International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 12, December 2013)
Design Optimization of Failure Mode for Improving Quality
Control on the Engine Assembly Line
Shalom Akhai1, Piyush Pandita2
1
2
Assistant Professor, Undergraduate Student Mechanical Engineering department, PEC University of Technology
So, FMEA gives us a varied view on how to incorporate
a very fundamental tool to ensure the quality of the product
lies in safe limits.
Abstract-The present paper discusses the importance laid
on increasing quality is difficult to avoid in Industry. The
industry needs quality as a selling point in order to ensure
survival in a competitive world which serves as a difficult
place to exist in. So, the manner of improving quality in the
products is ensured by the work done on reducing the defects
by improving the process. The analysis of failure modes of a
particular operation is the method adopted to map the
uncertainties in the product, at the end of the assembly stage.
In order to kill or root out the errors at the basic stage, the
FMEA is the most essential tool which provides an authorized
way to look at the contribution of various factors into the
major calamity affecting the product. Hence in the coming
years such an analysis must be made central to the plans of
the organization, as it allows the managers, operators and
even the auditors to ensure that they reach the ultimate aim of
the defect free product..
II. NEED FOR QUALITY CONTROL
A. Improving the product
The initiative for driving ahead of the competitors rests
on how sound the quality of the product is. Thus in order to
improve the sales and the brand value, an unimpeachable
focus has been placed on improving the quality of the
products.
B. Maintaining the system at a reputable level
In order to prevent the defects from emerging from
within the system, the quality of the process needs to be
monitored, and thus an effective FMEA makes for a very
ordered set of batches in production. The products are not
only self attuned to the requirements at the next operation
but also add to the requisite quality in the process/operation.
Keywords— quality control, failure mode, RPN; risk
priority
I. INTRODUCTION
Whenever we have a series of operations dependent on
one another, a defect at later stage may well be traced down
to the failure to conform to the standard procedures for
performing an operation which directly or indirectly affects
the outcome/product of the next operation or the subsequent
operation. This is where the above mentioned quality
control measures are adopted to ensure we are able to detect
possible causes of failures in each and every operation
performed on the assembly line. The study is based on the
engine assembly line, where operations were followed each
and every stage and. A FMEA is an analytical tool that uses
a disciplined technique to identify and help eliminate
product and process potential failure modes. For many
years, QS 9000 and ISO/TS-16949:2002 has mandated
FMEA, as a result many companies prepare FMEA for the
sake
of
customer
requirement
or
auditor.
Producing FMEA as document without coming up with any
action plan, or just documenting the existing action is not an
effective way of doing FMEA.
The real impact of the FMEA is if it is used as an
important tool in the quest of improving the quality of
product by going through the step of improving the
processes and operations involved.
III. PREPARATION OF THE FMEA FOR A SPECIFICALLY
WRONG OPERATION
The operation on the engine assembly line which was the
most affected in terms of errors and defects was the fitment
of the gear level. The operation was of utmost importance as
the attachment of the gear stick on the level was the next
operation, which in turn would have made a very harmful
impact on the overall functioning of the vehicle (truck).
Also, these steps are done in order to secure our systems
from any internal human errors.
A. Operation on Gear Lever Bracket Fitment
B. The fitment of the gear lever bracket on the engine is an
operation which is being tapped. The preparation of
FMEA involved the studying of various causes of
failure and then grading them according to the weighted
average in terms of the effect that they would cause if a
failure occurred.
201
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 12, December 2013)
customers (>50%)
C. The follow through of the PFD results in the formulation
of the FMEA, where we decide on the RPN (Risk
Priority Number). The RPN is a product of three values
namely:
Occurrence rating
Detection rating
Severity rating
processed
Appearance or
audible noise,
vehicle operable,
item does not
confirm and
noticed by
TABLE 1
OPTIMIZED AND STANDARDIZED RANKING TABLE FOR
CALCULATING THE RISK PRIORITY NUMBER
EFFECT
CRITERIA:
SEVERITY OF
EFFECT ON
PRODUCT
(CUSTOMER
EFFECT)
R
A
N
K
EFFECT
before it is
CRITERIA:
SEVERITY OF
EFFECT ON
PROCESS
(MANUFACT
URING /
ASSEMBLY
EFFECT)
2
Minor
disruption
Slight
inconvenienc
e to process,
operation, or
operator
discriminating
customers
(>25%)
No effect
No discernable
effect
1
No
discernible
effect
IV. FMEA (FAILURE MODE AND EFFECTS ANALYSIS)
Important Points about PFMEA
Loss of secondary
function
(vehicle
inoperable, does
not
Loss or
degradation of
secondary
function
Appearance or
audible noise,
vehicle operable,
item does not
confirm and
noticed by most
customers (>75%)
Annoyance
6
Moderatedis
ruption
affect safe vehicle
operation
Degradation of
secondary
function ( vehicle
operable, but at
reduced level of
performance)
reworked
offline and
accepted
A portion of
production
run may be
reworked
offline and
accepted
5
100% of
product may
have to be
reworked in
station before
it is processed
4
Appearance or
audible noise,
Major
disruption
vehicle operable,
item does not
confirm and
noticed by most
 Implementing better prevention for causes will reduce
occurrence – hence reduces the losses
 Implementing better detection of failure mode will
ensure that customer is not suffered
 Implementing better detection of causes will reduce
the occurrence of failure modes
 First preference in PFMEA is to reduce OCC and next
is to improve DET
 Don’t dictate cut-off RPN number, decide based on
Pareto
 While looking at supplier FMEA see whether all the
ISV’s are identifies as FM
 While writing potential effects on end user / customer,
collect input from DFMEA
 Ensure that FMEAs are updated
 When doing a PFMEA, assume design is right. While
doing DFMEA assume that process is right
 FMEA should lead to improvement in quality control,
it is not just a document for auditors /customer.
 FMEA should lead to improvement in quality control,
it is not just a document for auditors /customer.
100% of
product may
have to be
D. Now the following operation shown was taken under
specific consideration: Figures and Tables
The FMEA shown above mentions the evaluation of the
failure modes that were identified through data collection
and observation at the engine assembly line. The modes
have their potential effects written in the next column with
a risk assigned to each with the help of the standardization
guide.
A portion of
production
run may
3
be reworked
in station
202
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 12, December 2013)
At the end we calculate the RPN (Risk Priority Number)
to get to the most dangerous part of the operation in terms
of contributing to the defect.
[5]
Bucuvalas, Quality assurance tools for use with source code and a
semantic model.
V. CONCLUSION AND DISCUSSION
 Implementing better prevention for causes will reduce
occurrence – hence reduces the losses.
 Implementing better detection of failure mode will
ensure that customer is not suffered.
 Implementing better detection of causes will reduce
the occurrence of failure modes.
 First preference in PFMEA is to reduce OCC and next
is to improve DET.
 Don’t dictate cut-off RPN number, decide based on
Pareto.
 While looking at supplier FMEA see whether all the
ISV’s are identifies as FM.
Figure 1. The FMEA made for the given operation
 While writing potential effects on end user / customer,
collect input from FMEA.
 When doing a PFMEA, assume design is right.
 While doing DFMEA assume that process is right.
 FMEA should lead to improvement, it is not just a
document for auditors /Customer.
VI. FUTURE SCOPE
The quality control is a viable and vouched for
ingredient in the manufacturing systems of the companies.
Even in the future it is going to be of utmost importance..In
the times to come, quality is going to be the measuring tool
while comparing the products of two brands, thus such
quality control which involves analyzing data to get the
defects out of the system, is going to be of massive
advantage to the company that implements it..The use of
tools like FMEA allows the company to refresh its own
system of manufacturing and thus get better self
dependency. This also lays a strong foundation for the
future.
Figure 2. Loosening of the previously fastened bolts
REFERENCES
[1]
[2]
[3]
[4]
Paliska, G.; Pavletić, D. & Soković, M., APPLICATION OF
QUALITY ENGINEERING TOOLS IN PROCESS INDUSTRY
Steven Silverman & Lori Silverman, Using Total Quality Tools For
Marketing Research: A Qualitative Approach For Collecting,
Organizing, and Analyzing Verbal Response Data
Jack Peckar, Total Quality Management: Guiding Principles for
Applications
Paliska, Pavletic, Sokovic ,Quality tools- systematic use in process
industry, JAAME, November 2007
Figure 3. The loose tightening of bolts in the grooves.
203
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 12, December 2013)
Figure 4. Tightening of the bolts on the gear lever using the
appropriate torque
204