Experimental Investigation on Reducing the Quality Concern of Blow-Hole In Cylinder Block


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Experimental Investigation on Reducing the Quality Concern of Blow-Hole In Cylinder Block

Mohan. Y [1], Deepak S [2], Sudharsan R [3], Yashvanth U [4]

Department of Automobile Engineering Hindustan Institute of Technology and Science, Chennai, Tamil Nadu

Abstract:- In this research paper an Automotive component having Blowhole defect has been taken. The said component is an Automotive 3-Cylinder engine block with displacement of 799cc. since it is the important component it has to be of the higher quality so there is no room for shortcuts. In this paper various analysis of part is done using Quality Control tools (QC Story). In order to be efficient and effective we follow Plan-Do- Check-act (PDCA) cycle for identifying the optimum process parameter in order to improve the casting quality and reduce the rejection rate at factory end. From the Pareto chart and Cause & Effect diagram, the major causes are prioritized and controllable factors identified.

Keywords: Blow-hole, QC Story, Pareto chart, Cause & Effect diagram, PDCA.

  1. INTRODUCTION

    Die casting process is a process used in order to manufacture complex shapes. Cylinder block is made of High Pressure Die Casting (HPDC). Defect rate in casting process increase the loss of production time and cost to the company. In this paper, we going to solve the real time problem faced by one of the manufacturing company. The major defect identified is Blow-hole near gating area. This Blow-hole leads to major leak in the casting. Blow-hole is found after machining of 2mm in Cylinder block. The defects were identified by past production lots and reports provided by the quality department. The Blow-hole defect can be minimized by taking precautionary measures in casting process. Blow-hole in the Cylinder block leads the casting to scraps.

    The manufacturing company is Automotive MNC company, here they are facing high rejection rate in Cylinder block, failing to deliver the required quantity on time.

    Fig 1, shows the foundry stage PPM rejection trend plotted for the months of Sep-Nov FY18. The gap in Sep is 2000 PPM, in Oct is 3706 PPM, in Nov is 4529 PPM. The overall average PPM for a period of Sep-Nov FY18 is 13,500 PPM. The actual rejection PPM doesnt meet the target PPM even in a single month. Hence it seemed like a chronic problem.

    Sep18

    Oct18

    Nov18

    Average Total

    Inspected in nos

    17,000

    17,000

    17,000

    17,000

    Scrapped in nos

    210

    233

    247

    230

    Rejection in PPM

    12,000

    PPM

    13,706

    PPM

    14,529

    PPM

    13,500

    PPM

    Table 1: Rejection trend table.

  2. METHODOLOGY FOR BLOW-HOLE ANALYSIS

    QC Story is a methodology in Total quality management (TQM), which is intended to solve a problem. QC Story is based on the principle of Plan-DO-Check-Act (PDCA). Generally, a Qc Story is a 7 steps procedure, but elaborated to 9 steps for better efficiency.

    First all the rejection data of casting is collected from the quality department. Then by using the QC tools such as Pareto chart and Cause & effect diagram the work is carried out. Fig 2, shows the QC story procedure

    Fig 2: QC Story procedure.

    16,000

    14,000

    12,000

    10,000

    8,000

    6,000

    4,000

    2,000

    0

    Cylinder block – Foundry stage Rejection trend

    13,706 14,529

    12,000

    10,000 10,000 10,000

    SEP OCT NOV

      1. Pareto Chart

        The Pareto analysis of cylinder block was carried out for the period of 3-months from September-November FY18. It is inferred that Pareto analysis prioritizes Blow- hole defect as top priority contributing to 65.36% of overall defects, followed by oil leak, water leak and others being 17.97%, 10.29% and 6.38% respectively. Fig 3, shows the defect rate for the 3-months.

        Target PPM Rejection PPM

        Fig 1: Foundry stage rejection trend.

        CYLIBER BLOCK OVERALL DEFECT RATE SEP-NOV FY'18

        700 93.62

        83.33

        100.00

        100.00

        95.00

        90.00

        Cause effect diagram is one of the approaches to enumerate the possible causes. Fig 5, shows the cause-effect diagram with significant problem.

        600 85.00

        80.00

        75.00

        500

        QUANTITY

        QUANTITY

        400

        300

        200

        100

        CUMMULATIVE %

        CUMMULATIVE %

        65.36

        451

        124

        71 44

        70.00

        65.00

        60.00

        55.00

        50.00

        45.00

        40.00

        35.00

        30.00

        25.00

        20.00

        15.00

        10.00

        5.00

  3. DATA MEASUREMENT PLAN

    0

    BOTTOM FACE OIL LEAK WATER LEAK OTHERS

    0.00

    QUANTITY 451 124 71 44

    PARETO 65.36 83.33 93.62 100.00

    DEFECTS

    QUANTITY PARETO

    Fig 3: Overall defect rate September-November FY18

    Data collection was done to know about the current scenario of the rejection trend of the component and then it was further segregated to know major error producing area and then that data was converted into Pareto chart. Fig 4, shows the location wise Blow-hole defect for 3-months September- November FY18.

    BOTTOM FACE DEFECT LOCATION

    97.12

    450

    91.35

    99.56 100.00

    100.00

    90.00

    400 81.37

    Process/ Input

    Operational definition

    Data source & location

    Sample size

    Who will collect the data

    Abnormal injection curve.

    To investigate the effect of process parameter setting.

    Daily testing parameter report.

    10

    samples from a lot.

    Technician.

    Low metal pressure.

    Temperature taken at Spout of press pour at which a casting metal is poured.

    Daily testing parameter report.

    2-3

    times in a single lot.

    Technician.

    Soldering mark in defect location.

    Observed from the Cylinder block casting.

    Daily log sheet.

    2-3

    times in a single lot.

    Technician.

    Gate area temperature high.

    Temperature taken at gate area of the casting.

    Daily testing parameter report from the lab.

    2-3

    times in a single lot.

    Technician.

    td>

    Technician.

    Process/ Input

    Operational definition

    Data source & location

    Sample size

    Who will collect the data

    Abnormal injection curve.

    To investigate the effect of process parameter setting.

    Daily testing parameter report.

    10

    samples from a lot.

    Technician.

    Low metal pressure.

    Temperature taken at Spout of press pour at which a casting metal is poured.

    Daily testing parameter report.

    2-3

    times in a single lot.

    Technician.

    Soldering mark in defect location.

    Observed from the Cylinder block casting.

    Daily log sheet.

    2-3

    times in a single lot.

    Gate area temperature high.

    Temperature taken at gate area of the casting.

    Daily testing parameter report from the lab.

    2-3

    times in a single lot.

    Technician.

    68.29

    350

    80.00

    70.00

    300

    QUANTITIY

    QUANTITIY

    60.00

    Table 2: Data measurement table.

    250

    CUMMALTIVE %

    CUMMALTIVE %

    50.00

    200

    150

    100

    50

    0

    42.57

    192

    116

    59 45 26 11 2

    40.00

    30.00

    20.00

    10.00

    0.00

    Table 2, shows the data measurement plan for the performance measure such as Abnormal injection curve, Low metal pressure, Soldering mark in defect location, Gate area temperature high. Data source, sample size, data

    G4 G1 G2 G3 G8 OTHERS G5

    Quantity 192 116 59 45 26 11 2

    Pareto 42.57 68.29 81.37 91.35 97.12 99.56 100.00

    LOCATION

    Quantity Pareto

    Fig 4: Location wise Blow-hole defect Sep-Nov FY18.

      1. Cause & Effect diagram

    The various causes for Blow-hole defect was found using Brain storming, significant reasons were identified. The systematic methodical approach is being devised for controlling the defect rate.

    Fig 5: Cause effect diagram.

    collection techniques are indicated.

  4. ACTION TAKEN

    Fig 6: Blow-hole defect cut piece.

    As shown in the above fig 6, the blow-hole was found at the gate area location on the Cylinder block casting. G1 and G4 gate location was found Significant and the root cause of the problem was identified.

    The corrective action was taken in the die since the cooling is insufficient at defect location. The temperature at G1 and G4 was high and it corrected by increasing the depth of cooling points in the die.

    Table 3: Change in Die measurement

    Die Temperature Before & After

    BLOW-HOLE DEFECTAFTER CORRECTION IN DIE

    Diameter

    Depth

    Before

    8 diameter

    165mm

    After

    8 diameter

    190mm

    Diameter

    Depth

    Before

    8 diameter

    165mm

    After

    8 diameter

    190mm

    4.5

    4 4

    4 4

    3

    3

    3

    3

    3 3

    2

    2

    2

    3

    2

    4 4

    4 4

    3

    3

    3

    3

    3 3

    2

    2

    2

    3

    2

    4

    3.5

    3

    2.5

    2

    1.5

    1

    0.5

    0

    160

    140

    120

    100

    80

    60

    40

    20

    0

    G1, 142

    G1, 109

    G2, 106

    G3, 104

    G4, 102

    G5, 106

    G6, 106

    G1, 109

    G2, 106

    G3, 104

    G4, 102

    G5, 106

    G6, 106

    G2, 107 G3, 109

    G4, 135

    G5, 105 G6, 106

    28-Jan 29-Jan 30-Jan 31-Jan 01-Feb 02-Feb 03-Feb 04-Feb 05-Feb 06-Feb 07-Feb 08-Feb 09-Feb 10-Feb 11-Feb

    Fig 8: Rejection trend of January-February FY18.

    Current level of Blow-hole

    1.35% (Average of 3 months)

    Achieved level of Blow-hole

    0.94%

    Reduction in defects

    0.41%

    Production plan / month

    17.000 nos

    Number of rejection / month

    160 nos

    Cost saving / month

    7.68,000

    Current level of Blow-hole

    1.35% (Average of 3 months)

    Achieved level of Blow-hole

    0.94%

    Reduction in defects

    0.41%

    Production plan / month

    17.000 nos

    Number of rejection / month

    160 nos

    Cost saving / month

    7.68,000

    5.1 Cost benefit analysis

    G1 G2 G3 G4 G5 G6

    Temperature before correction Temperature after correction

    Fig 7: Temperature Before & After Correction in Die.

  5. PROJECT RESULT

The Blow-hole defect analysis was carried out using QC tools and the 3-month data was collected from the log sheet available at the company. Using that the rejection trend was found and the Blow-hole contributes about 65.36% defect rate from all other defect. So the significant cause was found and corrected.

Fig 8, shows the Rejection trend for the of January-February FY18. The Blow-hole defect rejection rate is reduced. The target achieved is 0.94%.

Table 4: Cost benefit analysis 6.CONCLUSION

The main objective of the project work is to reduce the

Blow-hole defect rate in Cylinder block manufacturing thus the defect rate reduced drastically from 1.34% to 0.94%. The profitability for the foundry was increased directly by over coming the Rejection rate of Blow-hole.

7.REFERENCES

  1. Praevadee KaewkongKha, Somkiat Tangjitsitcharoen – IOSR Journal of engineering.

  2. Surjit Kumar Gandhi, Anish Sachdeva and Ajay Gupta Reduction of rejection of cylinder blocks in a casting unit: A six sigma DMAIC perspective. Journal of project management.

  3. Yogesh S.Dhumal, S N Teli, Siddesh Lad Problem solving methodology by Quality control story.

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