
line to be rechecked. Af-
terward, the finished goods
are sent to the packing line
and shipped to the customer.
The customer’s requirements are given as 1,400 boards No.
920042 per month; the company should be able to produce
about 350 every week to send orders on time. Yet it just pro-
duces about 250 a week because the processing time of the line
is 28 minutes, and panels wait about two days in the postwave
line for an expert. The bottleneck of this production process is
the postwave line.
To improve the production process, takt time should be
calculated. It is the rate at which you need to complete the
production process to meet customer demand and is equal to
the available time divided by demand. The average demand is
1,400 products monthly. The working time is 435 minutes in
every shift, and the company has three shifts that usually work
25 days a month. Based on this information, takt time is:
Takt time = Available Time/Demand
Takt time = (435 minutes, 3 shifts, 25 days)/1,400=23.30
minutes per unit
In Figure 5, the takt time, the production estimated time
and actual time were compared. The maximum cycle time is
28 minutes for the line, and it exceeds takt time. So, the line is
the bottleneck for the whole system, and the company cannot
meet the customers demand at the exact date. Also, the total
lead time is 12 days and six hours. These causes lead to delivery
delays and customer dissatisfaction.
Improve. This phase is to improve the production process.
In the current process, there is a loop between the mechanical
and postwave lines. A cell can be created to prevent this loop.
The four workers will do the responsibilities of mechanical,
line, wave and postwave lines in the new cell. By creating a cell,
lead time between these processes will be eliminated. Also, a
cell can be created for inspection, test and packing lines. These
changes will reduce the total lead time, and just one worker
will be assigned for every line in cells. Two workers can handle
the preproduction line instead of four. By hiring fewer work-
ers, the company can save its budget. A kanban system will
help this company to manage the inventory in the stockroom.
After kitting, the worker is responsible for writing kanban
cards for the used parts and put into the kanban box. The per-
son responsible for this box can get information about:
Inventor y.
• What kind of parts will the company need to order from
suppliers?
How many pieces will the company need to order from sup-
pliers?
This system can change the order system. Based on the
kanban box’s information, the company can order parts to
prevent stocking lots of features in the stockroom and avoid
a shortage. After kitting, the specied pieces that need cut-
ting based on the instruction will be sent to the preproduction
line’s supermarket. At the same time, panels will be sent to the
SMT lines supermarket to design and print a circuit on panels.
Supermarket and pull systems can be implemented between
the processes. The supermarket is a kanban stock point where
downstream customers can get the inventory they need as the
upstream supplier replenishes it. A pull system is a Lean tech-
FIGURE 5
Cycle time per unit
The takt time, the production estimated time and actual time are compared in the current VSM.
.
June 2021 | ISE Magazine 33
nique for reducing the waste of any production process. The
pull system will allow the company to start new work only
when there is customer demand.
When essential processes are done on the panels, they are
ready for the next line and will be placed in the supermarket
where the worker of the next line will get them. Both changes,
between processes, will prevent wasted time. Meanwhile, kan-
ban and supermarket systems will reduce the kitting processing
time from 45 minutes to 30 minutes. The changes are seen in
Figure 6.
The future state value stream map shows the production
cycle of the order is expected to be shortened from 12 days and
six hours to five days and 22 hours, representing a 52% reduc-
tion in shipping delays along with a reduction of the workforce
from 35 to 12, representing 66% in production cost. If workers
increase their operating speed and work based on the estimated
time, the maximum cycle time will be less than takt time. The
total processing time is ex-
pected to drop from 255.3
minutes to 206.9 minutes, a
19% reduction.
Control. After implement-
ing the mentioned solutions,
the company will establish a
control plan to monitor the
processes continuously, based
on the analysis of process vari-
ables under the changed prac-
tice. The related authorities
will then review the control
plan and the process for pos-
sible shorter production time,
lead time and improved cus-
tomer satisfaction.
This addresses delays in
manufacturing and sending
products to customers and
suggests the DMAIC ap-
proach to investigate all the
processes to find the root causes and present appropriate so-
lutions to reduce or eliminate the issues. Value stream map-
ping helps to understand and streamline production processes
and has proved to be a useful technique to shorten delivery
time and reduce production costs. In the XYZ company, it
is expected that using DMAIC and VSM will result in a 52%
reduction in shipping delays, a 66% reduction in the workforce
and decreased delivery time and production costs.
Overall, these changes can improve the production process
and reduce delivery delays. However, additional work still
needs to be investigated to find reasons for the long produc-
tion time.
Sanaz Eshraghi is pursuing her Ph.D. in industrial engineering at
Southern Illinois University. She received her bachelors degree in infor-
mation technology in 2021 and her masters degree in industrial man-
agement in 2016 from Islamic Azad University in Tabriz, Iran, and a
master’s degree in industrial engineering in 2020 from Southern Illinois
University Edwardsville. Her research interests include production auto-
mation and control and Industry 4.0.
Emmanuel S. Eneyo is a professor in the Department of Industrial
Engineering at Southern Illinois University Edwardsville. He has more
than 25 years of combined industrial work and consulting experiences
with several companies. He is a longtime member of IISE and the
Society of Manufacturing Engineers, and a member of Alpha Pi Mu
(Industrial Engineering Honor Society of America), Tau Beta Pi (Na-
tional Engineering Honor Society of America), Project Management
Institute and the American Society for Engineering Education. He is
also a licensed professional engineer in Illinois.
FIGURE 6
Future value stream map
The proposed improved process to create Board No. 920042 shows the production cycle of an order
shortened from 12 days to five.
.
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