30420130403001 by iaemedu


									 International Journal of Industrial Engineering       and Development (IJIERD),
INTERNATIONAL JOURNAL 4,ResearchSeptember - December (2013),ISSN 0976 –
                                                OF INDUSTRIAL ENGINEERING
 6979(Print), ISSN 0976 – 6987(Online) Volume Issue 3,                           © IAEME
ISSN 0976 – 6979 (Print)
ISSN 0976 – 6987 (Online)                                                  IJIERD
Volume 4, Issue 3, September - December (2013), pp. 01-12
© IAEME: www.iaeme.com/ijierd.asp                                       ©IAEME
Journal Impact Factor (2013): 5.1283 (Calculated by GISI)


              J. Arun1, S. Pravin Kumar2, M. Venkatesh3, A.S. Giridharan4
    UG Graduate, Department of Mechanical Engineering, Government College of Technology,
    UG Graduate, Department of Mechanical Engineering, Government College of Technology,
    UG Graduate, Department of Mechanical Engineering, Government College of Technology,
    UG Graduate, Department of Mechanical Engineering, Government College of Technology,


         An FMEA (Failure Mode and Effect Analysis) is a systematic method of identifying
 and preventing product and process problems before they occur. FMEAs are focused on
 preventing defects, enhancing safety, and increasing customer satisfaction. Ideally, FMEAs
 are conducted in the product design or process development stages, although conducting an
 FMEA on existing products and processes can also yield substantial benefits. FMEA is used
 in the manufacturing industry to improve production quality and productivity by reducing
 potential reliability problems early in the development cycle where it is easier to take actions
 to overcome these issues, thereby enhancing reliability through design. It is a method that
 evaluates possible failures in the system, design, process or service. In this paper, Failure
 mode and Effect Analysis is done on the process of Punching. A series of punching operation
 is done on various work pieces and the defects are found. Based on the evidence found, the
 ratings are given and risk priority number is given. Based on the RPN, the preventive
 measures are given. The FMEA is a proactive approach in solving potential failure modes.
 These works serve as a failure prevention guide for those who perform the punching
 operation and works towards effective punching operation.

 KEYWORDS: Failure Modes, Punching, Risk Priority Number, FMEA Table, Chipping.

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME


        In today’s market, the expectancy of the customer towards high quality, reliable and
cost effective products is really high. So this expectancy proves a burden for the
manufactures as they strive to satisfy the customers with defect free, reliable product. So the
manufacturers switch to a newer technique which helps them to achieve the expected
standards. The challenge is to design a quality and reliability product early in the
development cycle. Such challenges are met with latest techniques and strategies
implemented in both the design and product manufacturing. One such technique is Failure
Mode and Effect Analysis (FMEA). Failure Mode and Effect Analysis (FMEA) is used to
identify potential failure modes, determine their effect on the operation of the product, and
identify actions to mitigate the failures [1-2].

        FMEA is a tool originated by SAE reliability engineers. It continues to be associated
by many with reliability engineering. It analyzes potential effects caused by system elements
ceasing to behave as intended. The purpose of FMEA is to identify possible failure modes of
the system, evaluate their influences on system behavior and propose proper countermeasures
to suppress these effects. FMEA enhances further improvisation of both the design and
manufacturing processes in the future as it serves as a record of the current process in
formations [4-5]. FMEA is an engineering technique used to identify, prioritize and alleviate
potential problems from the system, design, or process before the problems are actualized
(According to Omdahl, 1988). What does the term “Failure Modes” imply? Lots of
definitions for this term can be obtained. According to the Automotive Industry Action Group
(AIAG), a failure mode is “the way in which a product or process could fail to perform its
desired function” (AIAG, 1995). Some sources define “failure mode” as a description of an
undesired cause-effect chain of events (MIL-STD-1629A, 1994). Others define “failure
mode” as a link in the cause-effect chain [3] (Stamatis, 1995: Humphries, 1994). To conclude
with we consider the term failure mode as any errors or defects in a process, design, or item,
especially those that affect the customer, and can be potential or actual. The term “Effect
Analysis” also invites various definitions. The effect analysis is “the analysis of the outcome
of the failure on the system, on the process and the service” (Stamatis, 1995: Humphries,
1994) [2-5]. To put it simply Effects analysis refers to studying the consequences of those

       FMEA is a tool that allows us to:

               •      Discover potential failures in a system, product or process
               •      Prioritize actions that decrease risk of failure
               •      Evaluate the system/design/processes from a new vantage point
               •      Guide design evaluation and improvement
               •      Troubleshoot and monitor the performance of systems

       Punching process is a stamping or pressing type of metal removal process in which
the product is formed by pressing the work between die [7]. The metal removal is by shearing
force between the work and the die. Various components contribute to the accuracy,

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

reliability of the product. When these components are defective, this leads to the failure of the
product. Some of the failures in the punching process are like Punch chipping, Slug jamming,
Galling etc. [7]. These result in unfavorable consequences like failure of the system or
production of inaccurate products. Hence it is essential to conduct a FMEA in this process so
that the failure is avoided totally or reduced. Prior notification of these failures can prevent
them by following control measures.


         The purpose of performing an FMEA is to analyze the product's design characteristics
relative to the planned manufacturing process and experiment design to ensure that the
resultant product meets customer needs and expectations. When potential failure modes are
identified, corrective action can be taken to eliminate them or to continually reduce a
potential occurrence [3-4]. In FMEA, failures are prioritized according to how serious their
consequences are, how frequently they occur and how easily they can be detected. Ideally,
FMEA begins during the earliest conceptual stages of design and continues throughout the
life of the product or service. Results can be used to identify high-vulnerability elements and
to guide resource deployment for best benefit. An FMEA can be done any time in the system
lifetime, from initial design onwards. The various steps in Process Failure and Effect
Analysis are as follows

•      Reviewing the process
•      List the potential effects and modes of failure
•      Assign a severity rating
•      Assign an occurrence rating
•      Assign a detection rating
•      Calculate the risk priority number (RPN) for each mode of failure
•      Take action to eliminate or reduce the high-risk failure modes
•      Calculate the resulting RPN as the failure modes are reduced or
eliminated [4].

       The blueprint (or engineering drawing) of the product and a detailed flowchart of the
operation are reviewed. The process parameters of the conducted tests are as follows:

Capacity                : 60 Ton
Maximum stroke           : 6"
Bed Area                : 42" X 32"
Speed                   : 40 Strokes per minute
Floor to Bed            : 33"
Dimensions              : 10'10" High, 8'6" RL, 6' FB
Weight                  : 15,000 Lbs
Tool used               : Tungsten steel
Work piece material : Silicon steel
Several trials are to be conducted with the above mentioned parameters.

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

    Fig 1: High Speed Press                 Fig 2: Defective product from punching process

                                    Burr formation

                         Fig 3: Burr formation in the punched product

        Based on the trials conducted the failures are listed. In this, previously recorded
failures are also added. The effects of these failure modes are also tabulated. These failure
modes and their effects are charted separately for the sake of calculating and assigning the
ratings and risk priority numbers. With the failure modes listed on the FMEA Worksheet,
each failure mode is reviewed and the potential effects of the failure should it occur are
identified. For some of the failure modes, there is only one effect, while for other modes there
may be several effects. This step must be thorough because this information will feed into the
assignment of risk rankings for each of the failures. It is helpful to think of this step as an if-
then process: If the failure occurs, then what are the consequences [4].

        The severity ranking is an estimation of how serious the effects would be if a given
failure did occur. In some cases it is clear, because of past experience, how serious the
problem would be. In other cases, it is necessary to estimate the severity based on the

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

knowledge of the process. There could be other factors to consider (contributors to the overall
severity of the event being analyzed) [4]. Calculating the severity levels provides for a
classification ranking that encompasses safety, production continuity, scrap loss, etc. user.
Each effect is given a severity number (S) from 1 (no danger) to 10 (critical). A failure mode
with severity number of 10 results in severe dissatisfaction of the customer and may even
result in the physical injury due to the failure. Severity ratings in the range of 4-6 result in
mild dissatisfaction of the customer whereas those in the range of 1-3 are not so severe and
may even be not detected [2-6]. Table 1gives the guidelines based on which severity ratings
were given.

                                  Table 1: Severity Ratings
      Severity Rating                                  Description
                           Failure is of such minor nature that the customer (internal or
                           external) will probably not detect the failure.
                           Failure will result in slight customer annoyance
             3-5           and/or slight deterioration of part or system performance
                           Failure will result in customer dissatisfaction and annoyance
             6-7           and/or deterioration of part or system performance.
                           Failure will result in high degree of customer
                           dissatisfaction and cause non-functionality of system
                           Failure will result in major customer dissatisfaction and cause
             10            non-system operation or non-compliance with regulations

        Occurrence ratings denote how often such failures occur. In this step it is necessary to
look at the number of times a failure occurs. This can be done by looking at similar products
or processes and the failure modes that have been documented [4]. A failure mode is given an
occurrence ranking (O), again 1–10. If a failure is inevitable or occurs often, then it is given a
rating in the range of 8-10. Those with mild occurrences are given 4-6 whereas those with
low or eliminated failure have 1-3 occurrence ratings [2-6]. Table 2 gives the occurrence
ratings based on which FMEA table is designed in this paper.

                                  Table 2 Occurrence Ratings
           Occurrence Rating                           Meaning

                     1               Failure eliminated or no know occurrence

                    2,3              Low or very few

                   4,5,6             Moderate or few occasional

                    7,8              High or repeated failure occurrence

                   9,10              Very high rate of failure or inevitable failures

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

        This section provides a ranking based on an assessment of the probability that the
failure mode will be detected given the controls that are in place. The proper inspection
methods need to be chosen. The probability of detection is ranked in reverse order. For
example, a "1" indicates a very high probability that a failure would be detected before
reaching the customer; a "10" indicates a low – zero probability that the failure will not be
detected [2-6]. Table 3 shows the guidelines based on which the detection ratings of a product
are given.

                                     Table 3: Detection Rating
        Detection Rating                                 Description
                1                 Very certain that the failure will be detected
               2-4                High probability that the defect will be detected
               5-6                Moderate probability that the failure will be detected
               7-8                Low probability that the failure will be detected
                9                 Very Low probability that the defect will be detected.
               10                 Fault will be passed to customer undetected

       The risk priority number (RPN) is simply calculated by multiplying the severity
ranking times the occurrence ranking times the detection ranking for each item.

Risk Priority Number = Severity × Occurrence × Detection

        The total risk priority number should be calculated by adding all of the risk priority
numbers. This number alone is meaningless because each FMEA has a different number of
failure modes and effects. The small RPN is always better than the high RPN. The RPN can
be computed for the entire process and/or for the design process only. Once it is calculated, it
is easy to determine the areas of greatest concern. There could be less severe failures, but
which occur more often and are less detectable. These actions can include specific inspection,
testing or quality procedures, redesign (such as selection of new components), adding more
redundancy and limiting environmental stresses or operating range. Once the actions have
been implemented in the design/process, the new RPN should be checked, to confirm the
improvements [1,2,6].

                          Table 4: FMEA Table for Punching Process
  S.                               Severity   Occurrence   Detection
        Problem       Effects                                             Causes          Solutions      RPN
  No                                Rating      Rating      Rating
  1      Punch      Deformation       7           6            8       High impact        Change         336
       Chipping &                                                            or            punch
          Point                                                        compressive      materials and
        Breakage                                                           failure       diameter
                    Leading to                    5           6        Misalignment                      210
                    downtime                                            resulting in    Check overall
                                                                       lateral forces   die alignment
                    Additional                    3           3        Part material    Use a retainer   63
                    die damage                                          movement          or punch-

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

                                            5          1                     Review die,       35
                                                             Poor material     press, &
                                                                control      feeder setup
                                            3          6      Excessive         Reduce         126
                                                               stripping     punch-to-die
                                                                 force           entry
                                                                              coatings to
                                                                             add lubricity

                                            2          2      Punch point                      28
                                                              hardness too      Verify
                                                                  low          hardness
                                            1          1       Improper                         7
                                                                 punch            Change
                                                                material           punch
                                                                selected          material
                                            8          2      Sharpening      Use Coolant,     112
                                                                damage       correct speeds
                                                                              and feeds for
                                            7          1                         Remove        49
                                                              Regrind burr     regrind burr
                                            1          1                         Increase       7
                                                               Tight die          material
                                                               clearance     Use Coatings
                                                                               and surface
                                            6          2                         Increase      84
                                                             Sharp corners     clearance in
                                                              on shaped      the corners of
                                                               punches          die button
                                            6          4                         Use shear     168
                                                               Flat punch       angles and
                                                                  face           use edge
                                            3          4       Improper            Triple      84
                                                                  heat        tempered for
                                                               treatment        high-speed
                                                                                and follow
                                                                                the guided
                                            4          3                          Cut-off      84
                                                               Improper        operation &
                                                                 punch          large point
                                                                stagger       first to enter
                                            7          2       Improper                        98
                                                               finish on
                                                              punch point    Ensure there
                                                             and/or punch    are no harsh
                                                                  face         grinding

   2    Excessive                   7       7          2       Incorrect        Restore        98
          burr         Stress                                  clearance        correct
                    concentration                                              clearance
                      at edges

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

                    Decreases               5          1                                         35
                                                                                Sharpen or
                   resistance to                              Worn tools
                                                                               replace tools
                     Shortens               4          1       Misalign            Check         28
                    fatigue life                              components         alignment

   3      Slug                     8        1          1                                          8
        Jamming      Punch                                     Tight die         Increase die
                    breakage                                   clearance           clearance
                                            6          1       Excessive       Change relief     48
                   Punch point                                land length       from counter
                   deformation                                                  bore to taper
                                                                                 Land length
                                                                                  should not
                                                                                 exceed four
                                                                               times material

                                            5          3      Taper in the     Verify there      120
                                                              land of the      is no reverse
                                                               die button       taper in the
                                                                                land of the
                                                                                 die button
                                            6          2      Inadequate                         96
                                                             taper relief in    Increase per
                                                               die button        side taper
                                            9          2       Worn die           Sharpen,       144
                                                                 button           replace,
                                                                               and/or change
                                                                                 die button
                                            9          3        Worn or                          216
                                                                 chipped         Sharpen or
                                                                  punch        replace punch
                                            5          1       Rough land           Use die      40
                                                              in die button     buttons with
                                                                                smooth wire
                                                                               cut, or ground
                                            3          2      Slug tipping          Check        48
                                                                                both sides of
                                                                                part material
                                            7          1       Obstruction     Examine slug      56
                                                              in slug relief         path
                                                                   hole            Consider
                                                                               increasing the
                                                                                  size of the
                                                                                relief hole in
                                                                                 lower plate

   4      Slug     Punch point     6        9          1      Bell mouth        Increase die     54
         Pulling   deformation                                wear in die        clearance
                    Excessive                                   button
                     wear on
                    punch and                                                     Check
                       die                                                      alignment
                                                                                Change die
                     Surface                                                     material

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

                     Broken                 8          2      Punch entry       Use slug       96
                   punches and                                 too deep          control
                      dies                                                       system
                                                                              Reduce punch
                                            3          3      Punch entry                      54
                                                                not deep          Increase
                                                                 enough        punch entry
                                            9          1     Excessive die      Reduce die     54
                                                                clearance        clearance
                                            3          2     Slug not held        Use slug     36
                                                               in the land         control
                                                                               Use vacuum
                                                                                slug sucker
                                                                                 Blow air
                                                                              center hole in
                                                                               Use negative
                                                                               taper in land
                                            3          1         Sticky            Check       18
                                                               lubricants       lubrication
                                            3          4      Not enough      Increase taper   72
                                                              relief on die    relief or use
                                                                               counter bore

   5     Punch      Reduced die    7        9          1       Tight die       Increase die    63
          Wear     performance                                 clearance        clearance
         and/or       Reduced                                                    Change
         Galling     punch and                                                    punch
                       die life                                                  materials
                      Requires              6          2      Punch entry                      84
                         heat                                  too deep
                    treatment of                                              Reduce punch
                        parts                                                      entry
                     High stress            3          2     Misalignment      Check die &     42
                   concentration                                                   press
                       in parts                                                 alignment
                                            4          2      Regrind burr       Remove        56
                                            6          1       Improper         Use flood      42
                                                             sharpening of     coolant, and
                                                                 punch            correct
                                                                               wheel speed
                                                                                & feed for
                                                                                steel type
                                            3          1       Improper          Change        21
                                                                 punch             punch
                                                                material        materials
                                            5          1     Sharp corners       Increase      35
                                                              on shaped        clearance in
                                                                punches       the corners of
                                                                              the die button
                                            4          1        Punch            Consider      28
                                                              surface too      punch finish
                                                                rough         improvements

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

                                            5          2        Lack of                        70
                                                                on part
                                                               incorrect        Check
                                                              lubrication     lubrication

   6   Punch Head     Increase in    10     5          2        Punch         Verify head      100
        Breakage     punch-to-die                              pumping         thickness is
                       clearance                                             properly fit in
                                                                               the retainer
                        Punch               6          3      Insufficient       Chamfer       180
                       breakage                               chamfer in        retainer to
                                                                retainer        clear head
                                                                                  fillet on
                      Excessive             4          7     Backing plate     Draw back       280
                       shear on                                too hard      backing plate
                     punches and                                                 to reduce
                         die                                                   hardness—
                                                                                RC 40-50
                     Deflection of          3          6      Head is too       Draw back      180
                      punch head                                 hard        head of punch
                                                                              to lower RC
                                            5          4      High impact    Increase head     200
                                                                 or high     diameter and
                                                              compressive        thickness
                                                              load on head        Increase

   7   Punch does     Increased      10     9          1       Incorrect         Restore       90
       not extract      delay                                  clearance          correct
                                            3          2        Lack of       Use proper       60
                                                              lubrication    lubrication or
                                            5          1         Tough            Revise       50
                                                               materials        clearance
                                            6          1      Ineffectual    Replace with      60
                                                               extraction      a spring or
                                                                system          reloaded

   8    Work part     Imprecise      10    10          1       Incorrect        Restore        100
       deformation   components                                clearance         correct
                                            2          2        Lack of       Use proper       40
                                                              lubrication    lubrication or
                                            6          1       Holes too      Reprogram        60
                                                                close in       alternate
                                                               sequence        punching

   9      Wear       Reduced tool    6      6          8       Speed too      Slow down,       288
                         life                                    fast          use more

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

                                            3          7      Hard material     Use higher      126
                                                                                 grade tool
                                                                               material, add
                      Dimensional           4          8        Improper       Increase feed    192
                      inaccuracies                            feed rate (too        rate
                                            4          5        Improper        Change to       120
                                                                punch-die        correct
                                                                  angle         punching
                                            4          5        Improper                        120
                                                                clearance       Give proper
                                                                  angle          clearance

     10   Reduced      High cost     4      7          6       Too much                         168
          tool life                                             shearing       Select proper
                                                              force during     tool materials
                                            5          6      Tough work           Select       120
                                                                material       premium tool
                                            4          6        Frequent       Resharpen the    96
                                                              resharpening          tool
                                                                 of tool        periodically


       From the table 4, which shows FMEA table for punching process, it is observed that
the punch chipping and point breakage due to the high impact or compressive force has the
highest risk priority number. This can be minimized by the proper selection of punch-die
materials and by maintaining the correct clearance between punch and die. The burr and slug
formations also have detrimental effect on the overall quality of the final product. These
undesirable developments can be curtailed by varying the feed rates and speed of the
machine. To reduce the breakage of tool and burr formation due to excessive feed rate and
high cutting speeds, we have to perform the process in rated speed and acceptable feed rates.
In order to produce the punched products without any deformations or distortions, better tool
and work holding devices are to be used. To reduce metal chipping, initial speed has to be
minimum and proper cutting speeds should be employed. The tool life can be increased by
proper lubrication, minimizing the wear and other parameter perfection has to be achieved.

4.        CONCLUSION

        Thus the high speed punching process in motor manufacturing section has been
analyzed and the expected failure modes have been noted. From the results of the critical
analysis made on the punching process, the failure modes with greater risk priority number
has been selected. The causes, effects and possible alternate solutions are given along with
the ratings and priorities of action that decrease risk failure. The risk priority numbers are
specified which indicates the necessity of care for producing defect-free punching process
and its products. Thus this process analysis will serve as a helpful tool to detect the failure

International Journal of Industrial Engineering Research and Development (IJIERD), ISSN 0976 –
6979(Print), ISSN 0976 – 6987(Online) Volume 4, Issue 3, September - December (2013), © IAEME

modes occurring in the punching process and also assures in the effective functioning of the
       This study provides a documented method for selecting a design with a high
probability of successful operation and safety. As a result of this approach, the system
development cost and time, the possibility of occurrence of same kind of failure in future are
reduced along with improved quality, reliability and safety of process/product. Consequently,
the productivity of the product is also increased. This approach can be well suitably applied
to consumer products like automotives, home appliances, etc., and other fields such as
manufacturing, aerospace, instrumentation, medical, chemical processing, etc.


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