The Process FMEA Tool for Boring Operation of Crankshaft to Enhance Quality and Efficiency

The Process FMEA Tool for Boring Operation of Crankshaft to Enhance Quality and Efficiency

Aniket R. Shitole Deshmukp, Aniket A.Deshmukp, Rohit N. Bhoge3, D.A. Mahajan4 1,2,3B.E. Student, Dept., of Mechanical Engg., NBN, Ambegaon, Pune, Maharashtra, India 4Professor, Dept., of Mechanical Engg., NBN, Ambegaon, Pune, Maharashtra, India

AbstractThe FMEA is a operative tool to detect and fully recognize potential failure modes and their causes, and the effects of failure on the system or end users, for a given product or process. It is an engineering analysis that systematically analyzes product designs or manufacturing processes , finds and corrects flaws before the product gets into the hands of the customer. This paper goals to identify and eliminate presentand potential problems from a manufacturing process ofcrankshaft in the company through the application ofFailure Mode and Effects Analysis (FMEA) for improving theconsistency of sub systems in order to ensure the quality whichin turn augments the foot line of a manufacturing industry.Thus the various possible causes of failure and their effectsalong with the prevention are deliberated in this work. Severitynumber, Occurrence number, Detection number and Risk PriorityNumber (RPN) are strictures, which need to bedetermined. Furthermore, some actions are anticipated whichrequire to be taken as quickly as possible to evade potentialrisks which aid to improve efficiency and effectiveness of crankshaft manufacturing processes and increase thecustomer satisfaction. The prevention endorsed in this papercan significantly decrease the loss to the industry in stretch ofboth money time and quality.

I.INTRODUCTION-

An FMEA should be the guide to the development of a complete set of actions that will decrease risk allied with the system, subsystem, and the component or manufacturing process to an satisfactory level. FMEA ultimately deals with identifying the failure modes and analyses of their effects on component.FMEA is sketchily classified into three major types, viz. System FMEA, Design FMEA, and Process FMEA. For System FMEA, the foremost objective is to improve the design of the system. While for Design FMEA, the impartial is to improve the design of the subsystem. Additionally, to improve the design of the manufacturing process, Process

FMEA is used.

1. Item- An item is the emphasis of the FMEA project. For a System FMEA this is the system itself. For a Design FMEA, this is the subsystem or component under analysis.For a Process FMEA, this is usually one of the specific steps of the manufacturing or assembly process under analysis, as signified by an operation description.

2. Function – A function is what the item or process is intended to do, usually to a given standard of performance or necessity.

3. Failure mode – A failure mode is the method in which the item or operation potentially fails to meet or deliver the anticipated function and associated requirements.

4. Effects An effect is the consequence of the failure on the system or end user.

5. Cause – A cause is the specific reason for the failure, preferably found by asking why until the root cause is determined. For Process FMEAs, the cause is the manufacturing or assembly deficit that results in the failure mode.

6. Severity- It is a ranking number linked with the most serious effect for a given failure mode.

   Table 1. Table for Severity

   II. CONCEPT OF FMEA-

   Failure Mode and Effects Analysis is a tool designed to recognize potential failure modes for a product or process, to assess the risk associated with those failure modes, to rank the issues in terms of significance and to identify and carry out corrective actions contrary to most serious concerns.

   In general, FMEA consists of the following points to be analysed

   4	Very Low	Nonconformance by certain items Noticed by most customers
   3	Minor	Nonconformance by certain items Noticed by average customers
   2	Very Minor	Nonconformance by certain items Noticed by selective customers
   1	None	No Effect

7. Occurrence- It is a ranking number associated with the likelihood that the failure mode and its supplementary cause will be present in the item being analyzed.

1. Risk Priority Number (RPN) – It is a numerical grade of the risk of each potential failure cause, made up of the arithmetic product of the three elements: Severity, Occurrence and Detection.

   i.e. R.P.N. = S*O*D.

2. Controls- They are the methods or actions currently planned, or are already in place, to reduce or eliminate the risk accompanying with each potential cause.

3. Recommended actions- They are the tasks proposed by the FMEA team to diminish or eliminate the risk associated with potential causes of failure.

Table 2: Table for Occurrence

8. Detection – It is a ranking number connected with the best control from the list of detection-type controls, based on the criteria from the detection scale.

Table 3. Table for Detection

1. Action Taken- It is the precise action that is implemented to reduce risk to an acceptable level.

2. Revised RPN It is Recalculation of Severity, Occurrence and Detection rankings after execution of recommended actions and thus calculation of revised RPN.

   Revised RPN= revised (Severity× occurrence × Detection).

   1. BASIC PROCEDURE FOR FMEA

      • Assemble the team.

      • Launch the ground rules.

      • Gather and review significant information.

      • Recognise the item(s) or process(es) to be analyzed.

      • Identify the function(s), failure(s), effect(s), cause(s) and control(s) for each item or process to be analyzed.

      • Evaluate the risk associated with the issues recognised by the analysis.

      • Prioritize and assign corrective actions.

      • Perform corrective actions and re-evaluate risk.

      • Allocate, review and apprise the analysis, as suitable.

   2. CASE STUDY AND FMEA ANALYSIS

      A crankshaft is main assembly part of the engine. It is found below the cylinder head. The crankshaft is an integral component of combustion engines. Piston are mounted on the crankshaft and it is responsible for motion of piston from T.D.C. to B.D.C.

      Manufacturing of crankshaft consists of number of processes. Starting from selection of material, Forging, Rough machining to Finish machining crankshaft travels through different machine to carry out specific operation.

      FMEA technique is applied to boring operation of crankshaft. Potential failure modes, potential causes , severity, occurrence, detection, recommended actions, etc are recorded based on the observations taken at factory floor. RPN is then calculated to analyze the risk. Recommended actions are prescribed based on the observations. Revised RPN number is calculated after recommended actions are partically implented on the shop floor.

      Table 4. Table for Fmea

      Subsys tem

      Potent ial Failur e Mode

      Potent ial Effect s of Failur e

      sev

      Poten tial Cause s of Failu re

      occ

      Current controls

      De t

      R.P. N

      Recomm ended Actions

      Respons ibility &Targe t completi on date

      Action Results

      Preventi on

      Detecti on

      Actions Taken

      Se v

      Oc c

      De t

      RP N

      Diame ter (43.05 +/- 0.13)

      Oversi ze

      Loose Fitme nt

      6

      1.Imp roper mount ing 2. Exces s run out 3. Impro per input stock 4. Mater ial Prope rties

      5

      1. Proper mountin g of workpiec e. 2. Improper Steady setting. 3. Deskille d Labour. 4. Improper maintena nce of MQC Sheet.

      8

      240

      1. Mountin g of Position Sensor. 2. Proper Fixture used. 3. Process Automat ed. 4. Checkin g of parts at fixed interval.

      6

      2

      4

      48

      Under size

      No Assem bly

      3

      1.Wor nout Tool insert. 2. Impro per Stead y. 3. Harde ned workp iece Mater ial.

      5

      3. From MQC Sheet.

      7

      105

      1.Optim um input stock set. 2. Proper fixyure used. 3. 5 in 1 checkup of parts for material propertie s.

      3

      2

      3

      18

      Depth (34.40 +/- 0.25)

      Oversi ze

      No assem bly

      5

      1.Sem iskille d labour . 2. Impro per tool. 3. Impro per Moun ting.

      4

      1.Appoin ting Skilled labour. 2. Periodic Tool replacem ent 3. Proper Mountin g of Workpie ce.

      1. By visual Detecti on. 2. Improp er surface finish. 3. by Visual inspecti on.

      7

      140

      1.Proces s automat ed on HMC. 2. Altering the material of tool. 3. Position sensors used for proper allignme nt.

      5

      2

      4

      40

      1. By Visual inspecti on.

      2. By visual inspecti on.

      3. By use of Gauge.

      4. from MQC sheet

      1. Use of Position sensor on HMC.

      2. Proper Steady setting.

      3. use of Skilled Labour. 4. Regular check for Material propertie s.

      1. Replac ement of tool insert.

      2. Proper oiling of steady. 3. Improper Material propertie s from MQC sheet.

      1. By Visual Inspect ion.

      2. By Visual Inspect ion.

      1. Maintai ning preffered input stock.

      2. use of fixture. 3. Regular Checkup of material priopertie s from sample.

      1. Use of Automati on.

      2. Use of Hard material for tool.

      3. Use of Position sensors.

      Under size

      No Assem bly

      5

      1.Imp roper tool insert. 2. Impro per input stock. 3. Faulty measu ring instru ment.

      4

      1. Visual Detecti on. 2. Stock setup given. 3. Using Gauges .

      6

      120

      1.Positio n sensor used. 2. Validati on of porgram prior to operatio n. 3. Use of digital measuri ng instrume nt.

      5

      1

      4

      20

      Runou

      Excess

      Out of

      8

      1.Imp

      5

      1.Check

      1.Free

      6

      240

      1.Proper

      1.Accura

      8

      2

      3

      48

      t with

      runout

      Rotati

      roper

      rotation

      Run of

      Fixture

      te

      respec

      on

      Holdi

      of

      workpi

      designing

      Fixture

      t to

      ng of

      workpiec

      ece and

      .

      Designe

      Center

      workp

      e with

      by

      2.

      d.

      ing

      iece

      respect

      visual

      Automati

      2. Used

      (0.025)

      in

      to center.

      detecti

      c tool

      Automat

      Chuck

      2. Tool

      on.

      changer

      ic tool

      .

      change at

      2. By

      from

      changer

      2.Imp

      regular

      visual

      Pallet.

      and

      roper

      interval.

      detecti

      3. Fixed

      ensured

      tool

      3. Check

      on.

      Stock

      change

      chang

      for

      3.

      setup

      of tool

      e

      Excess

      Excess

      using

      after

      freque

      stock.

      Heatin

      automati

      specific

      ncy.

      4. Proper

      g of

      on.

      lot.

      3.

      maintane

      workpi

      4. Use of

      3. Fixed

      Exces

      nce of

      ece.

      Presized

      stock

      s

      measurin

      4.Using

      measurin

      setup by

      Stock.

      g gauge.

      Presize

      g system.

      use of

      4.

      d

      5.

      program

      Faulty

      5. Ensure

      Measur

      Process

      ming.

      Meas

      oiling of

      ing

      automati

      4. Used

      uring

      steady at

      unit.

      on.

      presized

      Gauge

      regular

      5.

      measuri

      .

      interval.

      Excess

      6.

      ng

      5.

      6.

      Heat

      Process

      system.

      Impro

      Appoint

      Genera

      automati

      5.

      per

      skilled

      tion.

      on.

      Process

      Pressu

      Labour.

      6.

      Automat

      re and

      Visual

      ed.

      Settin

      inspecti

      6.

      g of

      on.

      Process

      Stead

      Automat

      y.

      ed.

      6.

      Deskil

      led

      labour

      .

      Surfac

      Rough

      Bearin

      7

      1.Too

      5

      1.Tool

      1.Chec

      6

      210

      1.Tool

      1.Tool

      7

      2

      2

      28

      e

      Surfac

      g

      l

      replacem

      king of

      change

      change

      Finish

      e

      wearo

      wearo

      ent.

      tool

      after

      after

      Finish

      ut

      ut.

      2.

      insert.

      regular

      regular

      2.

      Maintain

      2.

      interval.

      interval

      Exces

      optimum

      Excess

      2.

      from

      s

      feed rate.

      heating

      Process

      ATC.

      feedra

      3.

      of

      automati

      2.

      te.

      Maintain

      workpi

      on and

      Proper

      3.

      Optimu

      ece.

      proper

      program

      High

      m speed.

      3.

      program

      ming.

      speed.

      4. Depth

      Visual

      ming.

      3.

      1. Replac ement of tool insert.

      2. Proper input stock setup.

      3. Use of accurate measurin g instrume nt.

      1. Use of sensor for detection of improper tool insert.

      2. Proper program ming for cnc.

      3. Use of Digital measurin g instrume nt.

      				4. Exces s depth of cut. (50 micro n)		cut below 50 micron is preffered .	detecti on. 4. Visual detecti on.			3. Process automati on. 4. Proper program ming.		Optimu m speed maintain ed and process automise d. 4. Process automise d.
      	High Surfac e Finish	Bearin g Failur e	5	1.Des killed labour . 2. Dama ged tool Insert. 3. Depth of cut of 0.1m m. 4. High speed of rotatio n.	4		1. Visual detecti on. 2. Visual Detecti on and excess feed. 3. Excess heating pf workpi ece. 4. Visual detecti on.	5	100			3. Process automise d. 4. Process automise d.	5	1	3	15

      1. Appoin tment of skilled labour.

      2. tool replacem ent.

      3. Proper Adjustm ent. 4.Mainta ining Optimu m speed.

      1. Process Automati on.

      2. Tool change after regular lot.

      3. Proper Prgramm ing and process automati on.

      4. Proper program ming and process automati on.

      1. Proces s automise d.

      2. Tool chnaged after specific lot of machini ng.

   3. CONCLUSION

FMEA for Boring operation as been validated. FMEA is continuous improvement tool used in manufacturing unit. Continuous record of failures and actions taken should be noted duly and reqired changes can be made in the FMEA report. FMEA saves both, time and money of company. FMEA report has to be followed by the employer on the shop floor. It helps to eliminate the problem in less period of times hence saving time. Failure Mode,Effects and Criticality Analysis (FMECA), advancement in FMEA can been used for criticality analysis.

REFERENCES

1. Gunjan Joshi and Himanshu Joshi, FMEA and Alternatives v/s Enhanced Risk Assessment Mechanism,International Journal of Computer Applications (0975 8887),Volume 93 No 14, May 2014.

2. Failure mode and effects Analysis, http://en.wikipedia.org/wiki/Failure_mode_and_effects_analysis, 2014.

3. A. A. Nannikar, D. N. Raut, M. Chanmanwar, S. B. Kamble and

   D.B. Patil, FMEA for Manufacturing and Assembly Process,International Conference on Technology and Business Management,pp.26-28, March 2012.

4. Ping-Shun Chen and Ming-Tsung Wu, A modified failure mode and effects analysis method for supplier selection problems in the supply chain risk environment: A case study, Computers & Industrial Engineering, Issue 66, pp. 634642, 2013.