elimination of rejec tion in injector manufacturing ...€¦ · c. arun, r. arunkumar, s....

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International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 3, March 2017, pp. 331–343 Article ID: IJMET_08_03_037 Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=3 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication Scopus Indexed

ELIMINATION OF REJECTION IN INJECTOR MANUFACTURING PROCESS BY USING

HYDRAULIC FIXTURE P. Yogesh

Assistant Professor, Department of Mechanical Engineering, Vel Tech (RS Trust), Chennai, Tamilnadu, India

C. Arun, R. Arunkumar, S. Muruganantham, P. Abinesh Final Year Student, Department of Mechanical Engineering, Vel Tech (RS Trust),

Chennai, Tamilnadu, India

ABSTRACT The aim of this project is to eliminate the rejection in injector manufacturing

process in CNC machine in injector Body. Average rejection quantity per month in the industry is around 500nos (0.6%) out

of 80,000nos production per month in injector body and we have analysis the problem and taken improvement activities to eliminate the rejection and to improve production Nozzle holder body is a one of the major part in injector assembly variation in the dimension NHB leads to rework or rejection in the production of nozzle holder body (NHB). The main objective or aim of the project is to eliminate the rejection and rework in the production of nozzle holder body using hydraulic fixture.

The purpose of the this project is to minimize the cost and effort involved by eliminating the rejection, rework, loading damages, operator fatigue and also by increasing the production rate using an effective and automated hydraulic fixture system

Key words: injector, productivity CNC machine, hydraulic fixture. Cite this Article: P. Yogesh, C. Arun, R. Arunkumar, S. Muruganantham and P. Abinesh, Elimination of Rejection in Injector Manufacturing Process by using Hydraulic Fixture. International Journal of Mechanical Engineering and Technology, 8(3), 2017, pp. 331–343. http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=3

1. INTRODUCTION

1.1. Fuel Injectors Fuel injectors are small electro-mechanical devices that are used to spray fuel into the intake manifold directly in front of the intake valve. The injector has a final high micron filter in the top inlet side and small hypodermic-sized holes on the bottom for the atomizing of fuel.

Elimination of Rejection in Injector Manufacturing Process by using Hydraulic Fixture


Fuel acts as a lubricating agent for the injector. Water in the fuel is extremely damaging to the injectors due to the fact that it displaces the lubricating properties of the fuel .Injectors open and close at the same rpm as the engine. This equates to more than 138,000 times an hour.

Figure 1 Fuel Injector Fuel injectors are subject to carbon and dirt introduced by a bad air cleaner element. The

type of fuel used and the grade as well as the additives directly effect the life expectancy of the injectors.

1.2. Problem Description Due to insufficient resting area of the product and improper loading of the work piece which move forward from the reference point while machining, which is due to shear force acting on the material by using shot end mill. Due to the action of shear force acting on the working material this lead to dimension variation in material and occur more rejection.

2. MATERIAL AND METHOD

2.1. Quality In manufacturing, a measure of excellence or a state of being free from defects, deficiencies and significant variations. It is brought about by strict and consistent commitment to certain standards that achieve uniformity of a product in order to satisfy specific customer or user requirements.ISO 8402-1986 standard defines quality as "the totality end characteristics of a product or service that bears its ability to satisfy stated or implied needs

2.2. Seven Basic Tool of Quality The Seven Basic Tools of Quality is a designation given to a fixed set of graphical techniques identified as being most helpful in troubleshooting issues related to quality.

They are called basic because they are suitable for people with little formal training in statistics and because they can be used to solve the vast majority of quality-related issues.

The Seven Basic Tools of Quality includes: Check sheet

Stratification

Histogram

Pareto chart

Ishikawa (fishbone) diagram

Scatter diagram

Control chart

P. Yogesh, C. Arun, R. Arunkumar, S. Muruganantham and P. Abinesh


2.2.1. Root Cause Analysis Based on the root cause analysis (fish bone diagram).The issue found in the job moment along axially while machining. The basic approach when a job moves down while machining is to provide an extra support in the opposite direction of its movement. But since the cradle plate rotates 180 degree we cannot implement a fixed block or a support.

We need to implement a fixture that should be fixed out the radius of cradle plate and also it should have some kinds of extension so that it support the job from the bottom after the cradle plate turn about 180 degree Prime causes validation

Figure 2 Root cause of the problem by using fishbone diagram

2.2.2. Possible Cause The possible cause for the depth variation and checks has been tabulated. The prime cause or the significant cause for the depth variation is identified in table 1

Table 1 Possible Cause

CATEGORY POSSIBLE CAUSES VALIDATION RESULT

Unskilled Checked

Trained Insignificant

Operator

Operator

MAN

Wrong Checked Insignificant

Loading Loading

Play in Checked Ok Insignificant

Chuck

MACHINE

Improper Checked Ok Insignificant

Maintenance

Lack in Calibration

Report Insignificant

MEASURE Calibration

Verified

-MENT

Improper Gauge verified Insignificant

Gauge Ok

Hydraulic No Variation Insignificant

Pressure

Component Additional

support Significant

CLAMPING sliding

needed



Metal chips

inholding Checked Ok Insignificant

area

Defective Report Insignificant

Input RM Verified Ok

MATERIAL RM

Dimensional Checked Ok Insignificant

Variation

COOLANT Coolant Checked Insignificant

On/Off

2.2.3. Control Chart

Figure 3 Control Chart This control chart shows the variations of the manufacturing by using the fresh tools. By

using the fresh tools this chart shows that the cycle is in safe zone and within the limits.

Figure 4 Control Chart This control chart shows the variations of the manufacturing by using 1st reground tool.

By using this tool this chart shows that the cycle is in medium safe zone and partially in limits.



Figure 5 Control Chart By using second time reground tools it shows that the manufacturing limit is in danger

zone and it crossed the limits This is due to the shear stress which acted upon the work piece.

Figure 6 Machine wise rejection trend-jan-2106 Based on cycle time and productivity hours the number of component targeted per day is

197 nos. Out of 197 an average of 25 to 28 components gets rejected. The main cause for the rejection is due to the depth variation during solenoid hole drilling

operation The depth of the solenoid hole is 29.4mm with the tolerance of 40microns.since the tolerance limit is more critical, a small variation in holding the NHB while machining causes depth variation. Achieving the required dimension with the existing equipment and process becomes undesirable



Figure 7 Pato analyse The depth of the solenoid hole is 29.4mm with the tolerance of 40 microns. Since the

tolerance limit is more critical, a small variation in holding the NHB while machining causes depth variation. Achieving the required dimension with the existing equipment and process becomes undesirable

2.3. Calculation of Rejection Rate The productivity hours and non-productivity hours in a shift is shown in table 2 and calculate for the rejection rate is as follows.

Table 2 Productivity Hours

Shift Timing Non Productivity Hours Starting time 7:45 Tea break 15 Mins

Ending time 4:15 Lunch break 45 Mins Total Hrs 8:30 Tea break 15 Mins Total shift 510

Nonproductive time 75

Mins

time Mins Total productivity time per shift = Total shift time- Non productivity time

= 510 – 75 = 435 Mins No of component targeted per shift = Total productivity time per shift/ cycle time = 435 / 2.2(Mins)

=197 Nos(Approx = 200) Actual no of component produced = 190 (+/- 3) No’s. No of Rejections per shift = 25 to 28 No’s Total Rejection Rate = 28 / 190 = 14.7%



2.4. Possible Solution As stated in the above prime cause validation we found that the issue is with the clamping which lead to movement of NHB during drilling operation. The solution

We concluded is shown below figure 8 Increasing clamping area is not possible since the job is premachined so the total clamping area is limited to 35 mm. So applying back pressure is the only way to fix this issue. In Applying back pressure can be done by several methods. It can be mechanical or hydraulic or pneumatic system.

Figure 8 Possible Solution Since movement of mechanical parts and pneumatic system are noisy, heavy construction,

automation complexities, poor repeatability, speed, not reliable, difficulty in control and space constraints are in the mechanical system and pneumatic system is not selected. The hydraulic system which the pressure can be varied by adjusting the pressure regulator, less noisy, wide range of speed, load controls and deliver high pressure with more precise movement the hydraulic system is selected in this project to solve this issue.

3. EXPERIMENTAL SETUP AND PROCEDURE

3.1. Hydraulic Fixture Circuit The hydraulic fixture circuit and BOM are shown in the figure 9

Figure 9 Hydraulic fixture circuit



Table 3 Part Description

Figure 10 Hydraulic fixture design

Figure 11 Hydraulic fixture design view



Figure 12 Hydraulic fixture design measurement

Figure 13 Working machine

Figure 14 Hydraulic chuck with unloaded work piece



Figure 15 Hydraulic chuck with loaded work piece This fig shows the top view of fixture after 180 degree of rotation. The component is

rigidly clamped in between the hydraulic cylinder and stopper. This is ready for 5 axis machining

Figure 16 Hydraulic fixture front view This fig shows the fabricated view of the hydraulic fixture which is used to hold the work

piece when its from 0 degree to 180 degree

3.2. Hydraulic Fixture Setup This fig shows that the hydraulic fixture which is fabricated is in 0 degree angle and fitted with the power pack assembly and which is ready for machining

Figure 17 Hydraulic fixture which turns at 180 degree angle



3.3. Fabrication of Power Pack

Figure 18 Fabrication of Power Pack

3.4. Power Pack Assemble

Figure 19 Power Pack Assembly The fabrication is nothing but the skeleton of power pack shown in figure 18. The pump,

motor, pressure regulator, strainer, pressure relief valve, pressure gauge etc are mounted on the skeleton of the powerpack. The assembled power pack is shown in the fig 19. The motor is driven by the electrical energy. The motor drives the pump through coupling and create a pressure difference in the system. Due to the pressure difference the pump delivers the oil from tank to pressure control valve at high pressure. The pressure regulator is set to the required delivery pressure by adjusting the regulator screw. The excess pressure developed in the power pack is returned to the tank through a return circuit. The exact required pressure is sent to the four way direction control v



4. RESULTS AND DISCUSSIONS Figure After implementation of fixture

Figure 20 After implementation of fixture This chart shows that after the implementation of the hydraulic fixture and by using the

second time reground tool the product which are produced are in safer zone and within the limits.

4.1. Histogram Figure after implementation trail taken with 2^nd red round tool

Figure 21 After implementation

4.2. Rejection Rate Recalculation No of component Tested = 50 Nos. No of Rejections = Nil 0 Nos. Total Rejection Rate = 0/ 50 = 0 %

Therefore by rejection rate because of the depth variation becomes zero percentage after implementation of the project



5. CONCLUSION The purpose of this project is to reduce the rejection and rework in the production of nozzle holder body. According to the trial experiments and data observed the deviation in the dimension of the depth is reduced. The rework and rejection rate in the production of the nozzle holder body is reduced. Because of this hydraulic fixture implementation can be achieved the required dimension within the tolerance. The rejection rate is eliminated from 15% to 0%. It also avoids rework time and wastage of Pre-machining cost. This fixture also enhances the production rate.

In addition to all the above statement this fixture reduces the operator fatigue and a High degree of dimensional accuracy is achieved with high quality & customer satisfaction. Hereby declare that the elimination of rejection in the production of Nozzle holder body using the hydraulic fixture is successfully implemented

5.1. Future Enhancement The same fixture can be re modified for the other two types of the injector body production. We can use the same power pack for two machines by adjusting the pressure regulator. Since the pressure developed in the power pack is 100 bar it has the capability to accommodate one more fixture which is fixed in another machine also. If the same power pack can be used then there will be a cost saving to the company since the major cost involved can be minimized for the future extension

REFERENCES

[1] Prof. Vasim A. Shaikh1, Prof. Prashant B. Kuyate2, Punam A. Bhamare3, Vishal K. Sapkal4, Aishwarya V.Shinde5, “ Hydralic Press Machine For Handle And Trigger Assembly Of CP Breakers With Fixture ” International Conference On Emerging Trends in Engineering and Management Research, 23 March 2016 ISBN: 978-81-932074-7-5.

[2] S.R.Vijayakumar1, Dr.S.Gajendran2, “Improvement of Overall Equipment Effectiveness (OEE) in Plastic Injection Moulding Industry” IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684, p-ISSN: 2320-334X PP 32-45.

[3] Abhijeet Swami1, Prof. G.E. Kondhalkar2, “Design, Development and Analysis of Hydraulic Fixture for machining Engine cylinder block on VMC” International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 p-ISSN: 2395-0072.

[4] Komal Barge1, Smita Bhise2, “Design & Development of Hydraulic Fixture for VMC” International Journal for Research in Applied Science & Engineering Technology (IJRASET) Volume 3 Issue IV, April 2015 ISSN: 2321-9653.

[5] S.R.Vijayakumar1, S.Gajendran2, “Improvement of Overall Equipment Effectiveness (OEE) In Injection Moulding Process Industry” IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e- ISSN: 2278-1684, p-ISSN: 2320–334X PP 47-60.

[6] Shailesh S.Pachbhai1 , Laukik P.Raut2, “A Review on Design of Fixtures” International Journal of Engineering Research and General Science Volume 2, Issue 2, Feb-Mar 2014 ISSN 2091-2730.

[7] Molham Chikhalsouk, Hussni F. Al - Hajjar, Rama B. Bhat and Yasser Mohamed El-Okda. Empirical Investigation on The Influence of Bent Axial Piston Pumps’ Control Systems’ Gains on Hydraulic Pipes Stability, International Journal of Mechanical Engineering and Technology, 6(10), 2015, pp. 217-231

[8] Aakash M Bodh and Prof. G.H. Waghmare, Study, Design and Improvement of Pumping System Efficiency of Hydraulic Pneumatic Reciprocating Pump. International Journal of Mechanical Engineering and Technology, 7(5), 2016, pp. 127–132.

elimination of rejec tion in injector manufacturing ...€¦ · c. arun, r. arunkumar, s....

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