Practice English Speaking&Listening with: Lec 1 : Introduction

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Dear viewers, welcome to my course on introduction to machining and machining fluids and myself

Doctor Mamilla Ravishankar; assistant professor at IIT, Guwahati in the department of mechanical

engineering. Welcome to my course, In this class, I am going to start about what is the

syllabus of this course why we have to study this course and all those things ok.

So, that first why we have study this course on manufacturing is the one thing. So, the

one of the primary courses in manufacturing is machining and machining fluids also plays

a major role. That is why we are going to study in this course on machining and machining

fluids. So, if you see a manufacturing plays a very major role in any countries GDP. So,

as a developing nation India if at all want to move ahead. So, their manufacturing has

to be improvable a lot . If you see the many companies like Honda,

GE and all those these are companies are the one of the good companies in the manufacturing

arena and they are expanding their bases in India because they play a major role in manufacturing

ok. So, if you see in this slide, you can see the temple pillars also developed based

on machined components if you see the pillars these are all machined using the machining

process ok. So, coming to the syllabus we are going to

see; what is the syllabus of introduction to machining and machining fluids? So, the

overview of this course chapter one to eight we have complete chapters. So, the chapter

one a introduction to machining one b principles of machining or metal cutting.

So, coming to the chapter 2, we have the cutting tools and cutting forces chapter 3, we have

Tribology and surface roughness in machining thermal aspects in machining. So, chapter

4 deals with tool wear and tool life tool material and tool coatings. So, chapter 5,

we deal with cutting fluids and its application eco friendly cutting fluids and chapter 6

deals with multi points machining process where which is called as the practical machining

processes. Chapter 7, we deal with abrasive machining

processes and chapter eight we deal with machining of advance materials and machining advances

in machining processes ok. So, this is the overview; however, I am going to explain you

in detail what I am going to teach. So, in the chapter 1 introduction to machining.

We are going to see the importance of manufacturing why the manufacturing is important or for

a mechanical engineer at the same time; why the manufacturing is important for a country

and all those things. The second we deal with the basic approaches

in manufacturing there are 2 approaches one is top down approach and bottom up approach

in the manufacturing; however, we are going to study mostly top down approach where we

take the solid stock and we do the machining process to the required shape.

So, we do not touch the bottom up approach; however, we give some introduction to the

bottom of approach like 3 d printings and all those things the importance of machining

and machining fluids. So, in the manufacturing we have to see; what is the major role of

machining and machining fluids as per the course is concerned.

Why the machining is important for manufacturing why machining fluids are important what are

the problems with the cutting fluid and how we have to make the machining process a sustainable

process which is what the nowadays world is looking at .

So, then we goes to then we go to introduction to machining what is the machine tool and

what is the cutting tool what are the difference between a machine tool and a cutting tool

and all those things the overview of various machining process we we do .

Then we go to the 1 b where principles of metal cutting or machining we deal with. So,

mechanism of plastic deformation. So, normally machining process is considered as the severe

plastic deformation process if you see the stress strain diagram the machining starts

from this position. So, the machine machining starts after the severe plastic deformation

the fracture starts from there the machining starts.

So, the mechanics machining of ductile materials which is shown in this a stress strain diagram;

so, the machining starts from this position . So, the machining of brittle materials where

the stress strain graph will be slightly different which we deal when we are going to into the

complete ah in detail to the course. Then introduction to machining region what

is the machining regional what are the zones what are the shearing zone chip tool interface

and all those things what is the sticking zone what are the sliding zone sticking zone

refers to were the metal metal interaction is there and in sliding zone the chip moves

and abrades . Those who we also deal with chip formation

and types what are the different types of chips forming and all those things and we

also measured practically and theoretically we also deal with the ah chip thickness measurement

direct method and indirect method . So, in the chapter 2 we dual we deal with

the tool geometry and tool signatures in the tool signatures we deal with American standard

system that is ASA system ORS system, MRS system and NRS system , some of the systems,

I will teach you and some the systems I may give some assignment also. So, that you can

also learn in a good way the selection of ah tool angles what ah how to select the rake

angle what is the importance if I select more rake angle less rake angle and all those things

flank angles and the cutting edge angles if at all I want to choose for particular operation.

So, how to choose you can see in this picture what are the ah angles what are the surfaces

what are the vary the cutting edges and all those things . So, chapter 2 b deals with

cutting forces normally types of cutting there are 2 types of cutting one is orthogonal cutting

and oblique cutting. So, mostly we deal in this course is ah orthogonal

because this is a introductory course the orthogonal cutting we also see the forced

relationships shear angle relationship determination of coefficient of friction the coefficient

of friction is most important thing I mean to say is one of the most important thing.

Because what are the frictional losses and what is the useful energy what is the ah energy

that is wasted in the process and all those things determination of stress strain and

strain rate also we do measurement of shear angels comparison with the experiments and

some of the empirical models also we see . So, uh continuing to this cutting forces we

also see introduction to oblique cutting we do not go in deep to the oblique cutting we

do ah partially what is ah oblique cutting and all those things measurement of cutting

forces axial. So, in the measurement of cutting forces we see how to measure experimentally

the cutting forces like ah axially loaded member cantilever member's rings and all those

things. Some of the things I will explain some of

the things you may have to learn for for the assignments the dynamometer how the dynamometer

works what are the its requirements how it measure the forces machine tool dynamometers

and general remarks about it chapter 3 what we deal with is the Tribology and surface

roughness in machining. The tribology plays a very important role

in the chip tool region that is called a chip tool tribology tool work piece tribology and

types of lubrication there are 3 types of lubrication one is boundary lubrication mix

lubrication and hydrodynamic lubrication basically as a manufacturing engineer if at all you

see you require a hydrodynamic lubrication in the machining region.

But; however, you do not achieve it, but to achieve that one how and what we have to do

I will teach in this course the surface roughness the surface roughness how to get a good surface

roughness what is the problem in machining what is the roughness depend on on which input

parameters it mostly depends and all the things types of surface roughness determination of

surface roughness in the machining normally if your r a is proportional to f square by

eight r and all those relationships I will teach you the material removal and material

removal rate the machine ability of materials the ease of machining is nothing, but the

machine ability. So, how to machine different materials in

the chapter 3 b we deal with the thermal aspects of machining you can see in the picture how

the thermal aspects are determining the tool temperatures and the chip temperatures and

all those things. The cutting temperature if you see the temperature

distribution machining shear plane and chip tool interface normally chip tool interface

carries ah highest temperature . So, heat transfer in machining. So, heat transfer means

there is a temperature distribution and heat transfer to the 3 components that is the chip

tool and the work piece how the heat is transferred and the measurement of this temperature tool

work thermocouple technique infrared and the other techniques also we will see and we also

see some of the ah advanced things that is called metallurgical changes due to temperature,

normally, what are the metallurgical changes that takes place on the surface of the work

piece . So, chapter 4, normally, we deal with the

tool wear and tool life. So, what are the tool wear mechanism there are commonly said

mechanism are 3 one is adhesion abrasion and diffusion .

So, what are the types of tool wear lucky you normally at the basic level we teach the

flank wear and crater wear; however, there are many wear like notch wear cutting edge

wear and all those things we may touch those also the tool life. So, there are many criterias

of tool lives. So, some of the criterias, we deal with where

various variables affecting the tool life what are the input conditions affect what

the tool materials that affect and all those things there are tool life equation normally

there are 2 commonly used equations one is Taylor tool life equation another one is modified

Taylor tool life equation . So, chapter 4, we also deal with tool materials

and tool coatings in order to improve the tool life. So, what are the tool materials

available that is high speed steel uncoated carbide and coated carbide ceramics cermets

CBN and diamond not only this we also deal with some of the coating materials on the

tools to improve the ah machine ability there are many varieties; however, we deal with

2 types of coating one is soft coatings another one hard coatings soft coatings provide better

lubrication and all those things hard coatings provide ah better tool life.

So, the coating techniques also we deal with what PVD physical vapor deposition chemical

vapor deposition radio frequency sputtering laser coating and this are the things we see

at the same time we also see the tool texturing in order to improve the ah tool chip interface

Tribology, we do the some of the nano texturing micro texturing.

So, that also we deal how this will improve the tool life .

So, in the chapter 5, we deal with cutting fluids and the application as our course if

you see it is the introduction to machining and machining fluids. So, machining fluids

normally are the cutting fluids. So, this chapter also plays a very important role where

you learn mostly about the cutting fluid basics as well as some of the advances in the cutting

fluids like cutting fluids classification based on lubrication criteria based on ah

cooling criteria and all those things. What are the functions of the cutting fluids

types of cutting fluids if you see the types of cutting fluids cutting fluid additives

there are many additives ah which improve the performance of cutting fluids like ah

biocides emulsifier rust inhibiters and all things at the same time this are mechanically

very important, but if you see the environmentally they are slightly adverse effective.

So, they causes some of the problems to the operator and all those things. So, how to

find a some optimum solution and all those things we will study in this chapter emission

and health hazards Rheology of the cutting fluids normally the Rheology is nothing, but

the signs of flown deformation. In this case, since the cutting fluid is a

liquid normally what is the ah thing that we study is the flow properties. So, if you

know the better flow properties of the cutting fluid if we can design a cutting fluid with

better flow properties what will happen the flow ability will increase to the intricate

regions of the chip tool interface and the flank surface and work piece interface.

So, that it will improve the tool life at the same time will give the better surface

roughness. So, the rheology aspects also we will study we study the biodegradability because

after the multiple utilization of this cutting fluid if we dump into the a nearby water bodies

or the soil bodies it will deteriorate the that eco system depend on the whether you

are dumping into the water or whether you are dumping into the ah soil it will destroy

I cannot say completely destroy it will have its own impact on that one ok .

So, the cutting fluid applications if we see the cutting fluid application normally you

can apply flood cooling minimum quantity lubrication high pressure there are many varieties of

application techniques are there at the same time this application techniques will vary

depend on their standard of distance from machining region angle of impingement whether

you are putting 45 degrees whether you are putting ninety degrees or whether you are

putting 60 degrees and all those things it will vary.

If at all I want to send to the chip tool interface at what angle if I send and. So,

that it will have the maximum affect that all things we will study . So, area of cooling

if at all I am increasing the standard of distance what will happen my area of covering

will be ; obviously, increases. But the scene I want is a optimum area. So,

for that purpose what will be my standard of distance if my standard of distance is

less. So, it can cover only less area if my standard of distance is more. So, my covering

area will be more, but I have to design my standard of distance so that my area of cooling

will be the machining region. So, once I calculate or experimentally measure

my area of machining depend on that I can play with these input parameters like standard

of distance angle of impingement so that the area of cooling and lubrication will be proper

. So, as you know the ah cutting fluid application

techniques there are different techniques that I have already told you that MQL and

high pressure techniques and all those things . So, chapter 5 b, we deal with some of the

echo friendly cutting fluids how to develop the echo friendly cutting fluids.

So, bio degradation of cutting fluid how to do the bio degradation so that the chemical

oxygen demand biological oxygen demand, what is this chemical oxygen demand what is this

biological oxygen demand what is a hydraulic retention time effect of cutting fluid on

operator see; that means, that what are the effect of the cutting fluids on operator .

What is its causes if it is enters into the nose what will happen if it a falls on a skin

what will happen; these are the things we will study the effect of cutting fluid on

the environment c it will causes how it causes various adverse effect to the environment

water pollution soil pollution and all these things, we study.

So, chapter 6, we deal with multipoint machining processes which is also some of the text books

call it as practical machining processes . So, we do the study about introduction to multi

point machining processes . So, we ah start with milling process introduction to milling

what is undeformed chip thickness forces how the better surface finish is achieved in this

milling process. Then we go to the introduction to the drilling process and we see its slightly

the introduction mechanism of that one and mechanics of that one forces surface finish

undeformed chip thickness . So, we also study about the tapping process

how to make internal and external threads on it using the tapping process the broaching

is another ah process where if at all we want to do for the high aspect ratio applications.

Sawing if at all you want to do the parting operations we can use a sawing operation and

gear cutting operation how to do the gear cutting operation and all those things. In

the chapter 7, we see abrasive machining processes it comes under the multipoint cutting tool,

but it is one of the abrasive processes basically ok.

So, the grinding process is one of the abrasive processes where we study about the wheel specification

how to design the grinding wheel classification thermal aspect of grinding we and the conventional

finishing process ah like lapping honing what are the effects of ah this processes on the

surface finish of the product. Lapping gives very better surface honing gives

not only the surface finish it also gives such crochet patterns how it will generate

this generation is due to the reciprocation and rotary motions of the tool, what is intra

ah what is super finishing operation drag finishing vibratory finishing these are all

the finishing processes that are commonly used for the bio implants. So, at the end

of this course you should also see the practicality of the process and practicality of this course

you should appreciate the course whenever you see ok we have studied the basics now

we have to apply for this mechanism to the advanced applications.

So, we also see the obligations ok chapter 8, it is.

Completely introduction to the advances in metal cutting operations like hard machining

what is hard machining till now, we have studied normal machining what is hard machining whenever

you are we are machining the hard materials normally the HRC that is Rockwell hardness

value is above 54 or 55 not only that it will depend your ah input parameters also.

So, normally it will depend on the ah work piece hardness basically. So, high speed machining

whenever you are working or whenever you are operating the up this machining process at

very high speeds. So, ah in terms of milling it is tool rotation in terms of turning it

is work piece rotation. So, they based on the rotary element this

will decide diamond turning diamond turning normally it comes under the one of the finishing

processes , but it is one of the advances in machining process vibration assisted machining

normally vibrations are provided to the tool so that ah it will enhance machine ability

. Machining with rotary tools thin wall machining

thin wall machining also plays a important in aerospace applications laser assisted machining

normally laser assisted machining is one of the advance processes because if at all I

want to machine a brittle material. Normally the in the conventional machining

process if you see if I want to machine a brittle material with ah tool normally in

a conventional machining the tool is much much harder than work piece. So, what will

happen there is chance of brittle fracture in order to avoid that what is ah what the

researchers do is just they pass the laser on the work piece surface ahead of the tool.

So, that it will partially soften the work piece; that means, we are converting the brittle

material into ductile regime or ductile mode then we are doing the machining operation

with the conventional cutting tools that is nothing, but ductile regime machining of brittle

materials. So, indirectly what we are doing is we are

converting the brittle material into the ductile mode then we are machining it that is called

laser assisted machining process then we also look for the cutting fluids what are the advance

cutting fluids that are used in high speed machining hard machining and machining of

advance material like like high speed machining .

The basic ah drawback of high speed machining is temperature will be very high how to overcome

this one. So, you need to choose the cutting fluids whose cooling ability is higher there

our cooling ability is most important factor rather than lubrication in hard machining

operation lubrication should be higher cooling can be lower only thing is that it cannot

be 0, but the thing is that how to optimize both the things that is what I mean ok.

So, see we also study about machining of advance materials some of the advance materials as

per now is concerned biomaterials. So, if at all I want to machine this me implant materials,

how I have to do it because whenever if I do the temperature is very high and if I am

using very hard tools what will happen if the temperature is very high, this surface

what will happen is metallurgical changes which hampers the operators health when after

some time of the implant inside. So, in order to prevent all these things we

have to take care of this material when the machining operation is going on the aerospace

materials titanium alloys it is very difficult to machine the titanium alloys because the

heat transferring heat dissipation ability of that material is low.

Whenever you are doing the machining operation the temperature stays mostly on the surface

which will impart to the tools. So, the thermal softening of tool takes place and the tool

life will goes down. So, we have to take some precautions while machining the airspace materials

. Machining of smart materials we do machining

of the electronic materials and machining of polymers and composites. So, we also deal

with machining of slightly composites when because the composites contains the reinforcement

as well as matrix. So, whenever it is the tool is touching reinforcement what is the

physics whenever it is touching the matrix what is the physics all these things we study

ok. So, ah that is all about my course introduction

and ah thank you for registering for my course and from next class onwards we deal each and

everything in detail in the course introduction to machining and machining fluids.

Thank you .

The Description of Lec 1 : Introduction