1. Minimization of Leakage in
Outer Tube
Model: ALTO
7/6/2011
Gabriel India Limited, Khandsa
Shantanu Krishna
2. ACKNOWLEDGEMENT
I express gratitude and am thankful to all the people at Gabriel India Limited who helped make
my training a success. I feel I have been a part of the Gabriel family if only for a short time and
shared the work culture which teaches strict self discipline and a goal oriented approach. I owe
my success to many people who guided in time of need and shared with me their valuable time
so that I could develop.
I would like to thank:
Mr. Dheeraj Khanna
For assigning this project and constantly guiding me. He also provided me necessary
information regarding Gabriel operations standards, goals and targets.
Mr. Amit Kumar Sharma
For helping me validate all the incoming products like the end cap, outer tube etc.
Mr. Sandeep Kumar
For constantly helping me in minimizing the leakage problem and process analysis.
3. Index
Section I
1. Anand Automotive Systems
2. Gabriel India Limited
3. Gabriel India Limited Khandsa
4. Introduction to Shockers
5. Process of Manufacturing a Strut
Piston Rod Operations
Outer tube machining
Inner tube
Damper Assembly
Final Assembly
Section II
Minimizing Leakage in Outer Tube- ALTO CD
1. Problem Identification
2. Measurement & collection of data
3. Relationship between rate of nozzle cleaning & rejection.
4. Analyzing & identifying the root cause
5. Process improvement
6. Result after improvement.
4. ANAND AUTOMOTIVE SYSTEMS
Anand Automotive Systems is a leading manufacturer of automotive components and systems in
India, supplying to virtually every vehicle and engine manufacturer in India. With the largest
range of automotive components
Vision – To Become the Leading Automotive Systems Group In India GFGF
Mr. Deep C Anand, Chairman, Anand Automotive Limited, in 1961 launched the group with the
establishment of Gabriel India, the Group’s flagship Company in Mumbai for the manufacturing
of Shock Absorbers.
With the vision of becoming a leading automotive systems supplier in India, today the group
comprises of 19 companies in 11 locations with 38 plants and employing more than 7500
employees.
The Group benchmarks its products with world-class manufacturers.It believes in the philosophy
of continuous improvement through innovations keeping in mind the customer’s expectations.
Anand Philosophy:
World-class Manufacturing
Growth Ahead of Market
People Orientation
Return on Investment
Continuous Improvement
Anand Beliefs:
Develop Corporate Competence to act Globally
Aspire and Dare to Innovate
Attain Leadership in Technology
Achieve Excellence through Entrepreneurship
Bridge the Gap between Precept & Practice
5. Anand’s Way of Working:
We drive Anand as a unified corporate entity
We aspire to be a world-class organization
We encourage organizational transparency
We value integrity
We encourage innovation
We nurture talent
We support continuous education
We build trust and empower people
We practice open and honest communication
We recognize and reward success
We are an equal opportunity employer
We accept social responsibility
Anand Group is a unified corporate entity manufacturing ancillaries for all the segments of
transportation. The group comprises of various companies which are in strategic alliances either
through a joint venture or a technical license.
Some of the group companies are:
COMPANY PRODUCT
Gabriel India Shock Absorbers, Struts & Front Forks
MAHLE Filter
Systems India
Automotive & Industrial Filters, Plastic Intake
Manifold & Cylinder Head Cover
Anfilco India Industrial Filters
Henkel Teroson India Adhesives, Sealants & Coolants
Chang Yun India Synchronizer Rings
Behr India Limited
Air conditioning systems, Cooling
Module System,
Radiator
Charge Air Cooler
Condenser
Mando India Limited Hydraulic Brakes, Shock Absorbers
Valeo Friction
Materials India
Limited
Clutch Facings
Anand Engine
Components
Engine Bearings, Bushes, Solid
Flanges & Washers
Perfect Circle India
Limited
Piston rings, Castings & Plates
Victor Gaskets India
Limited
Non-asbestos gaskets, Fluorelstomer
coatings, Heat shields
Spicer India Limited Axles, Driveshafts, Driveline
6. Haldex India Limited Air Brake Components
Emcon Technologies
India Private Limited
Exhaust Systems
Takata India Private
Limited
Seat belts, Air bags & Steering wheels
Camfil FARR Air Filtration India Industrial Filters
Federal – Mogul
Engine Bearings India
Limited
Engine bearings, Bushes, Solid Flanges &
Thrust washers
Degrémont Water & Waste-water Technologies
SNS Foundation Non- Profitable Organization
Hospitality
GABRIEL INDIA LIMITED
VISION: To gain respect of all our customers and stakeholders by achieving & sustaining the
status of preferred supplier of suspension product for passenger cars through benchmarked
performance on Quality, Delivery, Cost and Speed of response.
Established in 1961 in Mulund, Mumbai, Gabriel today makes the nation’s widest range of Ride
Control products like dampers, Shox, Struts and Front Forks. The company has six plants in the
country catering to almost every Automobile manufacturer. The six plants are located in Hosur,
Nashik, Mumbai, Pune, Gurgaon and Dewas. The company has collaboration with Kayaba,
SOQI (Japan), APA Kayaba (Spain), Arvin (USA) and Federal Mogul (USA).
The various plants of the company have ISO-141001, OHSAS, TS 16949 and other Quality
system certifications. The company is also aggressively pursuing continual improvement
initiatives like TPM (Total Productive Maintenance), 100PP and TQM (Total Quality
Management). The company has received a number of appreciation certificates both from the
customers and Government on the various initiatives. The company is progressively becoming
an aftermarket supplier.
7. Gabriel’s List of Customers Includes:
PASSENGER
VEHICLES
COMMERCIAL VEHICLES
&
OTHERS
MARUTI SUZUKI ASHOK LEYLAND
MITSUBISHI TATA
GENERAL MOTORS SWARAJ MAZDA
HINDUSTAN MOTORS INDIAN RAILWAYS
ASHOK LEYLAND EICHER
FORD HYUNDAI
TOYOTO MAHINDRA
Location of Plants
8. GABRIEL INDIA LIMITED – KHANDSA (GURGAON)
VISION - “To be Leading Global Original Equipment Supplier of Ride Control for Four wheeler
& Two-Wheeler and Automobile Application.”
MISSION - “The purpose of GIL, Gurgaon is to be a leader in serving the needs of Northern
India OEMs, After Market and Export customers by providing products and services of superior
quality at most competitive prices.”
This is brand new Greenfield facility in a most strategic location of Indian Auto giants at
Khandsa, with a comprehensive & Integrated Production System [IPS] for manufacture of gas
charged shock absorbers.
9. Plant Profile
AREA 12150 mt. sq. (3 acres)
TOTAL INVESTMENT PLAN INR 800 MILLION
COMMENCEMENT OF
PRODUCTION
APRIL 2008
CUSTOMER/S MARUTI SUZUKI & AFTER MARKET
QUALITY CERTIFICATE ISO / TS – 16949 : 2009
TECHNOLOGY EMPLOYED KAYABA (JAPAN) & GRC
Introduction to Shockers
Unless a dampening structure is present, a car spring will extend and release the energy it
absorbs from a bump at an uncontrolled rate. The spring will continue to bounce at its natural
frequency until all of the energy originally put into it is used up. A suspension built on springs
alone would make for an extremely bouncy ride and, depending on the terrain, an uncontrollable
car. Enter the shock absorber, or snubbed, a device that controls unwanted spring motion through
a process known as dampening. Shock absorbers slow down and reduce the magnitude of
vibratory motions by turning the kinetic energy of suspension movement into heat energy that
can be dissipated through hydraulic fluid. To understand how this works, it's best to look inside a
shock absorber to see its structure and function.
10. A shock absorber is basically an oil pump placed between the frame of the car and the wheels.
The upper mount of the shock connects to the frame (i.e., the sprung weight), while the lower
mount connects to the axle, near the wheel (i.e., the unsprung weight). In a twin-tube design, one
of the most common types of shock absorbers, the upper mount is connected to a piston rod,
which in turn is connected to a piston, which in turn sits in a tube filled with hydraulic fluid. The
inner tube is known as the pressure tube, and the outer tube is known as the reserve tube. The
reserve tube stores excess hydraulic fluid.
When the car wheel encounters a bump in the road and causes the spring to coil and uncoil, the
energy of the spring is transferred to the shock absorber through the upper mount, down through
the piston rod and into the piston. Orifices perforate the piston and allow fluid to leak through as
the piston moves up and down in the pressure tube. Because the orifices are relatively tiny, only
a small amount of fluid, under great pressure, passes through. This slows down the piston, which
in turn slows down the spring.
Shock absorbers work in two cycles -- the compression cycle and the extension cycle. The
compression cycle occurs as the piston moves downward, compressing the hydraulic fluid in the
chamber below the piston. The extension cycle occurs as the piston moves toward the top of the
pressure tube, compressing the fluid in the chamber above the piston. A typical car or light truck
will have more resistance during its extension cycle than its compression cycle. With that in
mind, the compression cycle controls the motion of the vehicle's unsprung weight, while
extension controls the heavier, sprung weight.
All modern shock absorbers are velocity-sensitive -- the faster the suspension moves, the more
resistance the shock absorber provides. This enables shocks to adjust to road conditions and to
control all of the unwanted motions that can occur in a moving vehicle, including bounce, sway,
brake dive and acceleration squat.
11. Advantages of Shockers
1. Improve ride handling
2. Prevent spring back
3. Reduce tyre wear
4. Save fuel cost
5. Extend vehicle life
Functions of Shock Absorbers:
1. The shock absorber reduces vehicle vibrations to improve the ride comfortableness and to
protect loads and it reduces dynamic strains at various portions in the vehicle body to expand
the lifetime, and it improves road contact to improve steering stability, reducing impacts in
adverse road conditions.
2. The shock absorber acts as a device for restricting vibrations and this force is called
damping force. The performance of shock absorber is obtained from the relation between the
operating speed and the damping force.
Various models of Shock Absorbers manufactured at GABRIEL INDIA are:
Model Name VEHICLE AT MARUTI INDIA
O2 EECO
YR9 WAGON R
YC5 A STAR
CAR MARUTI 800
ALTO ALTO
MINOR OMNI
YY4 SX4
12. The Process Flow- Manufacturing of a strut
Rod Cell Operations
Raw Bright Bars
The first section of the process is the rod cell operations where the piston rod is prepared for the
strut. The piston rod at the beginning is a medium carbon steel rod of a specified cut length
which when undergoes operations various operations like hardening, grinding etc.
Hardening & Tempering
Hardening and Tempering Machine
The first step in the rod cell operations is hardening of the piston rod. The purpose of this process
is to increase the strength of the rod and alter the mechanical and physical properties of the rod,
to soften the rod and to remove the stresses. Hardening is a form of heat treatment in which a
metal part is heated by induction heating and then quenched. The quenched metal undergoes a
martensitic transformation, increasing the hardness and brittleness of the part. Induction
hardening is used to selectively harden areas of a part or assembly without affecting the
properties of the part as a whole.
13. The hardened piston rod is now tempered in a tempering machine. Tempering is a heat treatment
technique for metals, alloys and glass. In steels, tempering is done to "toughen" the metal by
transforming brittle martensite or bainite into a combination of ferrite and cementite. Tempering
is accomplished by a controlled reheating of the work piece to a temperature below its lower
critical temperature.
Hardened and Tempered Rods
Rough Grinding
Rough grinding (Surface grinding) is used to produce a smooth finish on flat surfaces. It is a
widely used abrasive machining process in which a spinning wheel covered in rough particles
(grinding wheel) cuts chips of metallic or non metallic substance from a work piece, making a
face of it flat or smooth.
Surface grinding is the most common of the grinding operations. It is a finishing process that
uses a rotating abrasive wheel to smooth the flat surface of metallic or nonmetallic materials to
give them a more refined look or to attain a desired surface for a functional purpose.
Rough Grinding Machine
14. Machining
CNC LMW
This process includes a number processes within itself. The term rod machining covers the
operations like facing, turning, threading etc. of the both ends. The purpose is to achieve
dimensions of piston rod according to the product requirement
Piston End Machining
Machined Piston Rods
The main purpose of this operation is to give the desired shape to the piston rod. The process is
carried out on CNC-Lathe. The mounting end is held in the chuck and other end ie. the piston
end is machined with the help of the the tools held in the turret. The operations carried out on the
rod are- facing, turning, taper turning etc.
Mounting End Machining
The purpose of the operation is same and the process is also carried out on a CNC lathe. The
mounting end is of greater length as compared to the piston end. The operations that are carried
out are facing, turning, taper turning, step turning etc.
15. Mounting End Threading
Thread Rolling Machine
The next step is to draw threads on the machined mounting end. The threads are drawn with the
help of two dyes of a specified size. We place the rod in between them and moving in opposite
directions they draw threads of the desired pitch.
Flat Milling
Flat Milling On Piston End
The threaded end of the piston rod is now milled and a portion of the mounting end is removed
making one end of ‘D’ cross section. This process is performed for preventing any slipping of
thread when the strut is mounted on a car.
16. Piston End Threading
Rods After Threading
This step is almost similar to the mounting end threading as threads are drawn on the piston end
in this case. The only difference is that the dyes are of differ in size from that of mounting end
threading.
Semi Finish & Finish Grinding
These are the last two stages of grinding.The machine consists of a table that traverses both
longitudinally and across the face of the wheel. The longitudinal feed is usually powered by
hydraulics, as may the cross feed, however any mixture of hand, electrical or hydraulic may be
used depending on the ultimate usage of the machine (ie: production, workshop, cost). The
purpose of grinding is still the same but it also improves the finishing of the rod. The amount of
material removed is much lesser in both these cases with finish grinding removing the least. ie.
approximately 20-40 microns.
Finish Grinder & Semi Finish Grinder
17. Chrome Plating
The purpose of this process is to achieve better life and better surface finish of piston rod. A
machine named Dynachrome, a highly sophisticated machine, is used to execute the process. The
chrome plating takes place immediately after pre-grinding. This eliminates storage periods
requiring temporary corrosion protection. In contrast to conventional systems, the
DynaChrome® system plates to final specifications. Grinding to size can be omitted from
mechanical post-processing - which substantially reduces chromium consumption by 15% and
energy consumption by 30%.This makes this a highly efficient process.
Dynachrome & Chrome Plated Rods
Polishing & Buffing
Polishing and buffing are finishing processes for smoothing a workpiece's surface using an
abrasive and a work wheel. Technically polishing refers to processes that use an abrasive that is
glued to the work wheel, while buffing uses a loose abrasive applied to the work wheel.
Polishing is a more aggressive process while buffing is less harsh, which leads to a smoother,
brighter finish. A common misconception is that a polished surface has a mirror bright finish,
however most mirror bright finishes are actually buffed.
Buffing Machine
18. Spot Welding
The spot welding process is used to weld a rod stopper to the piston rod. The rod is kept in the
centre of the four pneumatic pressure controlled welding arms of the machine with the rod
stopper placed at its proper position. The stopper is then spot welded at four points.
Spot Welding Machine & Piston Rod with Rod Stopper
Outer Tube Machining
The outer tube is a cylindrical tube open from both sides. The tube holds the entire assembly
together and within it. The machining of outer tube comprises of various processes like Drawing,
machining, crimping, etc.
Drawing
In this process the outer tube is placed in outer diameter drawing machine. This machine reduces
the diameter of the lower side of the outer tube by a few millimeters. The purpose of this process
is to make the lower side of the tube of the adequate size so that the knuckle bracket can be
easily fixed on to it.
Lower Side Machining
The end cap has to be placed on the lower side by the crimping process. This makes it important
for the lower side to have a appropriate internal diameter and by machining at the lower end we
can make sure of the same. We perform the process on a auto lathe and by a boring tool we
remove the material from the internal side of the tube.
19. Upper Side Machining
The upper side machining is also done to in order to get a proper internal diameter on the upper
side of the outer tube. The process is almost the same except for the fact that boring depth is
more than that in the lower side.
Marking
Roll marking machines offer a fast, efficient method of stamping either round or flat parts.
Consistent marks made with less pressure can be achieved with the use of steel roller dies for flat
parts or type holders with individual type for round parts.
Marking is conducted at the initiation of the fabrication process such that correct model of are
addressed and transferred to correct line and error could be detected on inspection as it indicates
date and shift of manufacture.
Marked Outer Tube
Crimping
One of the open ends of the tube is closed by putting an end cap over it. The lower side of the
outer tube is closed by placing an end cap on it and then applying a hydraulic thrust to crimp it.
The end cap then gets completely fixed to the outer tube and is crimped from five points.
Crimped Outer Tube
20. K. Bracket & LSS Pressing
The crimping of the outer tube is done and now it will be attached with knuckle bracket and the
LSS- lower spring support. The process used for attaching these components is pressing. LSS
and knuckle brackets are pressed to the outer tube that is held in its respective clamps.
Lower spring support & Knuckle Brackets
Hole Punching
In this process of punching the holes to the knuckle bracket by the use of a die and punch
assembly. In this process the knuckle bracket together with the inserted tube are assembled at the
die assembly using a clamping device secondly it also uses pin locators to make the hole in the
other phase of the knuckle bracket. Some stoppers are also used in it and holes are made
according to the required dimensions. After that the process reaches the weld machine where the
knuckle bracket and the LSS as well as the end cap are welded.
Hole Punching Machine
21. Twin Torch MIG Welding
The twin torch MIG welding is a process is a semi-automatic or automatic arc welding process in
which a continuous and consumable wire electrode and a shielding gas are fed through a welding
gun. A constant voltage, direct current power source is most commonly used with GMAW, but
constant current systems, as well as alternating current, can be used. There are four primary
methods of metal transfer in GMAW, called globular, short-circuiting, spray, and pulsed-spray,
each of which has distinct properties and corresponding advantages and limitations.
In this process knuckle bracket and LSS pressed on the tube and lower cap crimped on the
crimping machine are all welded using mig welding. In the mig car welding machine the product
rotates around the gun which is used to weld. The gun requires the copper wire to make the weld.
Basic product parameters to be checked are:
weld strength (knuckle bracket / lower cap)
weld penetration( knuckle bracket / lower cap)
weld strength LSS
weld penetration LSS
weld appearance
Basic process parameters to checked are:
weld voltage k bkt/lower cap(gas argon)
weld current (k bkt / llower cap * gas argon)
weld voltage LSS (gas argon)
weld current LSS (gas argon)
wire dia (k bkt / end cap / LSS)
tip distance to outer tube.
Welded outer tube & Twin Torch Welding Machine
22. Leak Testing
In this process the product is kept into the water and air pressure is applied to it using some
machine. In case if there is any leakage air bubbles comes out of the water which are visual to
the worker and the existence of leakage is checked.
Leak testing Machine
Resizing
In this process resizing of the welded as well as the leak tested product is done using resizing
machine because the dimensions of the knuckle bracket changes due to the punching force etc.
Basic product parameters to be checked are:
1. knuckle bracket width(lower)
2. knuckle bracket width (upper)
Knuckle Bracket Resizing Machine
23. CED & Painting
This process is basically done in order to protect the outer tube from dust, wearing out and
corrosion. The word CED stands for Cathodic Electrodic Dip. In this process the outer tube is
hung on hangers and then sent to the CED & painting section. There they are dipped in various
chemicals in order to create a protective film over them and then they are painted black.
Outer Tube Going to CED & Paint Shop
Outer tube Cleaning
The basic purpose of this process is to get rid of any sort of contamination in the outer tube.
After painting and CED the outer tube might have some contamination on the inner side. Thus
the outer tube is mounted on a six step cleaning machine and then it is thoroughly cleaned with
alkaline, hot and cold water.
Outer tube Cleaning Machine
24. Damper Assembly
Now when the outer tube is ready, we head towards the damper assembly where we will make
the final attachments to the piston rod and convert it to piston rod assembly, attach base valve to
the inner tube etc.
Base Valve Pressing
The inner tube is quite similar to the outer tube except for the fact that all its dimensions are
smaller than the outer tube. The inner tube is also open from both needs to be closed and hence a
base valve assembly that has been riveted from beforehand is attached it with the help of a Base
valve pressing machine in which a hydraulic arm presses the base valve into the inner tube.
Base Valve Pressing Machine
Torquing & Caulking
The finished piston rod is now to be attached with the piston rod assembly but before adoing this
we slip in a few things on the piston rod- Rod guide, DU, non returning spring, oil seal. After
this we fit the piston assembly. Now the piston rod is placed on the torquing and caulking
machine. Here the piston rod is firstly torque ie. A necessary (calculated) amount of torque is
given to it. Post torquing, we do caulking. This is done in order to lock the threads.
Torquing & Caulking Machine
25. Oil Filling
The cleaned outer tubes are sent in the damper assembly through a conveyor and the base valve
attached inner tubes are placed in them. Now we fill a definite amount of oil in it. The oil filled
in the tube is responsible for the damping forces generated in the damper. After filling oil the
torqued and caulked piston rod assembly is inserted in the tube.
Packing Case Seal Pressing
This process is carried out post oil filling. This process is carried out in order to give a proper fit
to the rod guide and also to check length for spinning. A hydraulic arm presses the oil seal from
above doing the required.
Damping Force Testing
This process is done in order to check if the forces provided by the damper are up to the required
standards. The damper is loaded on the machine and then the tensile and compressive forces are
checked for three velocities. A damper is cleared only when it shows a “pass” on the computer
screen.
Gas Filling & Crimping
This step is about filling of Nitrogen gas in the damper and then crimping the outer tube. The
damper is mounted on the machine and then gas is filled to certain pressure. After the gas filling
the outer tube is crimped so as to seal the gas within it.
Gas Filling & Crimping Machine
26. Gas Load Checking Machine
Final inspection is conducted at the end of fabrications of damper to ensure that appreciable
quality of product is being dispatched to the customer. The process checks if the pressure of the
gas filled is appropriate or not.
Gas load Checked Dampers
27. Final Assembly
Now the final assembly will be done and the damper would attached with few more things like
Striker Cap
Dust Cover
Spring
USS- Upper Spring Sheet
Bearing
Bearing Sheet
FHS- front Strut Support
Spring Washer
Hex Nut
After the attachment of the following parts we get the required strut
Struts Ready for dispatch
29. Problem Identification
Sketch Process Sketch Process
..
Material Receipt
& Inspection End cap crimping
.. Transportation LSS & Knuckle bkt
insertion
Outer tube OD
draw
Hole punching
Lower side turning Knuckle bkt welding
Upper side turning Leakage check
Roll marking CED Coating
30. Looking at the above process flow chart we can see that the major problem is observed in the
process of knuckle bracket welding. The leakage begins at the interface where the knuckle
bracket is welded to the outer tube and the end cap.
Due to this the oil filled in the outer tube spills and this leads to reduction of damping forces
produced in the damper.
`
*The above graph shows the number of leakage pieces found in the past four months.
4.03
2.31
3.79
2.74
Feb
Mar
Apr
May
Leakage('00)
Leakage('00)
31. The production of these faulty struts also causes increase in production costs.
*The above Graph shows the cost incurred due to leakage in past four months.
32.24
18.48
30.32
21.92
Feb
Mar
Apr
May
Cost('000)
Cost('000)
32. Measurement & Collection of Data (ALTO CD)
In order to analyze the root cause of the problem it is really important to validate all the
incoming parts and make a check at all the standardized points. The parts that will go under the
check are-
Outer Tube Non Machined
End Cap
Machined Outer Tube
The checkpoints for standard manufacturing that will be validated are
Concentricity of OD1 & OD2 after drawing
Concentricity of lower side post machining of the outer tube
Perpendicularity of the End Cap
Validation of Parts
Outer tube (non machined)
The first part to be validated is non machined outer tube. This is a raw material that is purchase
from outside.
S.no Charachteristics Specification Tolerance Method 1 2 3 4 5 Remark
1 Length 300.6 0.25 H.G. 300.6 300.69 300.6 300.6 300.6 OK
2 Outer Dia 45 0.2 V.C. 45.2 45.19 45.11 45.2 45.19 OK
33. End Cap
The end cap also plays an important part in the functionality of the outer tube. It seals one end of
the outer tube and holds the inner tube within the outer tube. Hence it was the second part to go
under the scanner.
S.No. Charachteristics Specifications Tolerance Method 1 2 3 4 5 Remarks
1 Outer Dia 41.6 0.1 V.C. 41.56 41.56 41.56 41.54 41.56 OK
2 Dimension 1.15 (+)0.2 H.G. 1.74 1.15 1.15 1.15 1.16 OK
3 Hieght 5.3 0.2 H.G. 5.19 5.32 5.17 5.19 5.17 OK
4 Dimension 3.5 (+)0.2,(-)0.4 H.G. 3.7 3.68 3.55 3.7 3.63 OK
5 Diameter 29.4/29.67 - V.C. 29.57 29.63 29.6 29.57 29.62 OK
6 Angle 45 1.5 P.P. 51 - - - - N.G.
7 Total Hieght 12.7 - P.P. 12.54 - - - - OK
8 Angle 30 1.5 P.P. 52 - - - - N.G.
9 Thickness 1.0/1.5 0.5 P.P. 1.29 - - - - OK
10 Radius 30 - P.P. 30.215 - - - - OK
The two dimensions (in red) were not up to the mark and were found to be violating the set
standards of dimensions.
34. Machined Outer Tube
After the end cap validation we again validate the outer tube but this time it is machined. The
outer tube has already undergone drawing, lower side and upper side machining.
S. No. Charachteristics Specification Tolerance Method 1 2 3 4 5 Remarks
1 Length 298.6 0.25 H.G. 298.69 298.48 298.68 298.68 298.68 OK
2 Outer Dia 45 0.2 V.C. 45.19 45.08 45.2 45.2 45.2 OK
3 Chamfer 1.2 0.2 V.C. 1.3 1.3 1.3 1.3 1.3 OK
4 U.side Depth 22 (+)2 V.C. 22.8 22.6 22.6 22.6 22.6 OK
5 U.side I.Dia 41.9 (+)0.1 V.C. 41.78 41.98 41.96 41.98 41.98 OK
6 L.Side depth 4.2 0.2 V.C. 4.03 4.1 4.08 4.08 4.08 OK
7 L.side I. Dia 41.6 0.03 V.C. 41.55 41.6 41.55 41.55 41.55 OK
8 Straightness 0.1/350 - H.G. 0.15 0.14 0.16 0.14 0.12 OK
9 Circularity 0.075 - H.G. 0.05 0.05 0.07 0.06 0.05 OK
Checkpoints for Standard Manufacturing
There are some check points mentioned in the control plan that help us make sure if the process
is being practiced or not. The validation of these check points will give us the idea about the
quality of the machining of the outer tube. We will check three
35. Post OD Drawing Concentricity of OD1 & OD2
This checkpoint makes sure that the OD drawing process is done properly. It checks
concentricity of the two outer diameters that are formed after the drawing process.
S.no. of tube Spec. OD1 OD1 Spec. OD2 OD2 Remark
1 0.5 Max 0.35 0.3 Max 0.2 ok
2 0.5 Max 0.49 0.3 Max 0.29 ok
3 0.5 Max 0.35 0.3 Max 0.25 ok
4 0.5 Max 0.4 0.3 Max 0.25 ok
5 0.5 Max 0.48 0.3 Max 0.23 ok
6 0.5 Max 0.28 0.3 Max 0.2 ok
7 0.5 Max 0.3 0.3 Max 0.18 ok
8 0.5 Max 0.55 0.3 Max 0.26 N.G.
9 0.5 Max 0.36 0.3 Max 0.26 ok
10 0.5 Max 0.4 0.3 Max 0.25 ok
11 0.5 Max 0.45 0.3 Max 0.15 ok
12 0.5 Max 0.3 0.3 Max 0.2 ok
13 0.5 Max 0.32 0.3 Max 0.18 ok
14 0.5 Max 0.3 0.3 Max 0.21 ok
15 0.5 Max 0.28 0.3 Max 0.1 ok
16 0.5 Max 0.56 0.3 Max 0.26 N.G.
17 0.5 Max 0.4 0.3 Max 0.25 ok
18 0.5 Max 0.34 0.3 Max 0.2 ok
19 0.5 Max 0.39 0.3 Max 0.28 ok
20 0.5 Max 0.45 0.3 Max 0.28 ok
We observe that there are three pieces in the twenty inspected pieces that come under the
scanner. Two out of them (marked in red) violate the specification while one(in yellow) is on the
verge of it.
36. Concentricity of Lower Side Machined Post Machining
In this step we checked the concentricity of the vendor side machined depth. This helps us to
make sure if the machining of the lower side of the end cap is done up to the mark or not. If the
concentricity exceeds 0.2 then there is a risk of burning or leakage in the piece.
S.no. of tube Spec. Concentricity Concentricity Remark
1 0.2 0.15 ok
2 0.2 0.16 ok
3 0.2 0.15 ok
4 0.2 0.19 ok
5 0.2 0.14 ok
6 0.2 0.15 ok
7 0.2 0.2 ok
8 0.2 0.17 ok
9 0.2 0.18 ok
10 0.2 0.12 ok
11 0.2 0.25 N.G.
12 0.2 0.19 ok
13 0.2 0.18 ok
14 0.2 0.15 ok
15 0.2 0.15 ok
16 0.2 0.16 ok
17 0.2 0.14 ok
18 0.2 0.15 ok
19 0.2 0.14 ok
20 0.2 0.16 ok
There are four pieces amongst the twenty inspected pieces that come under the scanner. Three of
them (in yellow) are on the verge of specification given while one (in red) violates it.
37. Perpendicularity of the End Cap
The perpendicularity of the end cap is an important aspect. If the end cap’s perpendicularity
exceeds the decided limit then the welding wouldn’t be proper and this might result in leakage.
S.no. of tube Spec. Perpendicularity Perpendicularity Remark
1 0.35 0.3 ok
2 0.35 0.25 ok
3 0.35 0.4 N.G.
4 0.35 0.3 ok
5 0.35 0.14 ok
6 0.35 0.28 ok
7 0.35 0.34 ok
8 0.35 0.31 ok
9 0.35 0.27 ok
10 0.35 0.32 ok
11 0.35 0.3 ok
12 0.35 0.35 ok
13 0.35 0.29 ok
14 0.35 0.3 ok
15 0.35 0.25 ok
16 0.35 0.26 ok
17 0.35 0.25 ok
18 0.35 0.36 N.G.
19 0.35 0.3 ok
20 0.2 0.29 ok
There are two pieces (in red) that violate the perpendicularity standards and only one (in yellow)
threatens to cross it.
38. Relationship between Rate of Nozzle Cleaning & Rejection
Nozzle cleaning has a significant relationship with the rejection rate. If we keep cleaning the
nozzle at regular intervals then we can reduce the number of leakage pieces.
**the above chart shows the relation of rate of nozzle cleaning and leakage.
Analyzing & Identifying the Root Cause
The next step is to identify and remove the shortcomings of the process. We can obtain the root
cause by the help of The Five Why Analysis.
By the help this process we can identify the root cause by asking “WHY” to our problem
statement and then repeating the process with the answer.
10 20 30 40 50 60 70 80
Rejections 0 0 1 3 3 4 5 5
0
1
2
3
4
5
6
RejectionsperNozzleCleaning
Rejections
39. The Five Why Analysis
Our problem statement is- Leakage in Outer Tube.
Thus we can see that the basic shortcoming lies in the Outer Diameter Drawing of the outer tube
and that has been identified as the root cause of the problem.
Process Improvement
The next step is to improve the processes that cause production of faulty dampers. The root
cause identified in the five why analysis is that the Drawing process is not up to the mark and
due to this the forthcoming processes also fail delivering with full effectiveness.
WHY?
• Variation in strength of the weld at various points
around the end cap.
WHY?
• Perpendicularity of the end cap not upto the mark
WHY?
• The variation in wall thickness of the lower side
WHY?
• Due to improper machining of the lower side of the
outer tube.
WHY?
• Lack of concentricity of the OD1 in post drawing
process.
40. Few steps taken
The frequency of nozzle cleaning increased from per 50 pieces to per 20 pieces
The frequency of validation of checkpoints in all the increased to a substantial rate.
Few measures suggested
We need to make sure that the OE’s working at the machine doesn’t deviate from the
control plan. They should follow all the measures and specification mentioned in the
control plan.
The input current & voltage must not be varied as per desire and should be followed as
per the control plan.
Frequency of Maintenance Check of the drawing machine should be increased.
Results after Improvement
We can observe from the graphs below that the there has been significant improvement in the
occurrence of leakage in the past month. For the same reason the cost incurred due to leakage has
also come down.
4.03
2.31
3.79
2.74
1.21
Feb
Mar
Apr
May
Jun
Leakage('00)
Leakage('00)
41. *The above graph shows the improvement made in number of leakage occurred in the last month as
compared to the previous four.
*The above Graph shows the improvement in the last month in the cost incurred due to leakage
as compared to the past four months.
32.24
18.48
30.32
21.92
9.68
Feb
Mar
Apr
May
JUN
Cost('000)
Cost('000)
42. Summary
The problem we are facing is leakage in outer tube. This problem is a result of various
shortcomings that are occurring before the knuckle bracket welding. The basic problem lies in
the drawing operation and that continues further.
The number of leakage pieces last month was 274 pieces and it cost rupees 21920 to the
company.
The conclusion we draw from all the above operations are
The Concentricity of the OD1 should be within the specification.
The Perpendicularity of the end cap should be not more than 0.35
The rate of nozzle cleaning should be- per 20 pieces.
Following the all these measures we minimize the leakage in outer tube. The number of pieces of
leakage this month are 121 pieces and the cost reduced to rupees 9680.
