INTERNSHIP ON “MANUFACTURING & CALIBRATION

OF FUEL INJECTION PUMP (PF-51) & ENGINEERING OF SPECIAL PURPOSE

MACHINE”

ADITHYA L VIMS11ME225

Completed at

Bosch Ltd.,Hosur Road, Adugodi, Bangalore - 560030.

COMPANY PROFILE The company was set up in Stuttgart in 1886 by Robert Bosch

(1861-1942) as “Workshop for Precision Mechanics and Electrical Engineering.”

Robert Bosch is the world's largest supplier of automobile components and has business relationships with virtually every automobile company in the world.

Bosch invented the anti-lock braking system (ABS), and is a leader in specialized fields as traction control systems (TCS), the Electronic Stability Programme (ESP), body electronics (such as central locking, doors, windows and seats).Bosch is a leading player in car stereo systems and in-car navigation systems, which is sold under the Blaupunkt brand name.

The Bosch Group operates in India through six companies, viz, Bosch Limited, Bosch Chassis Systems India Limited, Bosch Rexroth India Limited, Robert Bosch Engineering and Business Solutions Limited, Bosch Automotive Electronics India Pvt Ltd, Bosch Electrical Drives India Pvt Ltd.

Bosch has been present in India for more than 80 years - first through a representative office in Calcutta since 1922, and from 1951 through its subsidiary Bosch Limited. Bosch Ltd was initially incorporated as Motor Industries Company Ltd. (MICO) on November 12, 1951, with its head office then located in Chennai.

MICO is a very strong brand name in the Indian automotive industry. MICO has been renamed Bosch Ltd. Today the Bosch Group in India has grown to include 6 group companies of which Bosch Limited is the flagship business entity.

Headquartered out of Bangalore, Bosch Limited has its manufacturing facilities in Bangalore, Nashik, Naganathapur, Jaipur and Goa. These Plants are TS 16949 and ISO 14004 certified.

Bosch Limited manufactures and trades in three of the major business sectors of Bosch, namely;

Automotive TechnologyCommon Rail System for all vehiclesInjectors and injection nozzlesInjection pumpsSpark plugsIndustrial TechnologySemi/fully automatic assembly linesSemi/fully automatic inspection and measuring instrumentsTools, gauges and fixtures Consumer Goods And Building TechnologyPneumatic toolsMetal working toolsVideo Products and Systems (IP & Analogue based CCTV System)Fire Alarm SystemsHome appliances

PA-ATMO PA-ATMO(Assembly Systems and Special Machinery) is the

internationally leading internal special machine-builder, technology and service partner for all Bosch divisions.

In nine locations world-wide ATMO develops new innovative solutions and guarantees the technological innovations and advanced development.

As an internal supplier ATMO belongs to the Bosch and contributes effectively to the know-how protection. On demand, ATMO sets Bosch desired standards on the external market.

The Indian office of this group is located in Bangalore, India and is addressed as PA-ATMO6.

NATURE OF WORK The internship at Bosch Limited was carried out in two varied

departments over the period of 6 weeks dated from 11.06.2014 to 23.07.2014 .

During my first 4 weeks, I was assigned to pressure pumps (PF - 51) for common rail injection systems in the production sector of BOSCH Ltd.

I observed the processes in the pump manufacturing that involved casting, durr cleaning, heat treatment and so on. I also observed the assembly of pressure pump.

Mr. Shiva Kumar was the internship guide in the production plant. He encouraged me to learn the processes involved in pump manufacturing and quizzed me on regular basis on various processes learnt on shop floor.

I was also assigned the task of comparing the guidelines set for the workers and guidelines followed by workers during various processes in pump manufacturing.

For the following 2 weeks, I was given the opportunity to work at PA-ATMO6 (Assembly Systems and Special machinery) division.

A special purpose machine named ‘Pin pressing station’, designed for the fabrication torsion bar of steering columns for FORD automobiles was the project assigned by my mentor Mr. Sharath M S as my first task. I was assigned to observe the processes performed by the machine and help the workers in the fabrication of the machine.

I performed tasks such as measurement using slip gauges, setup of pneumatic pipe lines in the machine, drafting and so on.

I was also given the opportunity to observe the fabrication and functioning of a state of the art conveyer machine built for a specific BOSCH plant in Germany.

During the tail end of my duration at BOSCH, I was given the opportunity to visit RBAI plant at Naganathapura, Bangalore.

CURRENT SYSTEM LAYOUT OF COMMON RAIL

PF 51

PRESSURE PUMPS Many engines (older motorcycle engines in particular) do not

require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine. But in non-gravity feed designs, fuel has to be pumped from the fuel tank to the engine and delivered under low pressure to the carburetor or under high pressure to the fuel injection system.

Bosch is a worldwide leader in Diesel Fuel Injection technology for over a century

Pressure pumps are used for fuel injection system for diesel engines. The main function of the pressure pumps is to supply diesel at high pressure range depending on the vehicle. The pressure pump consists of 2 main components namely the barrel and the plunger.

Bosch mainly produces three types of pressure pumps. They are:Monoblock Type (PF)Q Type (PFE)K Type (PFR)

The Monoblock type also called as PF Pump is further classified into 2 types depending the application. They are:

PF-45PF-45 pumps are used in heavy load vehicles like trucks, buses and

tractors.The major customers for PF-45 are Volvo, Mahindra, Tata and so on.PF-45 pumps have 2 variants, the 1200 bar pump and the 1600 bar

pump. PF-51PF -51 pumps are mainly used in passenger cars. The major customers for this model are Tata, Volvo, Honda, Suzuki

and so on in India. PF-51 pumps have three variants, the 1100 bar pump, 1450 bar

pump and 1600 bar pump. Depending on the vehicle, suitable pump is selected.

PF – 51 PRESSURE PUMPThe block diagram shows the components

of a PF-51 pump when it’s assembled. The components can be divided into 2 sections, namely the plunger section and the barrel section.

Thus this entire unit is installed in the common rail system to convert low pressure fuel into high pressure fuel at 1600 bar OR 1450 bar.

The PF – 51 pressure pump is the most popular of all the pressure pumps produced at BOSCH as its widely used is cars such as Suzuki Swift, Suzuki Dzire, Tata Indica, Tata Indigo, Fiat Punto and so on.

The production of PF – 51 is studied in 3 parts, namely the barrel process, plunger process and assembly& testing.

WORKING OF PF – 51 PUMP The diesel fuel enters into the pump through inlet connector. The fuel

thus enters into plunger top region inside the barrel through a hole (barrel port).

Some part of the fuel goes through cross hole which helps in lubrication. Finally excess fuel comes out through the overflow connector and goes

back into the fuel filler. When the driving cam rotates from BDC towards TDC, the bottom spring

plate also moves pushing the plunger up. Once plunger top end closes inlet hole of the barrel, the oil above the plunger gets pressurized.

This high pressure oil further moves up and opens a central pin in the non-return delivery valve. The fuel thus flows up and comes out of the pump through the DV holder.

A high pressure pipe connecting the pump and to an injector that is fitted on the engine. Thus the low pressure oil is converted to high pressure (1600 bar) by PF – 51 pump and is injected to the engine.

BARREL PROCESS

• Pre Honing

• Finish Honing

• Deburring

• Main Bore Brushing & Boroscope Checking

• DV Seat Grinding

• Spirit Cleaning & Visual Inspection

• Technoscope Inspection

• For Selective Assembly

IMPORTANT PROCESSES OBSERVED HONING

Honing is a machining process where the honing tool removes metal to the required size from the given barrel. It’s metal removal process where precision surface on metal work piece is obtained by using an abrasive stone or tool against it along controlled path.

It was performed in 2 stages, namely Pre-honing and Finish honing. As the names suggest, rough or approximate dimensions obtained from stage 1 and fine finish to the required specifications are obtained from the stage 2.

The machine used was Gehring. DEBURRINGDeburring is a finishing process performed to remove chips, blockages and

rough surfaces in the barrel bore. The barrel contains tiny holes in it through which the fuel flows and the

pressure is increased to about 1100 bar to 1600 bar. Blockage of these paths may lead to pressure build up and eventually failure.

Pneumatic gun with deburring tool in the form of stick made of ‘Carbon Boron Nitride’ called the CBN stick was used.

MAIN BORE BRUSHING & BOROSCOPE INSPECTIONIn main bore brushing, the debris in the main bore are cleared using

special brush made up of nylon that is of the hardest type. Here the rough surfaces, lines or indentations and burrs are removes and thus ensuring that the main bore is free from all imperfections.

Boroscope inspection is a visual inspection station that is similar to endoscopy where magnification camera (15 X magnification) is used to check for burrs and roundness of the holes as mentioned in deburringThe worker carefully examines all the holes and the computer measures the roundness of holes using sophisticated software.

DV SEAT GRINDINGDelivery valve (DV) seat grinding is a critical process in the

production of the pump. The DV is the main component through which the fuel enters and exits at high pressure. Hence the seating of the DV holder must be absolutely perfect without any imperfections.

The DV seat grinding is performed in PMT machine and the grinding wheel is an abrasive wheel of highest quality.

PLUNGER PROCESS • Heat treatment

• Shot Blasting

• Durr Cleaning

• Pre grinding

• OD Finish Size Grinding

• Oiling Inspection

• C1 Coating

• Plunger Size Grouping

• For Selective Assembly

IMPORTANT PROCESSES OBSERVED

SHOT BLASTINGShot blasting is a surface cleaning process where there is removal of

scaling on shaft, centre hole and grooves using special abrasive materials. The shot blasting process is performed in the Studer machine.

DURR CLEANINGThe durr cleaning machine is a powerful spray flood cleaning system

with a vacuum-tight work chamber. The main purpose of using this machine is that in the manufacturing of the pump, different types of oils, solvents, lubricants, chemical agents and so on are used. These need to be thoroughly removed for the assembly of the pump. Hence this industrial washing machine is used at BOSCH.

PRE GRINDING Similar to the barrel process, the plunger must also be free from chips and other residues. Hence the plunger is reduced to required diameter. The pre grinding is performed in the ‘Parishudh’ grinding machine that is used specifically to grind rods of small diameter.

SELECTIVE ASSEMBLYThis is stage in which the suitable plunger is selected for a respective barrel. This is the most important stage of the pump manufacturing that determines the quality of pump and its functioning. If a particular plunger is too small, then the computer suggests a different plunger and this process repeats until the best plunger is matched with the barrel and there by completing the selective assembly.The selective assembly process is as follows:

• The plungers are sorted and grouped according to their size.

• The barrel is placed in the measuring equipment that determines the size of plunger to be selected and also provides tolerance limits.

• The worker selects a plunger according to specified size and inserts into the barrel.

• The worker checks the measurements at 3 locations since the plunger is slightly tapered.

• When all 3 measurements fall in the tolerance limit, the computer gives a green light. However if anyone measurement fails, the plunger is removed and a different plunger is tested.

ASSEMBLY & TESTING • Durr Cleaning

• DVH Sub Assembly & Pre Tightening

• Compression Springs & BSP Assembly

• Connector Assembly

• Leak Testing

• Static Flushing

• Functional Testing

• Visual Inspection

• Packing

• To store

The diagram shown provides the assembly sequence of the Delivery Valve Holder (DVH) sub-assembly.

This stage is followed by complete assembly and sent for various testing.

Some of the test performed are:-o LEAK TESTINGo STATIC FLUSHING o FUNCTIONAL TESTINGo VISUAL INSPECTION

Once cleared of all tests, it is sent to systematic packing and forwarded to delivery to various customers.

Important Processes Observed

LEAK TESTINGAfter the complete assembly of the pump it has to be tested to see whether all the components are fitted properly. This is done at the leak testing station. A special pneumatic system is used for testing.

The overflow connector and the inlet connector are fitted with the pipes from the pneumatic system.

Air at high pressure of 200 kPa is supplied into the pump.

The barrel is said to be assembled corrected if a pressure of 400 kPa is built up in the pump with in a prescribed time. If pressure is not built up suitable actions are taken.

STATIC FLUSHING During the processing of barrel or during the assembly of the pump, the pump

might have residues such as chips, debris and so on. These need to be removed before the pump is used or else the pump might not function in the optimal level.

The flushing is done using a special type of fluid called ‘SRS Calibration fluid’.

OBSERVATIONS FOR IMPROVEMENT

PRE HONING

• The barrel main bore needs to be measured before it’s placed in the machine. However the workers failed to do so. They omitted this important step of pre measuring.

• The taper limit ranges from 165 to 180 microns. However the taper achieved was about 187 microns. Hence the machine was not performing at its optimal level and calibration was required.

FINISH HONING

• The honing machine needs to be calibrated after every 20 pieces of machining to ensure that the accuracy is maintained. However this critical step was omitted by the workers.

DEBURRING

• The specified number of strokes to be performed for deburring is 4 -5 strokes. However the workers performed only 1 – 2 strokes.

• After the deburring process, the holes need to be checked for roundness and to identify burrs using boroscope inspection. This major process was not performed over 3 weeks since the device was not working.

PIN PRESSING STATION(STN 160) STN 160 was a special purpose Assembly unit that was used to

fabricate torsion bars for the steering column for FORD. The unit was a rotary base assembly unit which was divided into

multiple stages to perform tasks simultaneously and thus improve its production efficiency.

The unit is a majorly pneumatic controlled assembly. I was given the opportunity to study the pneumatic systems and layout implemented in the unit.

Overall cycle time on this machine is 57 seconds.

Drilling & Pin Pressing

Chamfering

Axial & Radial Unloading

Alignment

Loading

Processes of Pin Pressing Machine

NOTABLE FEATURES LOADING STATION Utilization of various equipments such as :-1. Air pressure switch or a Vacuum pressure switch- pressure switch

to ensure that the component is placed properly in the fixture. 2. Keyence sensor- an optical sensor that is used to ensure

complete butting3. Cognex camera- camera used to read the component bar code

reading

Also POKA YOKE was implemented in the fixture. 

AXIAL AND RADIAL ALIGNMENT STATION At this station, the 2 components to be pressed need to be aligned. This stage uses a servo motor and an encoder to perform the task of alignment.

2 major features in this station were :-1. The component after loading moves and the component is held by

hydraulic jaws controlled by a servo motor. 2. Use of an encoder to calibrate the servo motor position was an

important feature of this station.3. Also use of friction clutch to adjust the force exerted by the servomotor

during alignmentDRILLING AND CHAMFERING STATION Important aspects in this station were:-1. Spring activated clamping jaw controlled by a proximity sensor used to

hold the component in position 2. Chips generated are removed by a chip extraction unit working on

vaccum.3. Shock absorber or damper to dissipate the excess vibrations.

PIN PRESSING STATION1. Single most important feature in this station was the pin

pressing servo motor. The servo motor had an sensor is inbuilt. 2. This sensor measure the diameter and length of hole. Depending

on the size of the hole, the best pin size is determined. 3. Based on the measurements taken, the machine actuates the

door of required pin (6 sizes available).

OTHER ASPECTS LEARNTApart from the engineering aspects deployed behind the working this

assembly line I also learnt the importance of various other non-engineering aspects like:-

Safety - is an essential criterion in any machine or product. Safety switches are used on all doors to ensure safety of operator. The machine would fail to start or cease to operate if the doors are open.

Color Coding - Color coded light indicators are used to notify the operator or the production line of various conditions like Break down, running, auto mode, etc. by just viewing the color of light.

Quality - During this case study period, I was allowed to help the employees in quality checking and analysis, i.e. measurement of various components of the machine and seeing if they lie within the tolerance limits.

OTHER TASKS PERFORMED Superficial study of Conveyor Unit Selection and installations on washers throughout the machine.

Engineering Drawing and drafting This task helped me strengthen my skills and learn few important

ones such as :-

better drafting and designing skills of engineering drawing. Geometric dimensioning and tolerancing (GD&T)

SUPPLIERS FOR BOSCHApart from in-plant training, I was also allowed to accompany employees during their visits to suppliers to whom BOSCH had ordered for specific components or services.

This helped me understand the out sourcing concept. I was given an insight as to how the whole process works.

I visited 2 factories, one in Peenya 1st called ‘Precision Techniques’ and other one in Peenya 2nd stage called ‘Simtrix Systems’.

BENEFITS FROM THE INTERNSHIP Understanding of application of Pressure Pumps in automobile systems.

Exposure to the products manufactured by Bosch.

Insight to various machines used at Bosch for the multitude of processes.

In depth understanding of the PF-51 Pressure pumps and the common rail injection system.

Saving time is of paramount importance at Bosch. I was able to understand how to implement processes that take the least possible time.

I was able to suggest certain improvements in the PF-51 process

Fail-proofing goes a long way in saving time and I was able to learn management techniques such as Poka-yoke and Kanban

Better drafting and designing skills

I was fortunate enough to visit the suppliers for Bosch and gained insight regarding the out sourcing of work to reduce work load on the company and save time.

THANK YOU