Structure of Matter (Bonding of Solids,Crystal Structures)

Structure of Matter (Bonding of Solids,Crystal Structures)


Welcome to this module 2 of Manufacturing
Systems Technology. Briefly review or recap of what we did in
the last lecture. We talked about some basic definitions of
manufacturing technology also worked on manufacturing systems approach. How a manufacturing system would work with
a core full of manufacturing processes. We talked about various consolidated models
of manufacturing enterprise how a different you know, wings of manufacturing enterprise
can function with customer centric approach; where these wings can intercommunicate and
also communicate with customers to have a good, you know the management of the whole
enterprise activities. We also saw some of the aspects of, what? For example, marketing as a very important
tool and function can do to support the enterprise, where with a smooth flow of demand from the
customer, it can always ensure that the harmony and the balance of the manufacturing system
can be maintained. So, it definitely plays a very key role with
the time to time updation of what the customer thinking or philosophy in terms of demand. The whole idea is to be able to give a smooth
demand pattern to the remaining part of the enterprise. So, that there are not many disbalances in
the enterprise itself. So, another very important aspect that, any
product which gets realized is basically the design of the product and it is the design
which actually restarting process to map the customer thinking in terms of something, which
is a need or want of a particular customer. So, we will definitely like to have a historical
perspective of how design can be done; obviously, nowadays product designing involves very complex
CAD tools: Computer Aided Design Tools, where there is a huge flexibility offered to the
design of that the product designer, to visualize whatever he thinks in terms of mapping of
needs of a customer. . And so we want to do a little bit of historical
perspective of design and as we have already seen design and manufacturing formulate core
activities, for realizing a marketable profit making system. And therefore, it is very important that design
be done in an appropriate manner. So, that not only from a stand point of mapping
needs of the customer, but also from a standpoint of giving a high quality product design is
a very important tool. In fact, there is a concept called Robustness
by design itself, which is the primary you know envisioning of the product capability
of a system itself. And if robustness can be introduced at a primary
level or an initial stage, then there can be a huge tolerance or variation that it a
product design can take in terms of the deviations of the manufacturing process and still be
able to manufacture the quality which is needed. So, that aspect is very important aspect of
any modern day manufacturing enterprise. So, if you look at the figure here, which
says the evolution of mechanical CAD/CAM systems; you can see that there are various levels
in which the design software which have enabled the designer hugely have emerged over different
years starting all the way from 1960 to the 1990s. So, definitely the Computer Aided Design technology
has emerged over the years to facilitate the at least you can say that representation completeness
of a design which is envisioned. And without doing that, that is the first
step how do you do the engineering specification it would then get translated into exact product
requirement, so manufacturing process requirements etc. So, the first step; obviously, is the very
good design, flexible design package which can handle the various design issues related
to the product design. So, the first step you know, the history if
you look back in the 1960’s, was the development of the 2-dimensional drafting system. Which was extended to the 3-dimensional models,
principally initiated by something called a wire frame based design model. If when we are going to do CAD, we are going
to address what exactly is a wire frame design. But it is actually a sort of you can say pseudo
3-dimensional representation, of at least the edges of an object through which you can
define the whole object. So; however, it was not possible to represent
the higher order geometry data, particularly data related to surfaces. Because when we are talking about edges, you
do not have any inter connectivity between the edges on a priori basis. It is just the representation of the edges
in the wire frame model, but if there is an inter-connection between such edges where
they are exact location coordinates etcetera, which has specified. Then the question of the surface mapping would
come into picture. But here it is only the wire frame and it
is assumed that the person who is visualizing the wire frame model would be able to sort
of map this surface on his own, without the CAD package going into the great details of
how the surface topology is going to vary between the edges. So, that is what the 1960s was; obviously,
in the 1970s surface based models were developed because the need was felt. For example, for complex topology surfaces
how a representation can be done in terms of numerical data or coordinate data. So, higher level CAD evolved where not only
the edges, but the surface became a very prominent application. And you know, it evolved the surface data
for boundary representations, although even this was again not very sufficient to represent
a solid volume enclosure. For example, information related to what would
be the volume of the particular object, if it is not a regular object cannot be just
had by looking into the surface data or the edge data. So, there were other versions which evolved
over time and there were a great many modifications which happened over the 70’s, 80’s, and
90’s. And you can see that from the 2-D drafting
to the wire frame design to the solid and you know surface on the solid modeling; and
then finally, the assembly modeling where which means that if you have 2 different solid
objects can I combined them together and contain them within certain volume, that we are looking
at. And then finally, parametric modeling and
knowledge based engineering which I am going to mention just about in a few minutes started
evolving with time. So, typically all the way up to assembly modeling
from 2-D drafting can be categorized this geometry-based modeling. And then these two other quantities which
are or two other forms of drafting which is called parametric modeling or knowledge based
engineering, they are more like rule based. And; obviously, they involve a particularly
the last step which is the knowledge based engineering they involve a lot of intelligent
processes like, not only just the geometry, or just the volume, or just the design; but
the finite element modeling aspect the process simulations for some physical phenomena associated
with the design that you are mapping, and again the complete design for manufacturing
and also a very important design optimization. So, this is basically an intelligent thinking
system which is now evolved, and nowadays all the software which comes in the CAD area
are really process knowledge based engineering; with that approach you basically start all
the engineering of design engineering. So, as I told you that up till 70s, when the
surface based models were still not very sufficient, then the question of how to map 2 objects
together or inter connect 2 objects together did not exists. There would be a sort of an emergence of the
assembly modeling approach. All the solid modeling schemes do have an
inherent weakness in that they provide a low level representation of parts in terms of
only geometric and topological data constituting the model. And as I told you the finally, emerged knowledge
base engineering system, not only includes only the design; but also the rules based
designing, particularly the engineering rules based designing. Like what kind of tolerances are there, what
kind of part dependencies are there between the different let us say surface finishes
of the different structures which were trying to assemble so on and so forth. So, these are not related to really geometry,
but some process rules which govern the designing process, but then that is the modern way or
modern approach of doing all product design. . So, that is a sort of a historical perspective
to design. Let us look at the manufacturing part. So, modern manufacturing, if you can just
split up into really a series of interrelated activities and operations and that can involve
let us say design, that can involve: material selection, planning, production, quality assurance,
management, marketing of discrete consumer and durable goods so on and so forth. So, there is a huge scope that there has to
be synergism between the various wings that have been mentioned; right about now within
an enterprise for a successful production in a modern manufacturing environment. There are some other attributes to modern
manufacturing: one of them is a classification, you can classify manufacturing processes into
continuous and discrete systems depending on the product line. Talking about manufacturing of oil and natural
gas or maybe you know production of something like sugar, it all necessitates a continuous
production process. Now this course will not be intended for such
systems, mostly this course focus more on a unit by unit or discrete production system
what happens in assembly line. And all the theorization that we do in the
following few lectures or modules will be related to mostly discrete process, discrete
production processes. However, modern manufacturing does include
a very flexible attribute where you can combine mass production with job shop kind of production
and these systems therefore, are also known as flexible manufacturing systems. There may be some processes which necessitate
a continuous activity for example, sheet rolling in a car making industry is a continuous process. But then the moment it gets into a press shop
and the sheet is pressed into different parts, it becomes a discretized process. So, if you wanted to backwardly integrate
at some point of time you have to combine really, the continuous flow production with
the job shop kind of or the discretized kind of production unit systems which will probably
focus more on this along this course. Also, the attribute of modern manufacturing
systems are to a variety of modern tools which are available from the engineering technology
side, which includes things like computer numeric control, which includes things like
let us say automated guided vehicles with their different aspects. And also heavily relies on robotics and also
group technology approaches, which eases out the manufacturing sequencing or the process
sequencing in a manner. So, that you always tend to produce optimum
yield in any business environment of any kind of pressure whatsoever. . So, these are some of the attributes related
to modern manufacturing. Let us actually look at a little more historical
perspective of how modern manufacturing had evolved. And you know the concept of a factory and
productivity improvement is really attributed to the Adam Smith, he was a Scottish national. And he had this famous work on the division
of labor entitled and enquiry into the nature and causes of the wealth of nations. This is one of the first treatises drafted
in 1776 which talked about the modern day economics or capitalism and concepts related
to how manufacturing would augment such economic systems over in the world. So, following this in year 1913, the manufacturing
really had to see the day of in about next probably 2 centuries. So, a giant leap towards the modern day, so
called manufacturing happened in United States when Henry Ford for the first time introduced,
the first concept of assembly line. So, this was in relation to domestic cars
and this was one of the first initiatives where people realize how important it is;
when you chain up the sequence of process in a complex engineering object like let us
say a product like car. So, that you have the zeal and enthusiasm
to keep producing on a mass production basis on a unit by unit basis, these technology
products. There was some other philosophers like Frank
Gilberth and Henry Gantt, they developed the concept of motion study and elimination of
wasteful motion. So, this was an ice on the cake of what, Henry
Ford had developed earlier. In an assembly line there was a continuous
use of skilled expertise of variety of people at a certain rate, and there is always something
called wasteful activities or non-value added activities which will happen in the process
of the assembly. For example, in a car assembly there may be
a tendency of all the people to do their job in a manner which they probably do not realize
because that is the easiest approach that they have. But they are doing a lot more than what they
should have done. So, there is a philosophy that in an engineering
way or in a very logical manner if you can observe the motion sequence of a particular
operator associated with an assembly line, and then try to identify those areas which
are really non value adding in nature and eliminate them. In a way so that it does not feel any uncomfortable,
you know situation. In that case you can save a lot of time. So, basically these Frank Gilberth and the
Henry Gantt were two such people who were associated with some of these elimination
of wasteful motions, and also a systematic graphing or a planning approach. So that, you can always have the bottle necks
of a manufacturing process in terms of the most critical and the least critical. So, then also things like related to scheduling
of the activities or related to let us say the progress review or regular updating of
data related to the manufacturing process in a very easy manner can it be represented. So, that everybody around can have knowledge
about the manufacturing process itself, without really having to go into the depth of the
process. So, these two were really very good value
additions again to the modern day manufacturing. And then; obviously, the breakthrough which
was done by G.C. Devol can be taken as a again a very important
historical step towards modern day manufacturing; who developed the controller device in the
year 1946, that could record electrical signals magnetically and play them back to operate
a mechanical machine. So, this actually was the advent of the computer
assisted machining systems, which later on emerged as the highly technological in most
advanced domain of computer numeric control machines. So, this is the way that modern day manufacturing
kind of evolved from the very first work in 1776, all the way to the current you know
with the last century. And; obviously, there was some grade breakthrough
which were made after this controller device was launched. One of them was the first numerical control
machine which was developed at MIT under a subcontract from the Parsons Corporation,
Michigan on air force funding in 1950. There was also the development of automatic
tool changers and indexing work tables that were added to this CNC machine in 1960, and
then it started an era of manufacturing. The people started talking about integrating
such numerical control machines into a one particular industry or one particular area,
where they would have a direct control of a central processor governing many such NC
or numerical control machines. So, there would be one processor which would
be governing more than one numerical control machine. So, the control system development in 1971
was again the next milestone, which led to the development of the micro controller controlled
NC. So, called CNC or the localized or the globalized
control by the direct numerical controlling, you know system or software again merged into
a manner. So, that you can have now, the control at
local level of the machine without that global monitoring or global computing being required
anymore. And nowadays the whole integrated one machining
unit would have one controller of its own, and that controller can be linked to some
other master controllers which would control; but then the processing capability, the intelligence
capability are all now sort of synchronized to with a particular machine tool rather than
the global system of machine tools that was before in the DNC setup. So, the major advantage of CNC machine is
its ability to store part program. So also interact with controllers of central
computers, as I just told. And the power of NC machine was further enhanced
in 1980 by making them capable of carrying hundreds of tools having multiple spindles
controlling movements up to six axis so on and so forth, so that very complex parts
could be produced. So, I think this is a sort of an evolution
process of how modern day manufacturing has evolved, there are many other systems which
have been added to the manufacturing like very good material handling systems, very
good automated you know robotics system, which would always assist in optimizing the existing
manufacturing rate with lesser and lesser inputs. So, we would like to conclude this module
at this particular stage and start with the next looking at some of the fundamental material
handling systems etcetera, and start some basic CAD in the next module. Thank you. 1

2 Comments

  1. Dead pool says:

    Title is wrong this lecture is on history of machining

  2. Srikanth Rangdal says:

    1 millennium years back?
    Look at the time 2:25.
    Did even humans exist so early?

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