QC Story : Noisy steering operation of the tractor
1
1.1
PROBLEM - Identification & Definition
Problem Selection : Subtank without proper coolant Filter head assembly gasket leakage of tractor . Pivot pin greasing not done in tractors with power steering. Paint depositon on draft and paint knob. Inversion of alternator belt in 841 XM and 843 XM. Noisy steering operation of the tractor. Brake check nut loose.
1.2
Project Title i.e. Problem Definition To eliminate the problem of inversion of alternator belt Present Level of Problem :- Every Month 2~3 vehicle on average Held up in HUT Target Taken : - Elimination of problem.
1.3
Organization a) Project Leader : Mr. Subhash Chandra
b) Project Members : Anshul Gupta Archit Garg Salil Jain c) Facilitator : 1.4 Duration of the Project a) Date of Commencement: 05.06.2012 Mr. Vinay Kumar
b) Expected date of closure: 03.07.2012 C) Actual date of closure : 1.5 03.07.2012
Brief Description of the Problem The belt coupling the alternator with the fan belt pulley used to get inverted when the tractors were tested after the assembly line. This led to monetary loss to the firm.
1.6
History of Problem
3.5 3 2.5 2 1.5 1 0.5 0
Average
No. of Faults
On an average 2-3 tractor reported for this defect every month. 1.9
One of the damaged belts
2
2.1
OBSERVATION Recognition of Features of the Problem
Observation on Tractor Failure condition: Observations after roller testing
The alternator is not getting powered. The belt has got inverted.
2.1
Observation of the Process
Engine received at plant from the Rudrapur plant.
The engines are stored in the store for some days as inventory.
Engine Sub-Assembly
Engine Assembly
Coupling Area
Paint Shop
Dismounting
After roller testing some of the tractors show inversion of alternator belts.
2.2
Observation of Symptoms: The inverted belts hinders power transmission to the alternator.
2.3
Observation of Variation
Total Production: 2966
Model Wise: 735 FE: 843XM: 2624 342 Defected: 0 (0.00%) Defected: 2 (0.58%)
Sales
735FE 843XM
Thus this is dependent on the model type. The problem is found to be prominent with the model 843XM
Shift Wise: Shift A: 1436 Shift B: 1430 Defected: 1(.06%) Defected: 1(.06%)
Shift Wise
A B
Since the variation is not very major it is also independent of shift
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3.1
Analysis : Discovery of root causes
Probable Causes Low quality belts Damage in paint shop Alternator misaligned during fitment Design flaw Belt was put inverted Belt was slack Slippage due to paint Misaligned radiator water pipe clamp
3.2
Cause And Effect Diagram
Machine
Belt was put inverted
Man
Alternator misaligned during fitment
Misaligned radiator water pipe clamp Inverted Alternator Belt
Low quality Belt Belt was slack Damage in Paint shop Design flaw
Slippage due to paint
Material
Method
3.3
Verification Of Causes
Sr.No
Probable Cause
Method of Testing
Observations
Inference
Low quality belt
Observing trends in failure.
The problem does not occur in a batch as should have been the case.
Invalid
Damage in paint shop
Observing trends in failure.
Again most of the tractors would have failed had this been the cause.
Invalid
Alternator misaligned during fitment
Analysis of repair procedure
The alternator wasnt realigned for repair.
Invalid
Design flaw
Observing no. of failures.
This would have led to much more failures.
Invalid
Belt was put inverted
Observing the assembly procedure.
The assembly comprises of various manual stations. Thus such a case wont sustain.
Invalid
Belt was slack
Analysis of tightening procedure.
The tightening is done entirely on manual basis without any equipment for standardization. Such a problem would have caused huge no. of failures.
Valid
Slippage due to paint
Observing no. of failures.
Invalid
Misaligned radiator water pipe clamp
Inspection on such a tractor.
The problem of belt inversion was not found.
Invalid
3.4
Root Causes: Final Root Causes which came out to be valid is Slack alternator belt.
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4.1
ACTION To eliminate each Root Cause
Why Why Analysis to get Counter Measures Root Cause Inversion of alternator belt Why? The belt was slack. Why? The operator does not use any equipment. Why? He has not been provided with any such equipment for the concerned tractors.
List of Root Causes, Remedies Developed & Date of Implementation of each remedy The operator should be provided some standardizing equipment like tension gauge, torque
wrench etc.
5
5.1
CHECK Confirmation of Effectiveness of actions
Return on Investment N/A
5.2
Intangible Benefits Completely eliminated problem Delivery on schedule and low H.U.T. .
5.3
Adverse Effects (If any) NO
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6.1 6.2
STANDARDIZATION
List of Documents changed Alternator belt tightening SOP. Training given to concerned people: 7
The concerned personnel were familiarised with the new standards. 7
7.1
CONCLUSION Lessons Learnt Structured way of problem solving technique is helpful in foolproof solutions Gemba analysis is helpful concept to eliminate the problem from root.
_____________________ Project Leader
_____________________ Accounts Officer
__________________ PU Leader / PGL
______________________ Business Excellence PU
Design Suggestion for torque wrench Such shape can be formed out of a metal plate and welded onto a torque wrench at suitable position and there after suitable value for tightening of the alternator belt shall be obtained by experiment. the position where the hook end of the torque wrench may placed is shown by the red mark.
This position is same as that currently been used to tighten the belt using the screw driver so there wont be any problem of leverage.
