Mould cavity-

The mould cavity which holds the liquid metal is complementary to the final product. The mould material, therefore, must withstand the superheated liquid metal. For single castings, the mould is cereal, with water.

Shake allowance-

The vertical faces of mould cavity gets enlarged due to shaking or tapping of pattern for easy removal from mould. This causes slight enlargement of mould cavities and often a negative allowance in the form of shake allowance is provided to compensate for this enlargement.

Distortion allowance-

In order to prevent distortions, particularly in long and thin sections, U and V-sections of castings, and in irregular-shaped castings, often extra material in the form of distortion allowance is provided.

Machining and finishing allowance-

Since the surface finish and dimensional accuracy achieved by casting is not very good, certain extra metal is provided on the casting which can be removed during finishing. This extra material is called the Machining and finishing allowance and is typically in the range of 1.5 to 9.0mm, depending upon the material and size of casting and the finish required.

Draft allowance-

A taper of 0.01 to 0.025mm/mm is generally provided on the vertical faces of the patterns for its easy withdrawl from the mould. The taper is called the draft allowance.

Shrinkage allowance-

Shrinkage allowance is provided to compensate for contraction of the casting when the temperature of the solidifying metal in the mould cavity drops from freezing to room temperature. Shrinkage allowance is generally in the range of 0.01 to 0.016mm/mm, depending upon the type of material.

Pattern and mould-

A pattern is a replica of the desired casting and is used for making the mould cavity. Various types of patterns are used in casting - the choice depending upon the production quality and the casting configuration. Single-piece patterns are obviously least expensive but have limited applications. Split patterns or two piece patterns are most widely used since it can be easily withdrawn from the mould and can be used for intricate shapes.
Patterns are always made somewhat larger than the final casing to allow for shrinkage, distortion and finishing. These are taken care by shrinkage, draft, finish, distortion and shake allowances.

Pattern and mould-

A pattern is a replica of the desired casting and is used for making the mould cavity. Various types of patterns are used in casting - the choice depending upon the production quality and the casting configuration. Single-piece patterns are obviously least expensive but have limited applications. Split patterns or two piece patterns are most widely used since it can be easily withdrawn from the mould and can be used for intricate shapes.
Patterns are always made somewhat larger than the final casing to allow for shrinkage, distortion and finishing. These are taken care by shrinkage, draft, finish, distortion and shake allowances.

The casting process-

• Pattern and mould
• Melting and pouring
• Solidification and cooling
• Removal and finishing

Metal Casting-

Casting is the oldest and perhaps the most popular mean of producing the desired shape. The final product or the casting can be made from any metal that can be melted and have virtually any configuration. Castings have been produced in sizes varying from few millimeters to several meters and can weight from few grams to several tons.
The process basically involves melting and superheating the raw material up to the desire temperature. The molten metal is then allowed to solidifying in the mould cavity and on cooling, the product is taken out to get the casting. Several casting processes have been developed over the years - each having its own characteristics, applications, advantages and limitations.

Manufacturing Processes-

1) Constant mass operations-
2) Material removal operations
3) Material addition operations-

The basic manufacturing processes that fall under each of these classified into different categories. In order to meet the basic requirements of quality and service life of manufactured products at a competitive price, the engineers associated with design activities must be well-acquainted with the various manufacturing processes. While it is not possible to cover the various aspects of manufacturing processes. The emphasis is on the fundamentals of basic manufacturing processes- casting, forming, machining and welding.

Heat Treatment-

Heat treatment operations involve controlled heating and cooling of metals for the purpose of altering their mechanical and metallurgical properties without and international change in the shape and size of the work piece. Heat treatment operations commonly used are hardening, tempering, normalizing and annealing.

Welding-

In welding, two pieces of metals are permanently joined together by coalescence resulting from application of temperature and pressure. Depending upon the range of temperature and pressure used a wide variety of welding and allied processes are now available and used in manufacturing. The most commonly used welding methods are arc welding and gas welding.

Machining-

Machining essentially involves removal of excess material to get the desired shape, size, accuracy and finish of the product. In conventional machining processes, material removal is achieved through tool-work interaction. The tool used may be a single-point tool such as those used in turning, shaping and planning operations, or a multi-point tool like those used in milling and drilling operations. When bonded abrasives are used as a tool, the process is known as grinding.
A number of new machining methods have been developed which use new energy modes for achieving material removal. These machining methods have come to be known as unconventional machining processes and include electro discharge machining, electrochemical machining, ultrasonic machining and laser beam machining.

Forming-

In forming operations, the desired shape and size are obtained by plastically deforming the material in solid state. It basically makes use of the ability of materials, usually metals, to flow plastically when subjected to high stresses. Primary forming operations include forging, rolling, extrusion, wire drawing and deep drawing. These opertions are carried out either above the recrystallization temperature of the material being deformed.

Casting-

In casting processes the liquid metal is poured into the mould cavity of desired shape which on solidifying takes the shape of the cavity. Sand casting, investment casting, die casting and continuous casting are some of the commonly used casting processes.

1) Process-type manufacturing-

It involves continuous processing, that is the material goes through a series of process steps in a continuous manner which eventually gives the finished product. This type includes production of raw material and chemical products. The fabrication-type manufacturing involves production of discrete components and is achieved by changing the raw material into a final product using manufacturing processes and assembly operations.
The manufacturing processes that are used in fabrication-type manufacturing can be classified into five broad categories-
a) Casting
b) Forming
c) Machining
d) Welding
e) Heat treatement

Manufacturing Processess-

The main activity of manufacturing is to convert the unfinished product into a useful product. This can be achived through two principal types of manufacturing-
1) Process-type manufacturing
2) Fabrication-type manufacturing

Role of Manufacturing in Design-

A design engineer may come up with a product design which is functionally of high quality but if it has to become a reality, it must be produced at a competitive price and in a reasonable time to achieve customer satisfaction. Thus, in order to satisfy the basic requirements of quality and service life at an affordable price, the designer must be fully acquainted with the manufacturing methods or must collaborate closely with those who are specialist in the area.
The major step towards integration of design and manufacturing has been brought about by computer-aided design and computer-aided manufacturing. Earlier the use of computers was primarily confined to drafting, but with enhancement of computer capabilities, its use was extended to analysis and design activities and came to be known as CAD. CAM started before CAD and was developed essentially for process programming for computer controlled machine tools. Marging of these two areas led to the development of what has come to be known as computer-integrated-manufacturing. CIM is therefore, total integration of all aspects of design, planning, production, marketing and management.

What is Manufacturing-

Manufacturing now involves making products from raw materials by using various kinds of machines to carry out a variety of operations in a well-organized and coordinated manner. Manufacturing, in a broad sense, is the process of conversion of raw materials into final products. Here, product means something that is produced to satisfy human needs. Manufacturing therefore implies creating value by applying useful mental and physical labour. Fundamentally, manufacturing may be considered to be a process of technological transformation of a set of input elements into set of output elements whereby the utility of the product is increased. The technological transformation is optimized by considering both input and output elements as variables. The criteria for optimization could be increased utility or enhanced productivity. Utility may be evaluated in terms of revenue or profit, while productivity may be evaluated in terms of the number of pieces produced per unit time.

The Detailed Design-

This includes providing detailed manufacturing instructions in the form of part drawings, assembly drawings and process instructions. Specifications of each part, components or subsystem are defined so that a manufacturer knows exactly what has to be made and how. Before such description are finally arrived at, the designer has to bring in the considerations of tolerance. Perfect accuracy cannot be achieved with any machine or process. No machine, no matter how precise, and no workman no matter how skilled, can produce two components that are exactly alike.

Fault repair-

On the other hand, is undertaken whenever a fault which shuts down the system occurs. This can upset schedules of operations.

Preventive maintainance-

It is carried out on a fixed schedule that is arrived at by sound technical considerations.

Designing for Maintainance-

All products, whether big or small need maintainance. It may be the replacement of an electric fuse, or servicing of an automobile or even the overhauling of an aircraft jet engine. Servicing of automobiles and aircrafts is basically preventive maintainance. Its purpose is to inspect the components, change the lubricants , tighten the nuts and bolts which may have loosened because of vibration in use, and correction of minor failures which, if not corrected, may lead to catastrophic failures.

Designing for Use-

A short or too tall a person is always made to feel that he is abnormal. Many products are designed for just the average person, with no thought for the fact that fully 50 percent are below that normal and another 50 percent above it. If only a margin for adjustment was provided, a lot more person would be happier. Many products inconvenience even a normal person. A person has to be a contortion artist to slip in and out from behind the steering wheel of most automobiles. Common household scissors threaten permanent cramps in fingers and palms.
A designer will do well to remember that the product he develops is to be used by people. A well-designed product is one that can be used by people more comfortably, more safely and with more efficiently. It is the product that should be fitted to the person, rather than the other way round. Designing for use essentially consists of ensuring that the points of conflict between machine and men be rounded out in favour of men.

Designing for Shipping, Handling and Installing-

Whether a large piece of equipment or a small consumer item, it needs to be shipped from the factory to the user. It must be packed so as to withstand the conditions encountered in transit. These include the rough handling that a package invariably receives at the time of loading or unloading, the vibration and shock encountered during transit, and the adverse humidity and temperature conditions in transit. We should provide suitable reinforced lifting hooks if the equipment is heavy. Rollers and castors may be installed on some heavy equipment. It may be advantageous to design the frangile parts of an assembly so that they can be packed and assembled on site.

Designing for Production-

As soon we start giving a physical shape to an abstract concept, we must start considering the question of how it will be produced. Designing the structure of a tall building must be accompanied by considerations of how it is going to be erected. If the building is more than a few stories high, we cannot use ground based cranes for work on the higher levels. A design is worthless if it calls for higher accuracies than can be obtained with the machines available to the producer. A good designer always asks himself the question-
• Can this is made with the available machines and skills?
Every method of manufacture has certain strong and certain weak points. A good design utilizes the strong points of the available manufacturing methods.

Example of Designing for Function-

Consider a power plant engineer charged with designing a cooling tower for water used for cooling the plant. The designer decides, based on a preliminary evaluation, on a wet-type counter-flow forced-convention tower. For this he have to calculate how much heat is needed to be removed per hour. He would then provide for that much water must evaporate per hour. He would then provide for that much evaporation by designing the proper height and cross-section of the tower, the dimensions of the wet-pack, and the optimum shape and size of the fill material. For this he needs knowledge of diffusive and convective mass transfer . he will also require knowledge of thermodynamics and heat-transfer processes. He will also calculate the size and power of the blower or fans require for obtaining the desired rate of air flow.

Designing for Function-

The first requirement of any design project is to deliver a product that measures up to the function specifications. If specifications of a combat aircraft call for a cruising speed of 2.5 Mach, a penetration of 1,000 km and a ceiling altitude of 15 km, the first task of the designer is to make sure that these characteristics are achived. The handling performance requirements, essential through they are, come over and above these functional requirements. If we are structural engineers and our task is to prepare a structural design for an 80-storey building, the first requirement is to produce a structure that can take up the load of 80 storeys, can withstand earthquakes and wind loads of reasonable magnitudes.

The path from design concept-

A final acceptable design is a long and winding one. The development phase of the design process consisits of putting the major elements of the concept togetherkeeping in mind that the resulting product should satisfactorily perform the expected functions. However, the acceptability of a product does not depend entirely on its functional utility or efficiency. A product needs installation, operation, maintenance and repair. The effort needed and the attention required for these functions are important determinants of the quality of the product as it appears to the user. To this end, therefore, the designer must build into the design, ease-of-use, installation, maintenance and repair. All these considerations constitute the preliminary design stage of the design cycle.

From Concept to product-

The abstract design concept consisting of the outline, an idea from here and a mechanism from there, expresses only a plausible relationship among elements thatpromises to fulfill the needs of the given problem. We then carry out a feasible study to estimate the chance of such plausible relationship being converted into a physical reality. However, unless we actually do produce the envisaged physical reality it is merely an intellectual exercise. The next step in the design process is the development of the design concept into a design that will work to the satisfaction of all concerned.

Using Utility for Design Selection-

To be able to use utility analysis for the selection of a design concept we need to further develop the concept of utility. It has been said that utility is a measure of the usefulness of a product, and that equal intervals on the utility scale of the different quality dimensions should be interchangeable, that is, substituting one unit of utility of say, realibility should not affect our performance. However, to construct such a utility scale is a tall order. To overcome this problem we use a slightly modified and simplified procedures, through the end result still remains the same.

The Concept of Utility-

The concept of utility has been developed as a common scale for evaluation of a product on a number of diverse dimensions such as cost, safety and ease-of-use. This scale is based on the personal preferences of the evaluator, and as such, is highly subjective. The utility of a product on a particular quality dimension measures the usefulness of that particular quality characteristics of the product in the opinion of the evaluator. Thus, the utility of a design on, say, the adaptability dimension is a measure of the contribution of the adaptability of the design to the overall usefulness of the product. The overall utility of a product is the sum of utilities of each of the quality dimensions

The Quality of Design-

Economic profitability is an important quality of a design, but only from the manufacturer’s or distributors point of view. The customer pays for the designed product, but except in the case of capital goods, does not create any monetary income from it and is, therefore, unable to calculate its profitability or economic worth.

Economic and Financial Feasibility-

All objects or systems by an engineer are directed towards some purpose. It is understood that for a design to be worthwhile the effort that goes into its realization should be substaintially less than the benefit obtained from it. One method of measuring the effort of designing and production is to measure the amount of money it costs in terms of wages and materials.

A Measure of Physical Realizability-

The physical realizibility of a design concept can be measured in terms of the confidence the designer has in his being able to transform the abstract concept into its physical embodiment. This confidence is expressed as a statement of subjective probability.

The place of Decision-making in Designing

When the search for solutions is carried out under such conditions, the outcome is a set of ideas, each of which is a rather rough outline of how the major elements of the design are to be connected. Each of these needs to be developed further, the details worked out and the procedures specified. The development of design costs and time and money are the important factors in designing.

Morphological Analysis-

This method serves to force the designer to increase the area her search for design concepts. It recognizes that the solution to a design problem consists of certain essential constituent parts and a good design is one, which selects the proper ‘ matching combination of component’. It is based on the premise that novel designs can be created by treating most designs.

Search for Design Concepts-

A successful designer is one who can handle more information more profitably. The design method attempt to externalize this complex private thinking of designer, with the hope that this leads to a systematic exploring of the relationships between various elements. The externalization is carried out to different methods. Some of these only attempt to clarify the essential components of the design problem.

Use of Checklists-

The use of checklists to remind oneself of all that needs looking into is a standard practice in many areas. The checklists helps against the danger of mental fixity settings in which may leave the designer stranded in some blind alley.

Creativity by Analogy with Prior Systems-

Most of the original designs are original only in that they use a particular combination of element for the first time. The creative process is simply the formation of new combinations from pieces already present in the mind. The important thing to notice here that none of the components he chooses were designed or made for the particular machine he has he chooses were designed or made for the particular machine he has in mind.

Mental Set or Fixity-

One of the greatest hindrances to all design effort is the tendency of most people to get into a mental rut. There develops a permanent set in the mind that tends to suggest only the commonplace and the familiar ways of looking at problems.

The Creative Process-

Once the designer has the creative attitude, how does he begin creating? From the accumulated experience of many highly creative individuals, the researchers in creativity tend to agree that the secret if inventiveness is to saturate the mind with all the information pertinent to the problem and then let it incubate. One should become thoroughly familiar with the problem, try to understand all the sub-problems that must be solved for overall success, attempt a few trial associations.

Introduction-

Design and manufacturin activities initially evolved as seperate activities, totally delinked from each other. Traditionally, the design depertment completed the drawings and specifications of the product and passed them to the manufacturing department to produce.

The creative attitude-

Perhaps the most important determinant of the creative effort is the attitude one bring to the task problem solving. More often than not, the negative outlook and pessimism stand between the designer and the truly innovative design. Self-confidence and a positive outlook appears to be essential ingredients of good designers.

The creative attitude-

Perhaps the most important determinant of the creative effort is the attitude one bring to the task problem solving. More often than not, the negative outlook and pessimism stand between the designer and the truly innovative design. Self-confidence and a positive outlook appears to be essential ingredients of good designers.

Solving the design problem creativity

Once the need is throughly analysed, and the design problem properly understood, there comes the all-important phase of thinking up ways to meet the design requirements subject to the design constraints. If the problem is not a trivial one or if it has not been previously solved in its entirety, the process of thinking up feasible solutions is not a straight-forward one for which a complete setoff rules or procedures can be prescribed.

Resources-

We may consider resources from two view points. One, the resources with the manufacturer of the device and two, the resources available with the users of the system, that is, the customers. The resources may be expressed as positive statements of availability or as negative statements of non-availability that can be called the constraints on the design. If we designing a bicycle for Indian villages to be manufactured at the small-scale industries level, the constraints of resources with the manufacturer consist of non-availability of heavy machinery, of highly-skilled labor and of high quality steel. The constraints of resources with the customer or the users may primarily be the lack of skilled repairmen. This may dictate the keeping of design as simple and easy to maintain as possible.

Environmental factors-

Temperature variations have important bearings on the design of the engine cooling system. Low temperature can cause such problems as icing thecarburators of aircraft engines. High temperature on the other hand reduce the structural strength of materials. Many electronic components do not work satisfactorily in temperature 60 degree celcius.
Vibration levels and accelerations have adverse effects on almost all systems. Vibration introduces a serious problem in aircraft structures because of fatigue.

Standards of performance-

Standards of performance are the set of complex requirement that cover a wide field which may include such things as reliability level, safety, convenience in use, adaptability under various condituons, ease of maintainance and cost. Each of these must be considered and due attention paid while designing. At the need analysis stage itself one must list the relevant performance parameters and, if possible, decide on the minimum acceptable performance on each of those parameters. This only settles tha minimum that must be met, and the competing designs are judged depending on how much they better these minimums. However, there are cases where deciding a priori the minimum is not at all an easy task.

Specifications-

Writing specifications usually calls for collecting information. The designer also needs to collect information about how high a person can write and how he can comfortably reach. This information would again be stastical in nature and the designer has to make a decision as regards how tall a person he should design the lowest point on the board for, and how short a person he should highest point on the board cater.

Analysis of Need-

There are basically two aspects in obtaining this definition, namely the specifications and performance parameters or standards of performance. Roughly speaking, specifications refer to the normal function requirements of a design that every design concept must meet, and standards of performance refer to those standards against which the competing designs can be judged.
The same requirement can have two different roles under two different design conditions. The cost of a car may be a specification if we are designing one for the middle-income group, but only a standard of performance will be the requirement if for entering it in an automobile race.

High level of preliminary need statement-

The higher the level, the wider is the span of concerns, but lesser is the possibility of attention to the details. An architect while designing the overall relationships among the spaces she creates has to worry about the location of windows and shutters. However, she obviously cannot be expected to consider the details of hinges and sashes to be used on the window frames. It is usually the interior designer who has to worry about these details, but if she too decides to design at the level of the inter-relationships between spaces rather than forever have an unfinished project on our hands. Somebody has to design at the lowest level of scope as well.

Preliminary Need Statement-

In this situation, the identification of the true need, simple as it may appear, is crucial first step in the design process, and one that is the stripping point for many projects. Quite often, the designers and the sponcers of the design identify the wrong need and take up a wrong problem to handle. This happens because quite frequently a designer starts thinking of the solutions enen before he has clearly identified the need and, thus, he is foredoomed to take the wrong track.

True need-

A design exists solely in response to a specified or a perceived need and, therefore, the satisfaction of that need is the most essential function of a design. However, this is not as simple as it appears. Very, often the statement of need that a designer starts her work with, is incomplete or even misleading. One of the most difficult problems faced by a designer is to isolate the ‘true’ need of a given situation from all the various expressions of need that she may be given.

Realization of need (2)-

Recognizing a need is in itself a creative process. It takes organized thinking and a disciplined mind, forever on the look out for challenging situations, to perceive most needs. Many of the great designers had an uncanny sense of recognizing the needs of society much before society itself realized them. Many of the problem encountered by a practicing engineer are however those that are communicated to him by his employers or customers

Realization of need (2)-

Recognizing a need is in itself a creative process. It takes organized thinking and a disciplined mind, forever on the look out for challenging situations, to perceive most needs. Many of the great designers had an uncanny sense of recognizing the needs of society much before society itself realized them. Many of the problem encountered by a practicing engineer are however those that are communicated to him by his employers or customers

Realization of need (1)-

The beginning of every design project is recognition of need. A need may be the just wish of a lazy man who wants to a robot to get him a glass of water when he is relaxing in an easy chair. Inventions are not for just fulfilling our material needs. If we look at the evaluation of almost any product we see that we are neversatisfied with just the basic product that does the job adequetly. We want beauty and ornamentation as well as in our machines and tools. Most of the early technology was concerned with development of dyes, paints and pigments for decorating clothes we wear, walls of our temples, houses, and other material things like ploughs, kitchen utensils and swords

Design making and iteration-

Design making plays a crucial role in the design activity. As already indicated, a desiger has to evaluate various alternatives at each stage and make a decision as to what promises to be the best. It should be remembered that most, if not all, design decisions are decisions under uncertainty and insufficient information. The uncertainty arises out of two sources. One, in which it is due to the reason that the required additional information depends upon the decision itself and two, in which it is due to stastically random processes.

Detailed design phase

In this stap the preliminary design is carried through to finality. Detailed dimensions, tolerences, finishes and other neering descriptions are furnished in this step. The optimum use of resources, both raw materials and production facilities is also ensured. The outcome of this stage is a design complete in every way so that it defines the exact product as it would be when it comes off the production line. The only step after this is the implementation of the design and its testing.

Convergence phase-

In which the designer attempts to eliminate the unworlable and the not-so-good solutions thrown up in the creative search for ideas. He attempts to converge on to the best solution under the given condition of the problem. It involves choosing from among the various possible creative transactions, developing it further, testing it as to wheather it can fulfill all the expectations, resolving sub-problems that may crop up at this stage.

Transformation phase-

In this phase the most exciting part. This is the creative phase wherein the designer summons all his experience, innovative capabilities, insights and genius to think up plausible schemes for achiving the desired result.For this, he uses the information collected in the first phase. This phase is termed as transformation because it serves as a bridge between the information concerning the problem and inputs on the one hand and the desired results on the other.

Explorative phase-

In this phase the aim of the deigner is to get as much understanding of the problem as possible. This understanding usually involves getting familiar with the exact nature of the problem, a research into the existing solutions, their shortcomings, etc. it is necessary that in this explorative phase the designer takes care not to be unduly influenced by the existing designes.

A Description of the Design Process-

The notion that a beginner in design may have about designing is that it involves high-level creativity, flashes of insight, inspired guesswork, or that it is work of major or minor geniuses and eccentrics. He may picture a designer slaving away at his drawing board along with his computer. He may imagine adesigner to be a mechanical mind tinkering away with assorted hardware and junk in his backyard. If one casually reads the case studies of innovative products, the design activity appears to be more like a lucky breake than a serious, planned scientific work.

Modern design problems-

Modern design problems are far more complicated than the traditional ones and cannot be handled by the method of trial and error because of the following reasons-
1) The traditional craftsman made things on a very small scale and thus the penalty of a wrong choice of design was limited.
2) The increasing scale of production has also introduced another complication in the process of design.
3) The rapid pace of technology change makes drastic and novel demands that cannot be met by small change.
4) The traditional designer was concerned with only one component or one product at a time.

Inadequency of evolutionary Method in Modern Design Situation-

The traditional method of designing by evolution and slow change through trial-error are no longer adequate in the modern industrial world. Perhaps the most visible sign of the need for newer and better methods of designing is the experience of the massive unsolved problems that afflict modern society. In industrially advanced as well as non-so-advanced countries, the magnitude of such problems is truly frightening. If the world has to be fed and the standard of living of a vast majority of its population has to be raised above the bare substance level at which it is at present, we need a design revolution. Even the well to do countries are suffering under the burden of the problems created by the very industrial activity which is responsible for their wealth.

Design by Evolution-

One characteristic feature of this process of design by evolution was that the designers worked largely by themselves, and communicated their ideas to others only through their work. Pieces of design onformation were stored in memory, learnt and passed down during the long periods of apprenticeshop of the master craftsmen. The overall shape of the product and the process of achiving it were passed on to the future generations of artisans, but the reasons for the same were lost in the absence of any tradition of codifying the design features.

Aesthetics-

A washing machine, even if it sits in the laundry room, must not just wash clean but most also look beautiful if it is to find customers. The source of our aesthetics, which is mainly concerned with what liiks right from a functional point of view, is primarily the observation of nature. A building shaped as an inverted pyramid would generally not lok right because it appers to be unstable

Method-

The method refers to the materials, tools and processes used for the execution of the design. A design must reflect the process used for executing it. The greate strength of steel in tension has been exploited to the extrame by pretensioning the spokes so that they are always in tension , even the externally applied load acts in a way that would have caused compression if there was no pre-tensioning.

Use-

The product that a designer develops is to be used by people. A well-designed product is one that can be used by people more comfortable, more safely and with more efficiency.

Need-

A design exists solely in response to a satisfied or a perceived need and, therefore the satisfaction of that need is the most essential function of a design

Purpose of design-

One of the most fundamental problems that every designer has to struggle with is to know that a good design is. Of course, he must design optimally and he must design to satisfy a need. But if we see what man is never satisfied with just the basic product that does the job adequqtely. Functionaaly the product is the multi-faceted concept. We in general recognize four major dimensions of functionality.

The process of design-

Design activity as defined above can be seen as process of building a bridge across the divide between the available resources available on one side, and the needs, desires and aspirations of mankind on the other. What makes the design process particularly difficult is the fact that designing in like fonding one’s way in a jungle without any map. There is very little to guide one along. There may be some experience with related or similar problems. But for a new problem, in general, one little to start with except a few ideas which are more in the nature of hope than anything else.

What is designing?

To design is to innovate and to create. The inventions of the wheel, the plough, the hurricane lantern the steam engine. The electric generator and the motor, the wireless and the computing machine are all designs of greater or lesser significance. However, an engineer is not the only person who designs. Almost all human activity seems to be revolving around design. It is an activity directed towards a need; it is creative; and it is concerned with the best use of resources.
Design is a process concerned with generating ideas and suggesting ways to turn these ideas into reality to satisfy some needs optimally under the trelevent constraints.

Introduction-

Design and manufacturing activities initially evolved as seperate activities, totally delinked from each other. Traditionally, the design department completed the drawing and specifications of the product and passed them to the manufacturing department to produce. Design and manufacturing activities have, therefore, been carried out sequentially rather than concurrently. This often encountered difficulties because the design engineers could not anticipate production problems and this lack of communication often resulted in loss of production. An innovative approach to design is therefore, essential for the product to compete successfully in the market through savings in material and production costs. This requires the design engineer to be knowledgeable about the interrelationship between material, design and manufacturing, as well as the overall economics involved in developing a product. A synthetic approach towards integration of design and manufacturing is therefore, essential for optimizing all elements of the integrated manufacturing system.