Report on REJECTION REDUCTION IN CPC RING

A REPORT
ON
SUMMER TRAINING INTERNSHIP IN
ON TITLE
REJECTION REDUCTION IN CPC (COMPOSITE PLATING OF
CHROME) RING
SUBMITED TO
ASET, Amity University, Noida
BATCH: 2011-2015
SHRIRAM PISTONS AND RINGS PVT. LTD. SUBMITTED BY:-
REPRESENTATIVE: K.VENU GOPAL
MR. ROHIT KUMAR ROLL NO. - A2305411030
ENGINEER, C2D1 PLANT

i
CERTIFICATE
This is to certify that Mr. K.Venugopal of Amity School of Engineering and Technology, Amity
University, Noida (U.P.) has been provided with industrial training in Shriram pistons and rings
Pvt. Ltd. (Ghaziabad) for the period of 8 weeks from 02/05/2014 to 25/06/2014 under my
guidance. During this period he has successfully completed the project “REJECTION
REDUCTION OF CPC RING”
Rohit kumar K.Venu gopal
(Guide)

ii
ACKNOWLEDGEMENT
I would like to express my gratitude to everyone who supported me and gave me a possibility to
successfully complete my project. A special thanks to our project guide, Mr.Rohit kumar,
Engineer, C2D1 Plant, whose help, stimulating suggestions and encouragement helped me to
coordinate my project and especially write this report. His constant support and guidance
throughout the course of the project has made the project reach its successful completion. Their
suggestions were indispensable in preparing ourselves to meet the challenges posed by the
project.
I would also like to thank Shriram Pistons and Rings Pvt. Ltd, which gave me all the liberty to
explore and understand the concepts of manufacturing on shop floor. I would like to thank my
faculty guide Mr. Prashant Gill of Amity University & Mr. Vivek Kumar, H.O.D (MAE) of
Amity University for guiding all my way throughout this project.
Last not the least I would like to thank my parents, seniors and friends without whose kind
support I could not have undergone the project smoothly & successfully.
I thank all those who knowingly and unknowingly have helped me in the fulfilment of this
project, I would like to heartily thank all of them.

iii
COMPANY PROFILE
Shriram Pistons & Rings Ltd. (SPRL) is one of the largest and most sophisticated manufacturers
of precision automobile components i.e. pistons, piston rings, piston pins and engine valves in
India. The products are sold under brand name ‘USHA/SPR’ in the markets.
SPRL manufacturing unit is located at Meerut road in Ghaziabad (25 km from Delhi). The plant
has been recognized as one of the most modern and sophisticated plants in north India in the field
of automobile the production capacity of plant is as under:
 Piston : 17.06 million per year Actual Production in 2011-2012
 Pin : 14.9 million per year Actual Production in 2011-2012
 Rings : 76.5 million per year Actual Production in 2011-2012
 Engine valves : 33.8 million per year Actual Production in 2011-2012
The company has technical collaboration with:-
 M/s. Kolbenschmidt, Germany to produce pistons
 M/s. Riken corporation, Japan for piston rings
 M/s. Fuji Oozx, Japan for the manufacture of Engine Valves
 M/s. Honda Foundary, Japan for technical support
The company supplies its products to several Original Equipment Manufacturers (OEMs) like
Ashok Leyland, Tata Cummin, Tata Motors, Maruti Suzuki, Mahindra & Mahindra, Tafe
Tractors, SML( Swaraj), Kirloskar Oil Engines, Bajaj Auto, Honda Siel Cars, Sundram
Claylon, Honda Scooter, International Tractors, Standard combine in addition to all the Honda
Joint ventures in India. SPRL is also supplying its products to international OEM’s like Renutt,
Nissan, Ford and Riken etc.
At Shriram Pistons and Rings Ltd. Quality is an integral part if whatever we do, which is
reflected in the company’s Quality Policy:
“Total Customer satisfaction through Quality Management and Continuous Improvement”
Quality Objectives:-
 Organisation which is sensitive and interactive to the needs of customer.
 Continuous upgrading of quality and process to meet changing needs of customer.
 Optimization of return on investment by-
 Continuous improvement
 Technology development

iv
 Organizational and personnel development
 Cost reduction efforts
 Effective use of all resources
 Harmonious and safe working conditions
 Work to international norms of quality and management.
The company has successfully practiced the best work ethics and technology along
with the TPM & Kaizen approach and harmony through teamwork.
 Achievements in terms of quality:
 SPR received the ISO-9001 certificate from RWTUV, Germany in 1994.
Technology from the collaborators was supplemented with In-house efforts and
by implementing world-class practices.
 The company received QS-9000 certificate from TUV, Germany in the year
1999.
 The company received ISO-14001 certificate in the year 2001.
 SPR received the TS-16949 certificate in the year 2003.
 The company received OHSAS-18001 certificate in the year 2003.
 Best foundry awards from institute of Indian Foundry men in the year 2003.
 Green rating award by CII, U.P.Pollution Control Board & World Bank in
2004.
 The company received TPM Excellence award in the year 2004.
 Received Diamond Award – overall Best performance in QCDDM, outstanding
performance in cost, bronze award for delivery, gold award for 5S from Honda
Siel Cars(I) Ltd. In 2006.
 SPRL has received the Best Vendor Awards from Maruti Suzuki for 4
consecutive times, Best supplier performance awards from Tata Cummins Ltd
for 3 consecutive years. And has self-certified status with most of the OEMs.
 Excellence award in Export by government of India.
 Excellence award in productivity by ACMA in 2007-08.
 Excellence award in quality by Honda Scooters and Motor Cycles Limited,
 Excellence award in technology by ACMA in 2007-08.
 Excellence award in manufacturing excellence award by ACMA in 2007-08.
 Received silver trophy- technology from ACMA in2007-08.
 Received outstanding supplier for technology award from Cummins in 2007-
08.
 Received vendor performance award Kaizen, vendor performance award
overall commendation, overall achievement trophy from Maruti Suzuki in
2007-08

v
 The company received recognition award by government of India for In House
R. & D.
 Best foundry award received from Institute of Indian Foundry Men.
 Received star performer(IC Piston Engine & Parts) award from Engineering
Export Promotion Council (EEPC) India.
 Received silver award – Quality & Bronze award – spares from Honda Siel cars
India ltd. In 2007.
 The company received TPM special award in march 2008
 Received Best Quality Vendor award from Tata Motors ltd. In 2008-09.
 Received best vendor award for overall performance (QCLDM) from Ashok
Leyland in 2008-09.
 Received overall achievement trophy from Maruti Suzuki in 2008-09.
 Received best explorer award from FIEO- Federation of Indian Export
Organisation in 2009-10.
 Received Trophy from EEPC “STAR PERFORMER IN PRODUCT GROUP
OF ENGINES, TURBINES & PARTS” in recognition of outstanding
contribution to engineering exports during the year 2008-09.
 ISO/TS 16949 achieved for SPR Unit-II – Ghaziabad in year -2009.
 ISO/TS 16949 achieved for SPR Unit V pune in year 2010.
 Received performance award form Honda siel Power products Ltd. In march -
2012.
Features of SPR factory:
 Total area covered by the factory is 27 Acres.
 The factory has manufacturing facilities for piston, rings, pins and engine valves.
 Classification of the premises:
P.T.E- Production Technology and Engineering
C.A.A- Commercial Administration and Accounts
R & D- Research and Development
 Total strength of the company is 5230 nos. consisting of officers, staff and workers.
 The turnover/sales for the year 2011-12 are Rs. 1000.00 Cr.
 The company is exporting or more than 35 countries.
 Exports sales are of Rs. 188 Cr. year 2011-2012.
 Over 10% of the production is exported to sophisticated markets such as Europe, UK,
Egypt, USA, Latin America etc.
 SPR has been investing 30% of its retained earnings in quality upgradation and
modernization every year.

vi
VISION
 World Class Company, Preferred by World Class Customers
 Motivated, Dedicated and System Oriented Employees
 Safe and Healthy Work Place
MISSION
 Sales and profit growth/leadership
 Strong leadership with collaborators
 Preferred OE supplier
 Employee development
 Superior returns to stake holders
 Care for environment and society.
OTHER MANUFACTURERS COMPANY IN INDIA:-
There are following Manufacturers Company of piston, piston ring, piston pin and engine valves
in India which is given below
 SAMKRG Piston & Rings – Andhra Pradesh
 (IPL)India Piston Limited (A Group of Amalgamations) – Chennai
 (SSPPL) Sintered Product Pvt. Ltd. –Headquartered in kosi kalan (North India)
 (AIP) Abilities India Piston & Rings Ltd – Ghaziabad
 Shriram Piston & Rings Ltd – Bhiwadi.

C O N T E N T
i. CERTIFICATE
ii. ACKNOWLEDGEMENT
iii. COMPANY PROFILE
1. INTRODUTION………………………………………………………………………[1]
1.1 COMPRESSION RING…………………………………………………………...[1]
1.2 SECOND RING…………………………………………………………………...[2]
1.3 OIL CONTROL RING…………………………………………………………….[2]
2. ABOUT THE PLANT………………………………………………………………....[2]
3. PISTON RING SHAPE………………………………………………………………..[4]
4. TYPES OF RING MADE IN THE PLANT………………………………………….. [5]
5. TYPES OF RING PROFILE…………………………………………………………..[6]
6. PROCESS SEQUENCE……………………………………………………………….[7]
7. MACHINING OPERATION DETAIL………………………………………………..[8]
7.1 GRINDING SECTION…………………………………………………………….[8]
7.1.1 ROUGH SIDE FACE GRINDER………………………………………….[8]
7.1.2 SEMI FINISH GRINDER………………………………………………….[9]
7.1.3 FINISH SIDE FACE GRINDER…………………………………………..[9]
7.2 LINE 1 SECTION………………………………………………………………….[10]
7.2.1 CAM TURNING AND GAP CUTTING MACHINE……………………..[10]
7.2.2 INTERNAL BORING MACHINE………………………………………...[11]
7.2.3 HONING MACHINE……………………………………………………...[12]
7.2.4 PROFILE TURNING MACHINE…………………………………………[13]
7.2.5 GROOVING MACHINE…………………………………………………..[14]
7.3 PCM SECTION……………………………………………………………………[14]
7.3.1 GAP GRINDING MACHINE……………………………………………[15]
7.3.2 GAP EDGE CHAMFER MACHINE……………………………………[15]
7.3.3 PROFILE GRINDING MACHINE………………………………………[16]
7.3.4 PARKERISING……………………………………………………………[17]
8. DEFECTS OCCURRED DURING MACHINING OPERATION……………………[18]
9. REJECTION ANALYSIS METHODOLOGY………………………………………[18]
9.1 TRACK OF THE LOT FOR REJECTION ANALYSIS…………………………[19]
9.2 PARETO ANALYSIS……………………………………………………………[20]
10. PREVIOUS IMPROVEMENTS TO REDUCE REJECTION………………………[20]
10.1 PROCESSING OF ALL CPC RINGS BELOW 120MM DIAMETER ON AUTO
OD GAP CHAMFER MACHINE…………………………………………………[20]
10.2 BEARING UNIT NECK THICKNESS REDUCED TO AVOID CHROME
BROKEN AT GAP DURING PROCESSING OF RINGS ON BORING
OPERATION…………………………………………………………………….[21]
11. SUGGESTION FOR REJECTION REDUCTION FOR FUTURE SCOPE………..[22]
11.1 SUGGESTION OF IMPROVEMENT………………………………………[23]
12. CONCLUSION………………………………………………………………………[24]
13. REFERENCE………………………………………………………………………….[24]

1. INTRODUCTION
Piston ring can be perfectly defined as the split ring with slight adjustment of diameter which fits
around the groove of the piston and seals the gap between the piston and cylinder wall.
Piston rings are widely classified into two types:
1. Compression ring
a. Top ring
b. Second ring
2. Oil control ring
Each of these rings uses distinct combination of materials, shape, heat treatment and surface
coating in contemplation of performance of its assigned function in optimality manner. The
design of these rings is a very critical job to carry upon to make it function properly. Its design
are made with respect to the combination of number of these rings in an engine. Some engine
requires 2 or 3 rings ranging till 6 per piston.
Functions of the rings –
Piston rings must accomplish three major principle functions,
 Seal off the combustion chamber from the fuel mixture entering the crankcase
 Limit and controlled regulation of oil consumption
 Transfer the heat absorbed by the piston in the combustion process to the cooled cylinder
walls.
1.1 TOP RING-
This ring sit on top portion of the piston also referred as the upper compression ring. This ring is
operated at high thermal and mechanical loading. Its function is to form a gas-tight barrier
between the cylinder walls and the piston in order to the seal the combustion chamber. Another
function is to transfer the heat generated to the cylinder wall from piston and act like a bridge
between them.
Figure 1 Top ring

1.2 SECOND RING-
This is known as the lower compression ring. Its function is to work cumulatively with the top
ring to seal the combustion chamber and transfer the heat to the cylinder walls. These rings also
control oil ring. It does the job of both compression ring and oil ring.
1.3 OIL CONTROL RING-
It regulates and limit oil consumption. They scrape off excess lubricating oil from the cylinder
walls and return it to the crankcase. They are designed to provide a thin oil film to ensure piston
and ring lubrication. Improper control results in carbon residues or blue smoke in the exhaust gas
and results excessive oil consumption.
Application of piston ring is very wide. Some of them listed below-
Motor cycles, Passenger cars, Buses, Trucks, Motorsports, Large agriculture power generations,
Marine propulsion, Leisure RV’s, Small agriculture lawns and garden, Leisure crafts.
2. ABOUT THE PLANT
The factory located at Ghaziabad produces mainly three products pistons, piston rings and engine
valves. The piston ring has two plant namely C.I. Ring plant and the C2D1 Ring plant. The
C2D1 Ring plant is the point of interest in this project. The C2D1 plant is technically named
after the size of diameter made in this plant. C2 refers to the size range 121-140 mm and D1
refers to the size range 141-150 mm. C2D1 plant is the only plant which produces the chrome
rings.
Material used for manufacturing these piston rings are S.G. iron which is also known as the
ductile iron. Material which are widely used are as follow-
RIK- 10, RIK- 20a, RIK- 40B, RIK- 40S, SPR-02
Elemental composition chart of these materials are below-
Figure 2 Second ring
Figure 3 Oil control ring

Figure 4 Table showing all
material composition

3. PISTON RING SHAPE:
Piston ring shape can be classified into three part according to the ovality namely:
1. Positive ovality: The measurement of the positive ovailty is done with the ring at its
free state. If the dimension of the ring measures from the back of the ring to the tip is
larger than the diameter measured across 90 degree, then the ring is said to be having
positive ovality. This causes an effect at the tips by the joint exert a high pressure against
the cylinder than other area of ring. This prevents the ring tips ‘fluttering’ at higher
engine speeds. Such rings are normally only specified on engines with higher RPM.
2. Negative ovailty: The measurement of the negative ovailty is done with the ring at its
free state. If the dimension of the ring measures from the back of the ring to the tip is
smaller than the diameter measured across 90 degree, then the ring is said to be having
negative ovality. Rings are specified with negative ovality to compensate for expansion at
operating temperature. As the ring warms, the heat can be concentrated at the ring tips.
These try to expand outwards, and by designing a ring with negative ovality, this effect
can be negated to create a ring exerting more even pressure around its circumference.
Rings with negative ovality were formerly used on slow speed 2-stroke diesel engines,
and are today widely specified on medium speed 4-stroke diesel engines.
3. Zero ovality: The measurement of the zero ovailty is done with the ring at its free state.
If the dimension of the ring measures from the back of the ring to the tip is equal to the
diameter measured across 90 degree, then the ring is said to be having zero ovality. Rings
with zero ovality are frequently specified for the latest slow speed 2-stroke diesel
engines.
Figure 5 Diagram depicting all the types of ovality

4. TYPES OF RING MADE IN THE PLANT:
Oil Ring
Plain Oil ring Oil chrome
HTCR
HTCR PGV
Compression ring
Chrome
Compression ring
K.S. Chrome
Taper K.S.
Chrome
Taper Chrome
K.S. Chrome
PGV
Plain
Compression ring
Taper
K.S. Compression
Taper K.S.
Taper Comp. IDB
Taper Comp. IDS
Plain
Taper napier
ODS Plain/Taper

5. TYPES OF RING PROFILE:
Napier ring: The Napier ring (also known as a Nasen ring) has a step machined into the lower
part of the running face. The upper part of the running face may be either square or with a taper.
Such a ring has a twisting effect when closed which allows the ring to
present a sharp downward edge to the cylinder which is effective at scraping
excess oil from the liner. The step provides a large area into which this oil
can be stored.
Rectangular Ring: Simple design with a square running face. Such rings are often un-coated, and
since the full ring face sits against the cylinder liner, such rings have a
relatively low contact pressure.
Taper faced: The taper faced ring allows the contact area between the ring and cylinder liner to
be reduced, thus proportionately increasing the contact pressure with the cylinder. Additionally
there is some pressure relief due to combustion gas pressure between the
top of the ring and the liner pushing the ring inwards. Such rings have
reduced running-in times and also provide some oil scraping function.
Internally Stepped Ring/Internal Chamfered Ring: By machining a step or a bevel onto the top
inside corner of the compression ring, the ring becomes subject to a twisting
or torsion effect when closed to working size and fitted into the liner. This
feature causes the bottom outside corner of the ring to make contact with the
cylinder liner thus providing good running-in characteristics and improved
oil scraping function. When combustion gas pressure is applied, the ring
running face is pushed flat against the liner.
Keystone Ring: This ring has a wedge shaped section. Thus the side faces of the ring are tapered.
This allows the clearance between the ring and the piston groove to vary as
the ring moves radially within the groove. This feature greatly reduces the
ring sticking in the piston groove, and is useful where the engine is for
some reason producing heavy combustion residues.
Slotted Oil Scrapper: Otherwise designated as SOC type this ring, has two scraping edges
separated by a groove. In the bottom of the groove are a number of slots
running to the inside of the ring. These allow oil gathered by the two scraping
edges to flow through, and be dispersed back into the engine via drain holes
drilled into the bottom of the piston groove. Such a ring can be supplied in
many different forms. The simplest and oldest is shown to the right with
square scraping edges.

6. PROCESS SEQUENCE
Figure 6 Process
flow diagram
production line

7. MACHINING OPERATIONS DETAIL
In C2D1 plant has a wide and huge space to accommodate various high-tech machining
equipment. The machining operations are divided into mainly three categories:
1. Grinding section
2. Line 1 section
3. PCM
The making of piston rings starts with the casting of the ring from molten metal
7.1 Grinding section-
Grinding section consist four machines namely rough grinder, semi-finish grinder, finish grinder,
and plunge grinder.
7.1.1. Rough side face grinder- Rough grinding machine is where the first operation starts. The
casted ring is first grinded in the rough grinding machine. In this operation the axial height of the
ring is decreased. About 1000-2000 microns of material is scraped out during this process. This
machine has got two grinding wheel horizontally placed in-between which the ring is passed. In
the input of the machine a slow moving v belt carrying the rings pass it to the machining portion,
where the grinding wheel is placed. The two grinding wheel are responsible for the stroke
removal. The output is constantly inspected for its axial height using a screw gauge.
Following are the brief detail of the machine unit:
Materials machined: - RIK -40B, RIK-40S, RIK-10, RIK-20A, RIK-25H and SPR-02
Tooling detail: -
1. Grinding wheel- 760x70x25.4 mm
2. Grinding wheel surface structure- Honeycomb
3. Grinding wheel material carborundum
4. Grinding wheel R.P.M.- 600-660 rpm
5. Dresser- Single pipe diamond dresser (0.75 carat)
6. Coolant- CIMSTAR (4.5-6 % max)
7. Guide strip- Thickness< axial height
Defects occurred-
1. Bad face- Irregular pattern on the radial face
2. Burn- Surface burned with black patch
3. Broken ring- Ring broken due to cracks
Figure 7 Diagram showing an
example of burn defect

7.1.2. Semi-finish side face grinder- Semi finish grinding machine is where the second operation
starts. The rings after rough grinding is further machined in this machine. In this operation also
the axial height of the ring is decreased. About 150-200 microns of stroke is removed out during
this process. In input the rings are placed on the v shaped platform. This platform is attached
with a vibrator which helps in the forward movement of the rings. After this the rings are
displaced to the magnetic rotary drum which carries the ring to the grinding wheels for
machining to be done. Machined rings are brought adjacent to the input side by means of a
conveyor belt. On output the rings are inspected for the axial height.
Tooling detail: -
Defects occurred-
7.1.3. Finish side face grinder (plunge/diskus grinder) - Finish grinding machine is where the
third operation starts. The rings after semi finish grinding is further machined in this machine. In
this operation also the axial height of the ring is decreased. About 4-5 microns of stroke is
removed out during this process. These machines are vertical type whereas the rough and semi
finish grinders are horizontal type. These are fully autonomous machine. It is also built with two
grinding wheels but are vertically placed. The rings are stacked at input which is then passed to
the carrier plate. Carrier plate are circular disc with holes at 120o
each. With the ring engaging to
the hole, the plate rotates and the rings are machined. After that the rings are robotically
collected through collector unit.

Tooling detail: -
Defects occurred-
7.2 Line 1 section:
After the grinding operation is done at line 1 the ring gets into the shape and profile. This section
consists of machines like cam turning, internal boring, honing, grooving, I.D. step and profile
turning.
7.2.1 Cam turning and gap cutting machine: Cam turning machine is a special turning
machine designed specifically for machining the piston ring. Since the rings are
initially oval in shape round turning is not possible, cam turning machine is used to
turn the oval shape. In order to start the process a no. of rings are stacked and
clamped in a cylindrical rod and levelled using a v block. The cylindrical rod is then
clamped to the machine. With the required setting according to the type of ring the
machining takes place over the outer surface i.e. along the axial height. After this the
rod is transferred to the gap cutting machine. Here using two parallel milling cutter
the gap is cut on the rings. With the rings with the gap is oval shaped and closing the
gap the shape changes to round. With the oval shape the gap is called free gap and
the round shape is called as closed gap with the precision of 0.00 mm.

Materials machined: - RIK -40B, RIK-40S, RIK-10, RIK-20Aand SPR-02
Tooling detail: -
1. CAM%- Selected as per process card
2. Ovality- Selected as per process card
Gap cutting tooling detail:
Material Diameter Feed value reading RPM Cutting material
RIK-40B/40S 40-100 400-450 250-300 H.S.S / Carbide
RIK-10/20A, SPR-02 40-100 400-450 250-300 Carbide
RIK-40B/40S 100.1-120 350-400 250-300 H.S.S / Carbide
RIK-10/20A, SPR-02 100.1-120 300-350 250-300 Carbide
Defects occurred-
1. Face dent- Dent present on the axial face
2. OD unturn- Incomplete machining on the outer surface
3. Unshape- Irregularity in dimension of radial distance
7.2.2 Internal boring machine: Internal boring machine is used to bore the internal side
face of the ring. This operation is followed by the cam turning operation. Tool used
in this operation is a five single point cutting tool attached to a thick disc shaped
attachment. This machine consist of vertical motor which rotates the spindle which
is attached to the tool. Rings are stacked to the machine in such a way that the
spindle is right at the internal portion of the ring. As the vertical motor starts the tool
rotates and bore the internal part of the ring.

Tooling detail: -
RING DIAMETER BEARING UNIT DIA.
57-74(& 74 OVER SIZE) 50,55
76-96(& 96 OVER SIZE) 65
98-108(& 108 OVER SIZE) 75
110-128(& 128 OVER SIZE) 90
130-150(& 150 OVER SIZE) 100
HOUSING RING DIA.
SMALL HOUSING 38~96
MEDIUM HOUSING 97~140
LARGE HOUSING 141~150
Defects occurred-
1. ID lining- Incomplete machining on the inner surface
2. ID burr- Burr at the inner surface
3. Gap broken- Gap is broken
4. Chrome broken- Chrome coating is broken
5. ID unturn- Incomplete machining on the inner surface
6. ID vibration- Irregular pattern due to vibration
7.2.3 Honing machine: Honing operation is one of the crucial operation in piston ring
production. During the cam operation the outer surface is machined with lining. This
lining has to be polished in order to get a smooth outer surface for further machining.
Honing sleeve selection is the first step in this operation, which is selected according
to the process card. After this the rings are stacked in the mandrel with intermediate
collars. The mandrel is inserted into the sleeve. The abrasive texture in the inner
surface of sleeve is responsible for polishing the outer lining of the ring. This
abrasive operation takes place through two motions, one is rotational and other is
translation motion. The spindle rotates along with vertical linear moment. This
process goes through no of cycles for specified time. This time is known as the
lapping time.

Tooling detail: -
1. Honing sleeve- Punch mark for diameter
2. Collar- Punch mark for diameter & Angle
3. Honing mandrel- As per ring diameter
4. Coolant- Fresh servo 46 mixed with 35gm 1000 grit emery
5. Dummy ring- 2-3 rings
Defects occurred-
1. Chrome broken- Chrome plating at outer surface
2. Granular plating- Granular patch on the surface
3. Dechrome- Chrome coating removal
4. Rehoning- This occurs improper machining
5. Gas leakage- Minute hole due to casting defect
6. Patch- Patch on the surface of the ring
7. Twisted ring- Twist in the split ring
8. Chrome at gap- Chrome plating broken at gap
7.2.4 Profile turning machine: Profile turning machine is where the ring is distinctly get
into shape. Each ring has specific function to accomplish and this is done through
ring profile design. Profile of ring is designed by a team of engineers with the
demand of the customer. Profile are made on the ring using computer controlled
lathe machine. In order to increase productivity and rejection five single point
cutting tool are combined and used to machine five ring at a time. Rings are stacked
in a string wrench with a dummy disc in between two rings. After that the rings are
clamped to the lathe machine and tightened. Following this machining takes place
and profile are generated.
Tooling detail: -
1. Basic collar left- D2= (D+0.5/D+0.3) SDE1.3/TD
2. Basic collar right- D2= (D+0.5/D+0.3) SDE1.3/TD
3. Distance collar- D1 Thickness as per chart
4. Clamping sleeve- D+0.5/ D+0.7/ D+0.3/ D+0.09 mm

5. Tool- as per the chart
Defects occurred-
1. OD unturn- Incomplete machining on the outer surface
2. Face dent- Dent present on the axial face
3. Vibration- Irregular pattern due to vibration
4. Profile centre- Shift in the centre of the profile due to improper machining
7.2.5 Grooving machine: Grooving machines are used to create groove on the side face of
the ring. Grooves are made to dispense the scraped oil around the piston groove.
These scraped oil is passed through the groove and transferred to the oil drain hole.
Groove machine contain a stack of multi point cutting tool clamped in a cylindrical
rod structure. Stack of ring is also clamped parallel to the cutting tool in such a way
that the middle portion of side face of the ring is exactly adjacent to the cutting tool.
With the rings remaining static cutting tool rotates and make the groove. The
machine is computer controlled and the cutting tool retracts back then stack of ring
rotates to change the side face for new grove machining.
Tooling detail: -
LIMITING PRESSURE
HTCR PGV/ IDCR (D+0.15) mm
HTCR (D+0.35) mm
PLAIN OIL (D+0.75) mm
HTCR CHROME (D+0.75) mm
SLEEVE/ COLLAR SIZE
25-30 kg/cm2
30-35 kg/cm2
Defects occurred-
1. Chrome broken- Chrome is broken at the slot
2. Face dent- Dent present at the surface
3. Vibration- Irregular pattern on the surface of the ring
7.3 PCM section:
PCM section is most intricate section in piston ring production. Every machining has to be taken
care of, even small irregularity could cause increased rejection. The word PCM stands for post
chrome machining which by name suggest that this section is works on ring after chrome plating

is done. This section consist of machines like gap grinder, gap edge chafer, profile grinder,
honing, and keystone grinding.
7.3.1 Gap grinding machine: After the chrome plating procedure one of the main
operation is gap grinding. This operation is very critical because of its contribution
to the rejection of the ring. Due to this reason this machine is always been a point of
interest for many engineers working on rejection reduction. Gap grinder is a
computer controlled machine having a grinding wheel which fits in between the ring
gap and grind it. A no. of ring are stacked and hanged in a T shaped bar. An arm is
provided to release single or a set of rings at a time. Ring is then grinded at the gap
with heavy supply of coolant in order to reduce chrome broken. Single ring or set of
rings are machined at a time according to the axial height of the ring. After the
machining the ring is then pushed through the sleeve and collected at the other end
of the machine.
Tooling detail: -
1. Grinding wheel- 125x1.5x22.23 mm
2. Grinding wheel designation- CB200R100BK8
3. Grinding wheel material- CBN (Cubic boron nitride)
4. Grinding wheel R.P.M.- 6000±200 rpm
5. Coolant- CIMSTAR (4-6 % min)
No. of rings per stroke Axial height
4 Up to 1.7 mm
3 1.7< B <2.5
2 2.5< =B <6
1 6< = B & Above
Defects occurred-
1. ID gap broken- Gap is broken at the inner surface
2. Slant gap- Gap cut is not proper
4. OD scratch- Scratch at the outer surface
7.3.2 Gap edge chamfer machine: Gap edge chamfer machine is used to create chamfer at
the gap edge. Chamfering is done to reduce stress concentration at the gap edge. This

machine is fully computerised, the ring is stacked in a T-shaped bar. Then a picker
arm picks few no. of ring and pass it for the machining. Two abrasive belt are
clamped of either side to chamfer the edge on both side. After then the rings are
collected in the T bar on the other side.
Tooling detail: -
1. Belt specification- 240 grit (10x350)
2. Sand paper- 80 grit (20mm dia.)
Defects occurred-
1. Chrome broken at gap- Chrome coating is broken at the gap
2. Chamfer unequal- Unequal machining of the chamfer
7.3.3 Profile grinder machine: Profile grinding machine is used to grind and polish the
outer surface of the ring. This machine uses a huge grinding wheel which grinds the
outer surface. Rings are clamped to the machine and grinding wheel grinds the side
face of the ring.
Tooling detail: -
1. Collar diameter- As per process card
2. Collar thickness- As per stage card
3. Dresser point- R0.2, 55o
4. Sleeve dia.- As per process card
5. Mandrel dia.- ɸ 69.6~ 106=58 mm, ɸ 106>80 mm
Defects occurred-
1. OD edge broken- Outer surface edge is broken
2. OD vibration- Irregular surface on the outer face
3. OD unground- Irregular machining on the outer surface

7.3.4 Parkerising: Parkerising is a chemical process done to make corrosion resistant ring.
A Piston ring has to work in extreme condition in such case corrosion is unbearable.
In order to prevent the ring from corrosion and make it wear resistant Parkerising
coating is applied on the ring. It is a method of protecting a steel surface from
corrosion and increasing its resistance to wear through the application of an
electrochemical phosphate conversion coating. Parkerizing is usually considered to
be an improved zinc or manganese phosphating process, and not to be an improved
iron phosphating process, although some use the term parkerizing as a generic term
for applying phosphating (or phosphatizing) coatings that does include the iron
phosphating process. Parkerizing is commonly used on firearms as a more effective
alternative to bluing, which is another electrochemical conversion coating that was
developed earlier. It's also used
extensively on automobiles to
protect unfinished metal parts
from corrosion. The Parkerizing
process cannot be used on non-
ferrous metals such as
aluminium, brass, or copper. It
similarly cannot be applied to
steel containing a large amount
of nickel, or on stainless steel.
Passivation can be used for
protection. Detailed flowchart of
the Parkerising process is shown.
Figure 8 Process flow diagram of parkerising operation

8. DEFECTS OCCURRED DURING MACHINING OPERATION:
The following list is the visual standard of the defect-
9. REJECTION ANALYSIS METHODOLOGY:
The process of analysis for rejection goes through various steps. To start with, the initial process
is to track and record rejection in each lots of ring. Then with all the recorded data Pareto
analysis is done. Pareto analysis is done in such cases where many possible causes are competing
and have to prioritize which cause is to be taken care of first. With the results from Pareto
analysis the defect contributing the most is selected and analysis are done on that particular
defect first. Following this there is a brainstorming session, where people operating the
respective machine causing the defect are called and asked for the reason for the defects. Then
after various careful calculation and experimentation solution for the rejection reduction is
established.

9.1 Track of the lot for the rejection analysis:
After tracking two lot of ring for the characteristics of defects occurred at each step of operation
it is been observed that chrome broken has a major contribution to the rejection. The lot which
was tracked are model XXX and YYY
1. Model name- XXX
Model type- CPC RING with KEYSTONE PROFILE
Material- RIK- 20A
Nominal dia. - 104.00 mm
Initial no. of rings in the lot- 2680
No. of rings before keystone operation- 2465
No. of rings at final inspection- 2236
Total rejection- 444
Rejection percentage- 16.56 %
2. Model name- YYY
Model type- CPC RING with KEYSTONE PROFILE
Material- RIK- 20A
Nominal dia. - 88.90 mm
Initial no. of rings in the lot- 2625
No. of rings before keystone operation- 2440
No. of rings at final inspection- 2312
Total rejection- 313
Rejection percentage- 11.92 %
CRI Inspection report for the YYY

It is been observed from the CRI report that the chrome broken has the major effect on rejection
rate. An average of 61.5 % of the whole rejection is chrome broken. After tracking and analysis
of the rejection rate it is been finalised that chrome broken is major contributor to the rejection
and studies is to be done on this defect.
9.2 PARETO ANALYSIS:
Pareto analysis is done on these models for prioritizing the causes and selecting the key
contributing cause. Pareto analysis graph is shown below-
From the graph top 4 defects are chosen along with the action plan which are as follow-
 Chrome broken at gap (9.5%) - Action plan has been made for chrome broken at gap
 Chrome broken at O.D. (2.3%) – 64% reduction
 O.D. scratch (0.6 %) – 78% reduction
 O.D. gap edge chamfer (0.09%)
10. PREVIOUS IMPROVEMENTS TO REDUCE REJECTION:
 Processing of all CPC rings below 120mm diameter on auto OD gap chamfer machine
 Processing of all CPC rings on D-150 cam turning machine
 Buffing of entry portion of honing sleeve started to avoid chrome broken at O.D. during
insertion of mandrel in sleeve
 Bearing unit neck thickness reduced to avoid chrome broken at gap during processing of
rings on boring operation
10.1 Processing of all CPC rings below 120mm diameter on auto OD gap chamfer machine:
Auto gap edge chamfer machine is used to create chamfer at the gap edge. Chamfering is done to
Figure 9 Pareto analysis chart

reduce stress concentration at the gap edge. This machine is fully computerised, the ring is
stacked in a T-shaped bar. Then a picker arm picks few no. of ring and pass it for the machining.
Two abrasive belt are clamped of either side to chamfer the edge on both side. After then the
rings are collected in the T bar on the other side.
All CPC ring below 120mm diameter are more prone to defects and has to be carefully handled.
For this purpose automatic gap edge chamfering machine is used. Figure of gap chamfering
machining process is given below.
10.2 Bearing unit neck thickness reduced to avoid chrome broken at gap during processing
of rings on boring operation: Internal boring machine is used to bore the internal side
face of the ring. This operation is followed by the cam turning operation. Tool used in
this operation is a five single point cutting tool attached to a thick disc shaped
attachment. This machine consist of vertical motor which rotates the spindle which is
attached to the tool. Rings are stacked to the
machine in such a way that the spindle is right at the
internal portion of the ring. As the vertical motor starts
the tool rotates and bore the internal part of the ring.
After the rings are machined they are passed through
the bearing unit. Since the neck of bearing unit is
thick it leads to slight expansion of gap and
ultimately the chrome is broken at the gap. To overcome
this the thickness of neck is reduced. Detailed diagram of
the bearing unit is given below.
Figure 10 Diagram depicting the edge chamfer operation Figure 11 Diagram depicting internal
edge chamfering operation
Figure 12 Diagram depicting the neck thickness
change in bearing unit

11. SUGGESTION FOR REJECTION REDUCTION FOR FUTURE SCOPE:
After observations it is been witnessed that gap grinding has a key role in chrome broken defect.
Gap grinding machine: After the chrome plating procedure one of the main operation is gap
grinding. This operation is very critical because of its contribution to the rejection of the ring.
Due to this reason this machine is always been a point of interest for many engineers working on
rejection reduction. Gap grinder is a computer controlled machine having a grinding wheel
which fits in between the ring gap and grind it. A no. of ring are stacked and hanged in a T
shaped bar. An arm is provided to release single or a set of rings at a time. Ring is then grinded
at the gap with heavy supply of coolant in order to reduce chrome broken. Single ring or set of
rings are machined at a time according to the axial height of the ring. After the machining the
ring is then pushed through the sleeve and collected at the other end of the machine.
Tooling detail: -
1. Grinding wheel- 125x1.5x22.23 mm
2. Grinding wheel designation- CB200R100BK8
3. Grinding wheel material- CBN (Cubic boron nitride)
4. Grinding wheel R.P.M.- 6000±200 rpm
5. Coolant- CIMSTAR (4-6 % min)
No. of rings per stroke Axial height
4 Up to 1.7 mm
3 1.7< B <2.5
2 2.5< =B <6
1 6< = B & Above
Defects occurred-
1. ID gap broken- Gap is broken at the inner surface
2. Slant gap- Gap cut is not proper
4. OD scratch- Scratch at the outer surface
During the ring is inside the sleeve the grinding operation initiates and grind the ring. After this
the ring is pushed by a pusher, while pushing the ring leans backward and the gap is regrinded
and chrome is broken at the gap. Another problem arose due to the sudden expansion of the ring.

When the ring is pushed outside the sleeve, ring in closed position is freed and ring expands.
This sudden expansion lead to chrome broken. Final problem which is been the most critical one
is the chrome broken at gap due to impact of the fall from upper T- shaped slide to lower T-
shaped slide.
11.1 SUGGESTION OF IMPROVEMENT:
 Rubber support underneath the sleeve for preventing the ring from leaning backward
 Welding a slope joint between upper T-slide to lower T-slide to supress the impact of fall
- Rubber support underneath the sleeve for preventing the ring from leaning backward-
Gap grinding operation starts with the stacking of the ring at the input area. These stacked
rings are released one by one through an automated arm actuating system. According to
diameter of the ring 2 or more rings are machined in a single cycle. After these set of
rings are released from the stack a jet stream of coolant is directed on these rings to wash
of the gap area and to tightly organise it. These rings are then pushed into the sleeve
through a pusher. Pusher diameter is slightly less than the sleeve diameter such that the
pusher fits exactly into the sleeve. Ring is then grinded inside the sleeve and then pushed
further by the pusher. During this pushing action the ring leans slightly backward. This
lean cause the ring to regrind when the ring touches the grinding wheel. This effect
caused the chrome broken defect at the gap. The reason for this failure was analysed and
came to a conclusion. The reason is the looseness of the sleeve which caused the free
movement in the ring and due to self-weight it lean backward. To overcome this failure a
rubber attachment is suggested to recover this loss. The logic behind this attachment is to
add more grip and tighten the loose joint between the ring and the sleeve. The rubber
attachment size may vary with different sleeve size. This suggestion might be
experimented for better results.
Figure 13 Diagram showing rubber attachment in the sleeve bottom: SIDE VIEW

- Welding a slope joint between upper T-slide to lower T-slide to supress the impact of fall-
After the machining operation the rings are then pushed out from the sleeve. Then the
fully machined rings are collected at the ring collector slide. Before reaching the ring
collector the ring has to follow a bumpy path. As shown is the figure above the rings has
to follow the path of upper T-Slide and the lower T-slide by finally reaching the end
portion i.e., ring collector slide. The upper T-Slide is an inverted T shaped stainless steel
rod designed such that it can accommodate rings. The ring gap fits into the inverted T-
shape with the lower flat portion bearing the ring. These T-rods are given a slight slope in
order to slide the ring in its path. When the ring passes from Upper T-slide to lower T-
slide it has to fall from a height of 3-4 cm. This fall creates an impact force on the ring
gap. The effect of impact leads to breakage of the chrome coating at the gap. Chrome
broken is the major drawback in the production of CPC ring. The chrome broken defect
at the gap grinding machine is quiet enlarged as in this machine once machining is done
and if there is any defect it has to be rejects. While in case of honing operation if
rehoning occurs the lapping time is increased to recover the defect. The solution for the
defect caused due to the fall can be recovered by welding a slide attachment to the upper
T-slide. The logic behind this suggestion is to allow a smooth path without any impact to
the ring. The ring will slides effortlessly from upper T-slide to the lower T-slide with no
impact which leads to chrome broken. The upper T-slide is adjustable to accommodate
grinding wheel adjustment. Due to this reason the slide attachment is to be welded to the
upper portion only by making the upper T-slide detachable.
Figure 15 Diagram showing the two T-Slide of the gap grinding machine Figure 14 Diagram of the concept of slide attachment

12. CONCLUSION:
Methodology for rejection reduction was successfully submitted to my industry guide and
discussed about the outcome. In near future the new suggestion might be implemented if
successfully experimented. I feel proud in rendering my service to SHRIRAM PISTONS AND
RINGS LTD.
The internship gave me an opportunity to get a hands on experience of shop floor and the
required engineering problem solving techniques. Granted a chance to visit the complete
manufacturing line, I now understand the mechanisms concerned to the industry and my
curriculum. Being in the C2D1 ring manufacturing plant I gained an opportunity to closely
observe the working and management of manufacturing operations along with the live hurdles
and their solutions. After viewing the world class manufacturing process by myself, I feel
honored to get associated with such a well renowned company and with such a hard working
team.
13. REFERENCE:
Website:
www.shrirampistons.com
Books:
Company catalogue book

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