L&T MHI TURBINE GENERATORS PRIVATE LTD.HAZIRA, SURAT.

SUMMER INTERNSHIP

BY PARTH K. GANDHIDURATION: 16TH JUNE TO 16TH JULY, 2014

INDUCTION The Production Shop is divided into six sub-divisions along with a Main Store. The six sub-divisions are four Machine Shops and two Fabrication Shops,

being listed from T1 to T4 and T5 to T6 respectively. Also there is High Speed Balancing Test Setup, Blade Manufacturing Shop,

Coil shop, Turbine and Generator Assembly. The various machines present in the production shop are capable of

executing a wide range of machining processes and have varying dimensional capabilities. There is a collection of some of the best machines available across the world, such as Pama, Skoda, Waldrich Coburg, Shweiss etc.

The Machine Shops have various machines for performing operations like turning, boring and milling.

The machines in the Machine Shops include Gantry Plano-Miller(Biggest Machine in INDIA), an Electric Discharge Machine (EDM), Vertical and Horizontal Turning Lathes, Vertical Turret Center, Horizontal Boring Machines, Rotor-Slotter Machine, a Side-Entry Groove Machine, and Radial Drilling Machines etc.

The Vertical Turret Centre is the machine in T4 shop where both, turning and milling, can be done.

In Fabrication shop, operations like welding, cutting, heat treatment, shot blasting, bending and packing are performed.

Major equipment in the Fabrication shop includes Heat Treatment Furnace, 20T Welding Positioner, Rolling Machine, Hydraulic Press, Plate Bending Machine, Packing Machine and Shot Blasting Booth.

INDUCTION TO ALL MACHINES OF T3 SHOP

After the induction of all shops, I was allocated to T3 shop where I studied all machines which are:

VERTICAL TURNING LATHE

HORIZONTAL BORING MACHINE

ELECTRO DISCHARGE MACHINE

PLANNO MILLER FOR MILLING OPERATION

DEBURRING AND CLEANING SECTION

MARKING TABLE

Project: Time Study and Evaluation of Machining Process

MENTOR: MR CHETAN PATIL (HEAD T3 SHOP)

DEPARTMENT:MACHINE SHOP, T3 IN PRODUCTION SHOP

MACHINE: VERTICAL PRECISION MILLING MACHINE, PM202

ASSOCIATE ENGINEERS: MR ANKUSH JAGGI & MR DEVAL DIXIT

OBJECT: HP PEDESTAL LOWER HALF

STEAM TURBINEBEARING PEDESTA

L

A steam turbine is a mechanical device that converts the heat energy of steam to mechanical energy. This mechanical energy, in the form of rotary motion of the turbine is particularly suited to drive an electrical generator.

In large power stations, the steam turbine is divided into three distinct power stages, the first being high pressure (HP), the second Intermediate pressure (IP) and the third low pressure(LP). Separate cylinders for IP and HP stage can be used or both the turbines can be housed in one casing and called HIP turbine.

Bearing pedestals are provided for supporting this turbine rotors at the two ends which enable them to rotate freely.

BEARING PEDESTAL

Bearing Pedestal performs the following functions: - It supports the rotor via journal bearing & maintaining gland clearances & also inter-

stage clearances.

It houses the lubricating & jacking oil supply piping & bearing oil drain pipe work.

Encloses various instrumentation connections. E.g. bearing temperature, speed measurement, differential expansion, electricity, vibration pick-up, etc.

It covers the rotor coupling.

Oil guard rings provided at the two ends of pedestals prevents the leakage of oil & vapors.

PROJECT OBJECTIVE To study all production parameters like drawing study, process

planning sheet, route card, preventive and predictive maintenance sheet as well as tooling sheet.

To analyze the all machining processes and their respective timings with standard timings given by MHI.

To note the wastage or leisure timings done on shop floor.

To enhance the efficiency of machine with possible adequate solutions for current industrial problems.

METHODOLOGY First of all I studied the PPS of HP PEDESTAL LOWER HALF and note the

basic standard timing for completion of object. Then the analysis of drawing, that exactly what it is and how the

machining operations are done on it, in what order, with what tolerances and which operation are difficult to process.

Then I observed the whole process done by operators on HP PEDESTAL LOWER HALF step by step and calculate amount of actual time required by them to complete the component.

Then we match the actual time with planned time and we found that the actual time was more than the planned time but not by a larger quantity except for two cases which are:

1. Roughing of Bottom Face.2. Machining of Oil Groove.

COMPARISON FOR LAST 3 PROJECTS

MH3 SR1 SR2050

100150200250300350

308.5286

239

SMH VS ACTUAL TIME

SMH =194.55

Y-AXIS: 1 UNIT = 1 HOURS

CASE STUDY ROUGHING OF BOTTOM FACE:

Planned time (By SMH) – 4 hours 18 minutes Theoretical program time – 5 hours 4 minutes Actual time – 11 hours 46 minutes

Problem Causes Corrective Action Extra Time Taken

2 extra passes had to be taken

Depth of cut chosen was 2mm less than the planned value because machining limits.

An extra 2 hours 32 minutes of machining had to be done to compensate.

2 hours 32 minutes

Use of extension head

Extension head installed could not operate at the desired cutting depth.

-  

2 extra passes had to be taken

Extra material of 5mm was present after fabrication process.

An extra 2 hours 32 minutes of machining had to be done to compensate.

2 hours 32 minutes

Insert wear out Inserts have to be replaced after every 1-2 passes. This replacement takes time.

Include an estimate of the time taken for this in the planning or select working ranges in which this would not happen.

 

Insert change For a tool with 16 inserts, up to 20 minutes per pass was used in replacing worn out inserts.

This time should be considered while calculating the approximate machining time.

1 hour 20 minutes

Offset had to be taken again

For every tool and insert change, the offset had to be taken again.

Extra time was taken to take the offset again.

40 minutes

Development of chips and coolant accumulation

Anytime material removal is done, metal chips are developed and have to be cleared. Cleaning both takes approx. 5 minutes per pass.

No corrective action possible. Necessary action to ensure correct finish and preventing the destruction/wear out of the inserts or cutting tools.

40 minutes

Different cutting speeds, feeds and depth of cut

Values prescribed in the PPS are difficult to match for reasons such as machine capability limits, material stress limits and the possibility of insert and tool wear out.

The timings mentioned in the PPS are as per theoretical calculations and the actual parameters and timings are different.

 

Machining of oil groove: Planned time (by SMH) – 2 hours 6 minutes Theoretical program time – 2 hours 34 minutes Actual time – 4 hours

Problems Causes Corrective Action

Extra Time Taken

Drilling done to generate slot

Drilling had to be done to set the starting point for further machining.

Extra time taken to drill the 6 holes should be added to the PPS as it is a part of machining time.

30 minutes

Time taken for setup Setting of the drilling tool and taking offset for the same took up extra time.

Can be added to the PPS as setup time for this operation.

10 minutes

Development of chips and coolant accumulation

Anytime material removal is done, metal chips are developed and have to be cleared. Cleaning both takes approx. 5 minutes per pass.

No corrective action possible. Necessary action to ensure correct finish and preventing the destruction/wear out of the inserts or cutting tools.

40 minutes

Different cutting speeds, feeds and depth of cut

Values prescribed in the PPS are difficult to match for reasons such as machine capability limits, material stress limits and the possibility of insert and tool wear out.

The timings mentioned in the PPS are as per theoretical calculations and the actual parameters and timings are different.

WHAT I LEARNT FROM MY TRAINING?

I got to know about different type of tools and inserts used for different processes. I also study the nomenclature and geometry of tools as well as inserts which are used for machining.

I came to know the basic process from operator by understanding loading condition, speed override, feed override, spindle override, rpm, reference machining, maximum rotation diameter, coolant condition, chip conveyor arrangement, jigs and fixtures, tooling parts, dial gauge for levelling and centering, measuring devices, inserts, jaws, blocks and clamps etc.

I got to know about the magnetic chuck used for clamping the component while it’s being machined.

I also learned how to calculate the approximate time taken by the machine to complete a specific process.

Here also I understood the Industrial Management terms like wise EHS (Environmental Health And Safety), 5 S, TBT (Tool Box Talk), HJS (Horizontal Joint Surface), Route card, NCR (Non Conformance Report), PPS (Process Planning Sheet), Tooling List, Preventive and Predictive Maintenance Check Sheet etc.

I also got to know about different process terms like spot facing, back spot facing, weld edge and dry run.

Also, I learnt the use of the Go-NoGo Gauge from my project mentor, who also taught me how to use the same while checking the threading performed internally in holes and bores on the machined surface.

I also learned to analyze the programs made for the different operations and how to interpret the various process parameters like depth of cut, cutting speed, feed given etc.

OBSERVATION

Clogging of chips around the tool and the component that is machined makes it difficult to do the process properly.

Excess use of coolant. It should be used within permissible limits as sometimes coolants goes in part of component where it is not required.

Many times tools of the machine are taken by other machine operators or by other shop which sometimes stops the machining of component which increases actual time of machining.

Leakage of air is observed in many machine and may be leading to losses. Also there is misuse of compressed air in the purposes where it is not required.

At many instances, the operators ran the various operations at speeds lesser than the prescribed values, resulting in the need for multiple passes and therefore, more time than what is listed in the Standard Man Hours for the operation.

Usually operators stops working during the last half hour of their shift and would spend the time idle. This time can be used up for other purposes or at the very least another pass can be completed in the idle time.

There is always a possibility of extra material being present on the component, which was also the case with the HP Pedestal, which had 5mm of extra material which took extra time to remove.

SUGGESTIONS For removing the chips during machining the workers used to

remove it by a steel rod which is dangerous and may also affect the surface finish of the component. For that there should be CHIP BREAKERS fitted with tool point, which will break the chips in discontinuous fashion, resulting in less clogging of chips around the component and between the job and the cutting edge of the tool.

A set no. of tools should be present at every machine for all basic purposes.

 

The usage of coolant should be regulated in a way to extend the usable life of the coolant. In many cases, multiple tubes or faucets delivering the coolant were switched on, some of which weren’t even aimed at the surface being machined, thereby causing major wastage of the coolant, which cannot be circulated permanently and has to be replaced after set periods of time. This can be implemented by properly observing and supervising the usage of coolant at the time of operation and then instructing the operators as to the proper use.

Leveling and Centering operation take almost half time of the whole machining operation, so it must be reduced anyway by proper skilled operators or by proper accurate clamping arrangement ex. Magnetic chuck.

THANK YOU