mahindra and mahindra - swaraj tractor division - project semester presentation

End Semester Industrial Training ReportMahindra & Mahindra Limited – Swaraj Tractors Division

Project 1

Eliminate the rejection/wastage of the engine oil in engine assembly due to

mixing of water in all models of tractor

Project completed by the Department of Quality Engineering and Assurance

Step 1 : Identification and definition of the problem

Brief Description of the problemEngine oil is used in the engine for lubricating moving parts to reduce friction between them. While checking the correct level of oil in the sump with the help of dipstick during pre-dispatch inspection of the tractors, colour of the engine oil was found changed due to water mixing.

Engine oil dip-stick

Water Mixing in engine oil leads to

Water Mixing with the Engine oil leads to

Rejection of oil is a monetary loss to the company

1Wastage of man

hours in replacing defective oil

2Wastage of oil leads to

national loss and environment pollution

3

Engine paper oil filter swells and has to be

replaced

4Engine moving parts

get rusted

5Loss of lubricating properties of oil which may result even

in engine seizure

6

History of problem

Supplier/ month

Aug’08 Sept’08 Oct‘08 Nov’08 Dec’08 Jan’09 Feb’09 Mar’09

Swaraj Engines Limited

1 3 1 1 10 6 7 6

Kirloskar Oil Engines Limited

8 4 4 3 9 2 1 1

Step 2 : Observation

1.Observation of the process2.Observation of symptoms3.Observation of variation

Observation of the process

Observation of symptoms

A Number of Tractors were selected from the yard and observed. It was found :- • In certain cases oil level in oil sump is found high and water level in radiator low. • In other cases there is no rise in oil level.• In all the cases engine oil red colour turns whitish ( milky )


Air leakage test is done to find out any points of leakage in the equipment. In the present situation the air leakage test was performed on the engine assembly to find out and leakage point from where water was supposedly getting mixed with the engine oil in the sump.

After the test was performed, following results were observed

•Air leakage observed from breather pipe joint in three cases –2 KOEL engines & 1 SEL engines.•Air leakage observed oil filler cape in one case - SEL•Air leakage observed from dipstick one case – ASSEMBLY

Air Leakage test

Observation of variation

52%48%

Supplier wise contribution in prob-lem

KOEL SEL

Step 3: Analysis

1.Possible causes2.Testing of probable causes

Possible causes

Testing of Probable causes

Sr.no.

Probable causes

Testing and observations Conclusion

1 Breather Pipe not fully inserted in hole

Besides observation on defective tractors, for this defect ,100 engine assemblies were visually inspected in plant and were found OK

Hypothesis invalid.

2 Breather pipe not seated or eccentric.

Visually inspected. No case found. Hypothesis invalid.

3 Excessive clearance between hole in Filler Body & pipe Outer Diameter.

Failed in Air & Water leakage test HypothesisValid.


4 Gap between bush Outer Diameter and hole in Oil Filler Body

Observation on 5 defective engines 26.945, 26.952, 26.958, 26.948 & 26.937mm. In addition to above Bush Outer Diameter checked with micrometer at SEL for 25 pieces. All pieces in between 26.93/26.958mm. Hence found OK.

Hypothesis invalid.

I) Bush Outer Diameter Under Sized

ii) Oil Filler Body hole U/S

Specification: Hole size 27+.033/+0 Bore Inner Diameter checked with plug gauge for 5 Defective engines and 25 engines from the latest supply of engines. All were found OK with plug gauge.

Hypothesis invalid.

Testing of Probable causes5 Sealant

application not OK

Failed in air & water leakage test. Air leakage test was conducted at 2kg/ cm2 pressure on five defective engines. Air leakage was observed in 3 engines at this point. Then possibility of water leakage was checked by pouring water as shown in photograph. Leaking water can be seen inside.

In one such opened up case sealant application was there but seemed to be inadequate.

Proper sealant was applied in this case and test was re-conducted. In this case no air or water leakage was found. Hence the reason is established.

When checked at SEL, application method was not mentioned in SOP.

Hypothesis valid.

Testing of Hypothesis

6 Sealant not applied

While analyzing defective tractors & 50 other cases at SEL, it was found that although the sealant application was done, but sealant was not applied appropriately & the phenomenon was listed in point no. 5.

Hypothesis invalid.

7 Oil filler cap assembly not tightened

Observation on defective cases & randomly audited 50 cases in two shifts in plant no case was found where the cap was not fully tightened.

Hypothesis invalid.


8 Rubber plug sealing not effective Out of 5 engines, water leakage was observed in one engine because of this fault.

i ) Rubber Plug eccentric and not perpendicular w.r.t cap

100 pieces were checked with gauge at the supplier end and 10 pieces were found defective as nut welding fixture was not there.

Hypothesis valid

ii) Rubber Plug material not as per requirement

Required material : Nit rile rubber

Rubber material of failed parts were checked and found as per specifications.

Hypothesis invalid

iii) Rubber Plug head Outer Diameter less by design

50 Cases were checked for leakage. Seepage was observed in 2 cases.

Hypothesis valid


9 Oil filler cap assembly Design inadequate.

I)Steel washer ineffective

Leakage observed in1 out of 5 cases when water was poured at this point.

There was metal to metal contact due to steel washer, As the hand tightening could not compress the steel washer required enough to provide effective sealing. When steel washer was replaced with “O” ring , no leakage was observed.

Hypothesis valid.

10 Filler body Gap between bush Outer Diameter & hole

i )Bore Over Sized

Specified bore size: 50.8+0.25/*0.00 mm

Checked with Vernier for failed cases & 25 new cases. It varied from 50.81 to 51.02 mm which was within limits.

Hypothesis invalid.

11 Dipstick not fully seated.

Checked visually. No case was found among defective and 100 other cases observed.

Hypothesis invalid.


12 Dipstick “O” ring sealing not effective.

I)“O” Ring size & thickness not OK Specification: Diameter 5.0 mm, Thickness 2.0 +/- .08

Observation on failed engine.

Hypothesis invalid.

ii) Groove diameter under sized Specification Dia. - 4.99 /5.1 mm, Thickness- 1.98/ 2.04 mm

Found OK.

Actual : OK with Plug gauge

No case was found in 100 cases Checked.

Hypothesis invalid.

iii) Hole diameter over sized in Crank Case

Specification : 5.3mm + 0.1 with plug gauge

Actual : OK with Plug gauge

No case found in 100 cases checked

Specification: Dia. 9.0±0.03

Hypothesis invalid.


13 Dipstick design not adequate.

Dipstick looses in 10 out of 100 Cases. Water seepage was also observed .Thus Design needs improvement. As per given tolerances on hole size,

Maximum hole diameter. = 9.03mm

Min. diameter over “O” ring after fitment in groove =9.04mm

So sealing compression on "O" ring is 10 micron only.

Minor flash / oval-ness or eccentricity of “O” ring groove diameter in plastic mold made the ring free (without compression) on one side. Thus making way for water.

Besides Dipstick Head design being flat is not helpful in preventing the water reach “O” ring.

Hypothesis valid.


14 Flash over plastic molding not dressed.

I)Die not reworked

Water seepage was observed due to flash over plastic

Mold. It causes the dipstick tilt to one side thus creating gap on one side of the “O” ring

In one case of engine oil contamination by water, Dipstick had conspicuous flash on parting line. This dipstick was tried on loose Crank Case (as shown in photograph) by pouring water.

Water seen dripping across “O” ring

Supplier has no Die rework schedule.

Again all these defective dipsticks were refitted after proper dressing and no leakage were observed. Hence the problem is established.

Hypothesis valid

Dipstick

Root causes identified

1. Sealant not applied properly between Breather Pipe bush Outer Diameter and Oil Filler body Inner Diameter

2. Rubber Plug (Bellow) eccentric and not perpendicular w.r.t. cap. (Oil filler cap).

3. Rubber Plug head Diameter less as per Design.4. Steel Washer ineffective in Oil Filler Cap Assy.5. Dipstick design not adequate.6. Flash over Plastic Outer Diameter due to plastic

molding (Dipstick).

Actions taken to eliminate root causes

Sr.No. Root Cause Remedial Action1 Sealant not applied properly (breather pipe bush

)SOP provided and operators were educated as per SOP at the suppliers end

2 Rubber plug eccentric and not perpendicular w.r.t. cap (oil filler cap)

New welding fixture designed ( J68080 ). Alternate design for nut welding provided (vides drawing no. V085633/1)

3 Rubber plug head diameter less Diameter changed from 61mm to 63.5 mm

4 Steel washer ineffective in oil filter cap assembly Design changed1 ) Steel washer replaced with “O” ring

5 Dipstick design inadequate Dipstick head made cup shaped“O” ring thickness increased from 2mm to 2.15 mm

6 Flash over plastic molding (dipstick) Dye re-work schedule made (50,000 cycles )

Project 2

Eliminate Rejection / Wastage of Diesel due to leakage from fuel cock Assembly

Project completed by the Department of Quality Engineering and Assurance

Step 1 : Identification and definition of the problem

Brief Description of the problemFuel Cock Assembly is connected between the Fuel Tank Assembly and to the Water Separator through Fuel Pipe, Fuel Cock Assembly is used in the diesel circuit to stop and open the Diesel flow to the feed pump by gravity. Fuel cock Assembly is connected to the Fuel Tank with a sealing Rubber ring between Fuel Cock and Fuel Tank. A Fuel Pipe is used to carry the Diesel to Water Separator with a banjo bolt and two metallic sealing washers (Aluminum)

The Diesel Leakage through Fuel Cock Assembly leads to

Fuel cock assembly

The Diesel Leakage through Fuel Cock Assembly leads to

Loss of Diesel, which is

monitory loss to the customer

and to company

1Entire area below

the Fuel tank Assembly becomes oily which is major

irritation

2Leakage accumulate on the parts showy

shabby looks and eye sore to the customer

3

If the complaint is not attended immediately,

this may lead to engine stop

4It also leads to delay of the finish goods

dispatch.

5Environment of safety

6

History of problem

May-08

June-08

July-08

August-

08

Septem

ber-08

October-

08

November-

08

December-

08

January

-09

Febru

ary-09

0

2000

4000

6000

8000

10000

12000

PPM

Step 2 : Observation

1.Observation of the process2.Observation of symptoms3.Observation of variation

Observation of the process

Brief Description

Fuel cock assembly is used in fuel line of the tractor assembly. Its main function is to cut-off or release the fuel to the fuel line. Fuel cock assembly is consists of main parts like body, knob, and rubber sealing ring. Fuel cock is fitted to the main tank with rubber ring . Fuel pipe is fitted with fuel cock with banzo and aluminum washer.

Upper leakage point AL washer

Bottom leakage point AL washer

Diesel Off / On Knob leakage point

Fuel Cock Assy

Banjo bolt

Brief Description

Interface of Fuel Cock & Fuel Tank Assembly

Fixed Torque wrench


1. Heavy leakage of diesel on tractors in rework.2. P.D.I audit (leakage)3. IQS score

1. I5 cases of Diesel leakage from PDI area & 5 cases from tractor re-work area were studied. In 15 Cases leakage was observed from bottom face of banjo bolt ,in 4 case mountings with tank & 1 case from Fuel cock knob.

2. Leakage from the bottom face of the banjo bolts 3. This defect observed in all models of tractors.4. Torque value of 18 lbsft for banjo bolt tightening was observed under torque with dial type

torque wrench. In other 4 cases leakage found from interface of Fuel cock Assembly & Fuel Tank Assembly. In one case leakage was observed from Fuel Cock knob.

Step 3: Analysis

1.Possible causes2.Testing of probable causes

Possible causes


1 Banjo bolt under torque On 15 defective tractors we have checked the leakage tractor testing of banjo bolt found under torque on 15 tractors. Specified = 18 lbsft Observed =12 -14 lbsft

Hypothesis valid.

2Aluminum washer face dented

In all 15 defective tractor AL washer face checked all were ok

Hypothesis Invalid.


3 Al washer High hardness At random 10 Pc of Al washers checked for hardness. Given hardness = 40-42HB Observed = 40-41HB

Hypothesis Invalid

4 Fuel cock M16x2 face not flat

All fuel cock was checked for flatness with the help of calibrated square gauge. All pieces, were qualified the gauge.

Hypothesis Invalid

5 Banjo bolt Ø 14 not concentric with M14x1.5

Five banjo bolts removed from the defective tractor and checked with concentric gauge (J61405A). All were qualified the gauge. ┴ =.05 max.

Hypothesis invalid.


6 Rubber sealing ring not seated in fuel tank groove

In four out of 20 defective tractors when dismantled rubber ring found damage all sealing ring replaced with new ring fitted with tractor not leakage found.

Hypothesis valid


7 Sealing ring (P395208) diameter undersize & hardness variation

15 Sealing ring were checked for diameter & shore hardness. Diameter-ØO/D Specified = 16.5±.10

Ø O/D Observed = 16.5±.10

Thickness = 1.78±..076

Shore hardness - Specified = 65±5

Observed= 63-66

Hypothesis invalid.

8 Fuel Tank groove depth excess & M14x1.5 thread not ┴ or to the groove.

Five defective fuel tank were checked for depth & ┴ 0.1 or all were qualified in the gauge No. J61408.Squareness checking gauge numberAlso 100 pieces at random were also checked on line with gauge all were qualified.

Hypothesis invalid.

9 Fuel pipe butting not parallel to each other

All defective pipes checked for parallelism with micro meter.All reading Specified = 0.1mmObserved = 0.09mm

Hypothesis invalid.


10 Fuel pipe butting not parallel to each other

In one case out of 20 , leakage observed from Fuel Cock knob when tested with air pressure at 1.5 kg /cm2

Hypothesis Valid

Root causes identified

1. Banjo bolt found under torque. 2. Rubber sealing not seated in groove 3. Fuel leakage from fuel cock knob

Actions taken to eliminate root causes

Sr. no.12

3

Root CauseBanjo bolt under torqueRubber sealing ring not seated in

fuel tank groove. Fuel leakage from fuel cock knob

Remedial ActionStandard operation process (SOP) made and worker educated for adhering to this. Standard operation process (SOP) made and worker educated for adhering to this.System designed

Thank you

mahindra and mahindra - swaraj tractor division - project semester presentation

Documents