Fundamentals of design and manufacturing


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Fundamentals of design and manufacturing

  1. 1. Design and Manufacturing - Study Notes Chapter 1 DEFINITION OF ENGINEERING DESIGN 1.1 Introduction: The economic future of India depends on our ability to design, make and sell competitive products. Excellent design and effective manufacture are the pre-requisites of a successive industry. There is a general impression that the quality of Indian products can still be improved. The fact that consumers have lost their confidence on Indian-made products cannot be denied. This problem can be solved only by designing and manufacturing better products through improved methodology. Keeping this in view, the subject “Design and manufacturing” purpose to present the methods and procedures of design and manufacture. Although engineers are not the only people who design things, the professional practice of engineering is largely concerned with design. It is usually said that design is the essence of engineering. The ability to design is both a science and an art. The science can be learned through procedures developed by eminent scholars. But the art can be learned only by doing design. • Types of Products A product is the tangible end result of a manufacturing process and is meant for satisfying human needs. The product can be classified as follows: - • Convenience goods These are less expensive and are clustered around shops and restaurants. These can be purchased at consumer's convenience. E.g. Cigarette, Candy, Magazines etc. 2. Shopping goods These are expensive and people buy it less frequently. E.g. Jewelry garments etc. 3. Specialty goods These are purchased, taking extra pain. E.g. Rare objects like stamps. 4. Industrial goods.
  2. 2. These are items used in the production of other items. Eg: Raw materials. Another way of classifying products is into, (a) Continuous Products, and (b) Discrete products The continuous products are those which are produced in a continuous fashion. For example, plates, sheets, tubes and bars etc are produced in very long lengths, and then these are cut into desired lengths. On the other hand, discrete products are produced one after another, each in separate units. On the basis of the output product, the Industry is usually named as continuous industry and discrete industry. 1.3 Requirements in a good product • Customer Satisfaction • Profit How to achieve customer satisfaction? -The product should function properly. -It must have desired accuracy -It must have desired reliability -It must be easy to operate -It must be serviceable -It must make minimum space utilization -It must withstand rough handling -Pleasant appearances. -Reasonable price. How can it be profitable? -It must be easy to manufacture -The raw material must be cheap and easily available
  3. 3. -The manufacturing process has to the decided on the basis of quantity to be produced -It must use standard parts -It must be easy to pack and distribute. 1.4 Definition of Design: (S ‘94) Designing is such a vast field that it is defined in several ways. Various definitions of designing as pronounced by well-known designers are “Design is that which defines solutions to problem which have previously been solved in a different way” “Design is the conscious human process of planning physical things that display a new form in response to some pre-determined need”. “Design is an act of collecting all pertinent information for the production of goods and services to meet some human need”. The design of any component includes two things, • Product design • Process design The product design involves the development of specification for a product that will be functionally sound, good in appearance, and will give satisfactory performance for an adequate life. The process design involves developing methods of manufacture of the products so that the component can be produced at a reasonably low cost. 1.5 History of Design Process • Design by Single Person • Over-the-wall design • Simultaneous Engineering • Concurrent Engineering • Integrated design and Manufacture. In olden times one person could design and manufacture an entire product. Even for a large project such as the design of a ship or a bridge, one person had sufficient knowledge of the Physics, Materials and manufacturing processes to manage all aspects of the design and construction of the project. This period is referred to as the period of design by single person in the history of design.
  4. 4. By the middle of the 20th century products and manufacturing processes became so complex that, one person could not handle all aspects of design and manufacturing. This situation led to over-the-wall design process. In this method each functional departments were separated from others, as shown by wall. There was only one-way communications between Customer, Marketing, Engineering Design and production department. The customers ‘throw' their needs to marketing department. The marketing department may throw the customer needs to the design department, in many instances, orally. The Engg. Design department may conceive a design and hands it over to the manufacturing sections. The manufacturing department interprets that design and makes the product according to what they think suitable. Unfortunately, often what is manufactured by a company using over-the-wall process is not what the customers had in mind. This is due to lack of interaction between the different departments. Thus, this single direction over-the-wall approach is inefficient and costly and may result in poor quality products. By the early 1980's the concept of simultaneous engineering emerged. This philosophy emphasized simultaneous development of the manufacturing process- the goal was the simultaneous development of the product and the manufacturing process. This was accomplished by assigning manufacturing representatives to be members of design team, so that they could interact with the design engineers throughout the designs process. In the 1980's the simultaneous design philosophy was broadened and called concurrent engineering. A short definition of concurrent engineering is the simultaneous progression of all aspects, at all stages of product development, product specification, design, process and equipment etc. In concurrent engineering the primary focus is on the integration of teams of people having a stake in the product, design tools, and techniques and information about the product and the processes used to develop and manufacture it. Tools and techniques connect the teams with the information. Although many of the tools are computer-based, much design work is still done with pencil and paper. In fact, concurrent engineering is 80% company culture and 20% computer support. With the advent of computer technology, drastic changes have taken place in the field of design and manufacturing. The result was a completely integrated design and manufacturing system. This system makes a good use of technologies such as CAD/CAM, FMS etc. The computer integrated manufacturing
  5. 5. systems (CIMS) moves towards the ‘Factory of the future'. CIMS is necessary for better quality, efficiency and productivity. QUESTIONS • How can you explain the term design? Explain the process of mechanical design. Discuss the role of creativity in the design process (S'94, 8M) • The design of product is …..........customer expectations. (S'99, S'94) • .…………get first preference in design Ans. Functional requirements (S'93) • Explain the meaning of • Conceptual design • Functional design (iii) Production design. Give suitable examples for each. (S'03)
  6. 6. CHAPTER - 2 TYPES OF DESIGNS 2.1 The design can be classified in many ways. On the basis of knowledge, skill and creativity required in the designing process, the designs are broadly classified into three types • Adaptive Design (W 95, 97, 98 ‘00) • Variant Design (S 97, 99) • Original Design • Adaptive Design In most design situations the designer's job is to make a slight modification of the existing design. These are called adaptive designs . This type of design needs no special knowledge or skill. E.g. converting mechanical watches into a new shape. • Variant Design This type of design demands considerable scientific training and design ability, in order to modify the existing designs into a new idea, by adopting a new material or a different method of manufacture. In this case, though the designer starts from the existing designs, the final product may be entirely different from the original product. E.g. converting mechanical watches into quartz watches. Here a new technology is adopted. • Original Design Here the designer designs something that did not exist previously. Thus, it is also called new design or innovative design. For making original designs, a lot of research work, knowledge and creativity are essential. A company thinks of new design when there is a new technology available or when there is enough market push. Since this type of design demands maximum creativity from the part of the designer, these are also called creative designs. 2.2 On the basis of the nature of design problem, design may be classified as • Selection design • Configuration design • Parametric design • Original design • Re-design
  7. 7. • Selection Design. It involves choosing one or more items from a list of similar items. We do this by using catalogues. Eg. -Selection of a bearing from a bearing catalogue -Selection of a fan for cooling equipment -Selecting a shaft. • Configuration / Layout / Packaging Design (W 97, S'02) In this type of problem, all the components have been designed and the problem is how to assemble them into the completed product. This type of design is similar to arranging furniture in a living room. Consider the packing of electronic components in a laptop computer. A laptop computer has a keyboard, power supply, a main circuit board, a hard disk drive, a floppy disk drive and room for two extension boards. Each component is of known design and has certain constraints on its position. For example, the extension slots must be adjacent to the main circuit board and the keyboard must be in front of the machine. Keyboard Main Circuit board Extension slots
  8. 8. Floppy drive Power supply The different components are shown above. The designer's aim is to find, how to fit all the components in a case? Where do we put what? One method for solving such problems is to – select a component randomly from the list and position it in the case so that all the constraints on that component are met. Let's take keyboard first. It is placed in the front. Then we select and place a second component. This procedure is continued until we reach a conflict, or all the components are in the case. If a conflict arises, we back up and try again. Two potential configurations are shown above. • Parametric Design Parametric design involves finding values for the features that characterize the object being studied. Consider a simple example – We want to design a cylindrical storage tank that must hold 4 m 3 of liquid.
  9. 9. The volume is given by V = r 2 l The tank is described by the parameters, radius 'r', and length l . Given V = 4 m 3 = r 2 l r 2 l = 1.273 We can see a number of values for the radius and length, that will satisfy this equation. Each combination-values of r and l gives a possible solution for the design problem. • Original Design As described in an earlier section, an original design in the development of an assembly or component that did not exist before. • Redesign The redesign is a modification of an existing product to meet new requirements. It is same as adaptive design. Most design problems solved in industry are for the redesign of an existing product. Suppose a manufacturer of hydraulic cylinders makes a product that is 0.25m long. If the customer needs a cylinder 0.3m long, the manufacturer might lengthen the outer cylinder and the piston rod to meet this special need. 2.3. On the basis of the objective or strategy the designs are of following main types. • Production Design • Functional Design • Optimum Design • Production Design In production design , the designer designs something in such a way that the cost of producing the product is minimum. That is, the first responsibility of the designer is reduction of production cost. Hence, a production designer is concerned with the ease with which something can be produced, and that at a minimum cost. • Functional Design W93 In functional design , the aim is at designing a part or member so as to meet the expected performance level.
  10. 10. Functional design is a way of achieving given requirements.- but the same may the unproducible or costly to produce. A good designer, then, has to consider the production aspects also. A product designed without keeping all these aspects into account, wastes time, money and efforts. • Optimum Design [W 95] It is the best design for given objective function, under the specified constraints. 2.4 On the basis of the field/ area or the domain of design, the following types are important. • Mechanical Design • Machine Design • System Design • Assembly/sub-assembly design • Computer aided design • Mechanical Design It means use of scientific principles, technical information and imagination in the design of a structure,or machine to perform prescribed functions with maximum economy and efficiency. • Machine Design It is the process of achieving a plan for the construction of a machine. • System Design System Design is an iterative decision making process to conceive and implement optimum systems, to solve problems and needs of society. • Assembly/sub-assembly design [S 93] In the design of Assembly/sub-assembly the major criterion is the fulfillment of functional requirements. The assembly has to be designed to meet broad technical parameters and purpose for which it was meant. The characteristic features are: • The total number of parts used in the design must be minimum. • Sub-assemblies should be capable of being built separately in order to give maximum manufacturing flexibility. • Standard parts may be used.
  11. 11. • Flexible parts should be avoided, as they are easily damaged during handling and assembly. • Computer aided design [CAD] It is a design methodology in which the designs take the advantages of digital computer to draw concepts, analyze and evaluate data etc. Computers are largely used in a design office for simulation and prototype study. In modern design, computers have become an indispensable tool. Other types of designs are Probabilistic Design Industrial Design Probabilistic Design [S 96] It is a design approach in which design decisions are made using statistical tools. Generally, the external load acting on a body, the properties of materials etc are liable to vary. In probabilistic design, the designer takes into account the variations of such parameters. Industrial Design [W 93] It is the design made by considering aesthetes, ergonomics and production aspects. Questions 1. What are the characteristics features of system design, assembly/sub-assembly design and component design? Explain briefly with the help of examples. [S'93, 5M] 2. Distinguish between functional design and industrial design. [W'93] 3. Discuss the meanings of conceptual design, creative design, adoptive design and variant design. [S'97] 4. What are the three main types of design? Give a comparative analysis. [W'00, W '97] • Explain the difference between creative design, adoptive design and variant design. [S'02 W'98] • Designing for function involves the use and knowledge of …………….. Ans. Eng. Sciences [W '94] 8. Explain the meaning of • Conceptual design, (ii) Functional design and (iii) production design. Give suitable example of each. [S0'3] 10. Explain layout design. [S0'2]
  12. 12. Chapter 3 DESIGN PROCESS AND ITS STRUCTURES 3.1. Introduction Developing a manufacturable product is not an easy job. This chapter presents some methods that help achieve quality products. Rather than making a detailed study, only an overview of designing process is attempted here. 3.2. Features of design process The following features can be observed in a design process. • Iteration • Decision-making • Conversion of resources • Satisfaction of need Design is completed in many phases. In each phase, repeated attempts are required to accomplish the aim. A satisfactory conclusion can be reached on, only after a number of trials. Decision-making is essential for a designer to select one out of several. A designer often comes across several equally acceptable alternatives to meet some end. In such conflicting situations, designer has to make the best decision. In any design process, there is conversion of resources such as time, money, talent, materials and other natural resources. All designs are aimed at satisfying some human need. Needs, whether important or unimportant is the starting point of design. 3.3. How a design is born? In a broad sense there are two methods by which a design comes into existence. • Design by evolution (Traditional Design) • Design by innovation (Modern Design) • Design by evolution
  13. 13. This implies the traditional method of design in which the objects and articles that we see around has taken its present form by gradual change of time. If one looks at history it can be seen that most of the tools, equipments, implements, took a long time to acquire their present form. Things changed gradually with the passage of time. Each change was made to rectify some defects or difficulties faced by the users. Bicycles, calculators, computers, steam locomotives etc. all went through a process of evolution in which designers tried one concept after another. Even today this process is being used to some extent. However, this evolutionary process is very slow. i.e., it took a very long period of time to occur even a slight modification. The main reason for this slow evolutionary process of design was the absence of proper information and design data records. In modern design situations the evolutionary methods are not adequate because of the following reasons. 1. The traditional designing did not consider the interdependence of products. They were concerned about only one component /product. But in the modern world, the existence of one product is dependent on another in some way or other. 2. In the past, production was on small scale. Thus the penalty of a wrong design was tolerable. But, in the present time, production is on large-scale basis. As a result, any penalty of a wrong design will cost great loss. 3. Requirements of the customers of today's world changes so frequently. Traditional design lags behind the advanced product & process technologies available today. 5. Traditional design methods cannot cope with competitive requirements of the modern world. Due to the above reasons modern design problem cannot be handled by traditional methods. • Design by Innovation Since the traditional design method failed to cope with modern design requirements, nowadays almost all designs are made by innovation. i.e., developments of a product by following scientific and purposeful effort. The innovative design is entirely different from the past practice of evolutionary design. Here the designer's task is greatly magnified. He has to design and create something, which did not exist yet. Here he tries to solve the design problem in a systematic and orderly manner. This approach is similar to analytical problem solving. However, an innovative designer faces the following difficulties. 1. He has to collect and evaluate information on a product, which is non-existing yet. 2. Necessity of analyzing complicated interaction of components. 3. He has to make predictions regarding its performance.
  14. 14. 4. He has to ensure the technical and economical feasibility of the product. Notwithstanding the above difficulties, there are eminent experts like Morris Asimow, J.E. Shigly, Dieter etc have attempted to systematize the design process. This systematized steps in design process is called Morphology of Design . The best way in which any problem can be solved is to break up the problem and to try for a solution in an analytical method. This approach of problem solving is also adopted in the Morphology of design. 3.4. Problem-solving Methodology Knowingly or unknowingly we follow six basic actions when we try to find solution of any problem. 1. Establish or convince ourselves that there ‘is' a problem. Or we understand that a solution is needed. 2. Plan how to solve this problem 3. By analyzing the problem we decide what is actually required from the problem-solver. Or we decide the requirements. 4. Generate alternative solutions. 5. Evaluate the alternatives. 6. Present the acceptable solution. 3.5. Morphology of Design. Morphology means ‘a study of form or structure'. Morphology of design refers to the time based sequencing of design operations. It is a methodology of design by which ideas about things are converted into physical objects. The logical order of different activities or phases in a design project is called the morphology of design. 3.6. Design Process- Simplified Approach A simplified approach to designing as outlined by Morris Asimow is given below. According to him the entire design process in its basic forms consists of five basic elements as given below.
  15. 15. Design operations imply the various processes done during designing. These include • Searching for possible alternatives systems to satisfy a need. • Formulating a model for analysis purpose. • Materials selection, etc. But in order to carryout the above processes (i.e., design operations) a lot of information is required. The required informations may be broadly classified into two. 1. General Information E.g. Scientific Laws Information on market trends etc. 2 . Specific information . E.g. Information on manufacturer's catalogue Materials science handbook etc. Once the designer has obtained the necessary information he can start design operations. The design operations give outcome s. The outcome may be in the form of Computer print outs, or drawings.
  16. 16. Next stage is the evaluation of this outcome. The purpose of evaluation is to decide whether this outcome is able to meet the need. Here a comparison between the capabilities of the outcome and the need is carried out. If the outcome is sufficient to meet the need, the designer goes on to next step, otherwise the design operation is repeated 3.7 Detailed Morphology of Design A design project goes through a number of time phases. Morphology of design refers to the collection of these time phases. The morphology of design as put forward by Morris Asimow can be elaborated as given below. It consists of seven phases. Phase 1. Feasibility Study. This stage is also called conceptual design. A design project always begins with a feasibility study. The purpose and activities during feasibility study are • To ascertain there really exists a need [ie the existence of need must be supported by necessary evidences, rather than the outcome of one's fancy] • Search for a number of possible solutions • Evaluate the solutions i.e. is it physically realisable? Is it economically worthwhile? Is it within our financial capacity? Phase 2 Preliminary (Embodiment) Design. This is the stage art which the concept generated in the feasibility study is carefully developed. The important activities done at this stage are: • Model building & testing • Study the advantages and disadvantages of different solutions. • Check for performance, quality strength, aesthetics etc.
  17. 17. Phase III: Detail Design Its purpose is to furnish the complete engineering description of the tested product. The arrangement, from, dimensions, tolerances and surface properties of all individual parts are determined. Also, the materials to be used and the manufacturing process to be adopted etc. are decided. Finally, complete prototype is tested. Phase IV: Planning for manufacture This phase includes all the production planning and control activities necessary for the manufacture of the product. The main tasks at this phase are • Preparation of process sheet, i.e. the document containing a sequential list of manufacturing processes. • Specify the condition of row materials. • Specify tools & machine requirements. • Estimation of production cost.
  18. 18. • Specify the requirement in the plant. • Planning QC systems. • Planning for production control. • Planning for information flow system etc. Phase V: Planning for Distribution The economic success of a design depends on the skill exercised in marketing. Hence, this phase aims at planning an effective distribution system. Different activities of this phase are • Designing the packing of the product. • Planning effective and economic warehousing systems. • Planning advertisement techniques • Designing the product for effective distribution in the prevailing conditions. Phase VI Planning for Consumption/use The purpose of this phase is to incorporate in the design all necessary user- oriented features. The various steps are • Design for maintenance • Design for reliability • Design for convenience in use • Design for aesthetic features • Design for prolonged life • Design for product improvement on the basis of service data. Phase VII: Planning for Retirement. This is the phase that takes into account when the product has reached the end of useful life. A product may retire when • It does not function properly • Another competitive design emerges • Changes of taste or fashion The various steps in this phase are
  19. 19. • Design for several levels of use • Design to reduce the rate of obsolescence. • Examine service-terminated products to obtain useful information. 3.8. Methods of Innovative Design As we know, innovative design is an organized, systematized and logical approach for solving a design problem. There are two design methods for innovative design. • Design by creative design route • Engineering Design • Design by creative routs [Creative Design] This is a design method that demands maximum ‘creativity' from the part of the designer. Hence this method is also called creative design. Here the designer finds solutions to problems by allowing his creativity aspects grow in a particular manner. Creativity [S94, W95, W98, S03] Majority of designs belong to variant design, where the designer simply modifies an existing system. But the success of engineering design depends on the modes of thinking and acting distinctively different from others. A creative designer is distinguished by his ability to synthesize new combinations of ideas and concepts into meaningful and useful forms. Design is commonly thought of as a creative process involving the use of imagination and lateral thinking to create new and different products. Qualities of a creative designer [S96, S00, S03] The creative designer is generally a person of average intelligence, a visualiser, a hard worker and a constructive non-conformist with average knowledge about the problem at hand. Generally, a creative designer has the following qualities. • Visualization ability. Creative designers have good ability to visualize, to generate and manipulate visual images in their heads. • Knowledge All designers start their job with what they know. During designing, they make minor modifications of what they already know –or, creative designers create new ideas out of bits of old designs they had seen in the past. Hence, they must have knowledge of past designs. • Ability to manipulate knowledge
  20. 20. The ability to use the same knowledge in a different way is also an important quality of a designer. • Risk taking A person who does not take the risk of making mistakes cannot become a good designer. For example, Edison tried hundreds of different light bulb designs before he found the carbon filament. • Non-conformist There are two types of non-conformists:-constructive and obstructive. Constructive non-conformists are those who take a firm stand, because they think they are right. Obstructive non-conformists are those who take a stand just to have an opposing view. The constructive non-conformists might generate a good idea. But the obstructive non-conformists will only slow down the design process. Creative designers are constructive non-conformists, and they want to do things in their own way. • Technique Creative designers have more than one approach to problem solving. They are prepared to try alternative techniques, till they reach a satisfactory solution. • Motivation They always motivate others in the design team. In such a favourable environment creativity is further enhanced. • Willingness to practice Creativity comes with practice. Creative designers are ready to practice for a long enough period. Roadblocks to Creativity • Fear of making a mistake • Unwillingness to think and act in a way other than the accepted norm. • Desire to conform to standard solutions. • Unwillingness to try new approaches • Fear of criticism • Lack of knowledge • Overconfidence due to past experience • Unwillingness to reject old solutions • Fear of authority
  21. 21. • Difficulty in visualization • Inability to distinguish between cause and effect • Inability to collect complete information • Unwillingness to be different Methods to enhance Creativity • Use of analogy • Asking question from different view points • Memories of past designs • Competitive products • Deliberate day-dreaming • Reading science fictions, etc. Intuition [S'01] Intuition means sudden ideas or flashes of inspiration and involves complex associations of ideas, elaborated in subconscious mind. Intuitive ideas lead to a large number of good and even excellent solutions. Creative Design Route [W95, 94, 98, 9'00] Creative design route is the procedure through which a creative design is born. The success of this design lies with the creativity of the designer. Creative design route can be practiced by following the sequences shown in figure. During preparation period, the designer analyses the need and collect all the necessary information required at various stages.
  22. 22. Concentration is the period when the designer digests all the aspects of the problem situation and tries various possible combinations. The next step is the incubation period. The designer relaxes away from the problem for some time. Illumination is the sudden insight and throwing up with a solution. The final step is the verification. Now, testing and inspection of the design is done and the details are completed. For a designer using creative methods for design, habitual or familiar methods must be avoided. (ii) ENGINEERING DESIGN (W 96) Another procedure for obtaining innovative design is Engg. Design. Apart from creativity-approach, this is a logical and intellectual attempt to solve design problems. It largely depends on discoveries and laws of science. The different steps in Engg. design process is given below: - Recognition of need Definition of the problem
  23. 23. Gathering of Information Conceptualization Evaluation of concepts Communication of the design Since all design projects are meant for satisfying some need, any design work starts withRecognition of the need . The need for a design is initiated by either a market requirement, the development of a new technology or the desire to improve an existing product. Once the need has identified, the next step is to define the design problem . This is the most critical step in the design process. The definition of the problem expresses as specifically as possible, what the design is intended to accomplish. It should include objectives and goals, definitions of any special technical terms, the constraints on the design and the criteria that will be used to evaluate the designs. The success of a design project depends on the clarity in the definition of the problem. Need Analysis is the technique used to define the problem(Chapter 6). The next step is collecting information. In many phases of deign process a large quantity of information may be required. The required information can be obtained from textbooks, journals, or other agencies (See Art. 6.4) The conceptualization step involves, finding several design ideas to meet the given need. Inventiveness and creating is very important in this step. The different ideas conceived are weighted and judged in the evaluation step. The advantages and disadvantages of each idea against its performance, cost aesthetics etc is valued. After evaluation, the best design is emerged. This final design with every detail is furnished in last step- ie communicating the design.
  24. 24. Common features between Creative Design & Engg. Design (W.94) • The preparation phase in creative design and need analysis in Engg. Design is more or less common. Both steps deal with analyzing the need. • In both design methods brainstorming and Synetics can be applied. • Reviewing is applicable in both design methods. • For both deigns, the success depends on the clarity with which the need statement is prepared. • Testing and inspection is applicable for both designs. Difference between Creative Designs & Engg, Designs (W 94) • Intelligence is not a must for creative design-but the same is desirable in Engg. Design. • Creative design is based on use of analogy and synthesis of alternatives – but engineering design is based on proven laws and past experience. • Creative design involves phases like incubation, illumination – but no such philosophy is followed in engineering designs. • Creative person is highly intuitive and independent in thinking and usually resists working in group – but engineering designers like teamwork. • Customs, habits and traditions are enemies of creativity – but the same are required in engineering design. 3.9. Divergence, Transformation & Convergence (S'97 5M) The entire design process can be said to have composed of three distinct phases Viz. Divergence, Transformation and Convergence phases. The problem definition, need analysis and conceptualization etc. aims at generating as many ideas as possible to solve a given design problem. Thus, these activities belong to the Divergence phase. That activity wherein the concept is converted into physical object is termed as transformation phase. The convergence is a narrowing process, where the best optimal solution is tried for, by eliminating unwanted ideas. 3.10. Design Process Using Advanced Technology (W”00) Although Engineering is a major sector of the economy in a developing country. It has not been benefited greatly from advances in computer technology. Engineers still use computers only in peripheral tasks, such as drafting and analyzing, but not in making fundamental design decisions. Current computer tools such as ‘computer-aided drafting' are restricted to the end of the design process and play no fundamental role in aiding design. It aids only in the final drafting of the specifications.
  25. 25. Computer-aided Design, (CAD) means a class of tools for crating drawing, or the physical description of the object. CAD systems have been sophisticated and 2D and 3D models are available. The CAD allows the designer to conceptualize objects more easily. The design process in CAD system consists of the following stages. • Geometric modeling • Analysis and optimization • Evaluation • Documentation and drafting. QUESTIONS • How can you explain the term design? Explain the process of mechanical design. Discuss the role of creativity in the designs process. (S94. 8M) • The mechanical design process normally has six stages and amongst them the three stage are ----- ----- - ------- (S99, S94, 1 M) • What is morphology of design? Explain the various steps with the help of block diagram (W.95) • The three stages of design are………… (W 96) • State the different phases that are involved in morphology of design (S.96) • Briefly discuss the concept of creativity as applicable for solving design problems (W 98. 6M) • What makes the design process tortuous? Explain (W 99, 6M) • The creative design process can be considered to be ……… (S93) • Discuss creativity and creative design. Use examples to explain. (W 95) • What do you understand by intuition (S 01) • Draw a flow-chart showing different stages of engineering design. Explain why some stages are repeated several times. (S.93.5M)
  26. 26. • What feedback loops provide information for the redesign of products and the productive systems. (W'93) • The process of design by evolution adopted by craftsman is a ………….. Ans. Slow process of design development (W'94) • With suitable examples, compare ‘Design by evolution' and ‘Design by innovation'. (S 96) • Enumerate the steps in Engg. Design process and explain (W'96) • Justify the statement with reasons ‘Modern design problems cannot be handled by traditional methods'. (S'97, W'98) • Good design requires both------ --------. Ans. Analysis and Synthesis. (S'93) • Define creative design routes. What are the stages of these routes, Explain these in brief. (S'00) • Explain the process involved in creativity. What are the various qualities of creative designer? Give the brief description of these. (S'00). • What do you mean by creative design routes. Write down the different statements about creativity and creative designers. (S'01) • Compare the design synthesis and design analysis. Explain the basics procedure of design synthesis giving suitable examples. (S '02). • What are the common features and differences between creative design activities and Engg? Design activities. Explain briefly with the help of examples. (W'94) • Discuss the divergence, transformation, and convergence phases in the design of a new product. (S'97) • What are the three different stages in the design process? Explain with example. (W'99) • What are the most important steps involved in the design process? Explain? (W'00) • What are the methods currently being adopted for design process using advanced technology? (W'00) • Name various phases in design morphology. Explain these in brief. (S'01) • Explain Engg. Design (S'01) • What major steps are involved in design process? Briefly explain each one (W'01). • What do you understand by the design process? List out the various phases involved and explain them briefly. (S'02)
  27. 27. • Give the checklist for an engg. Design problem. (W'98) • ___ is one of the most powerful aids to creativity in design. (Use of analogy) (W '94). • What do you understand by the term “creativity”? What are its requirements? ('03). • Discuss the stages in engineering design process with the help of example. (S 05) • Explain ‘Design processes. Illustrate the steps followed with the help of a figure. Also explain the flow of work during the design process. (W 05, 8M) • What do you understand by ‘morphology of design'? Discuss the phases of feasibility study, preliminary design and detailed design. (W '05. 8M)
  28. 28. CHAPTER 4 IDENTIFICATION OF NEED 4.1. What is a need? A need can be defined as a personnel unfulfilled vacancy which determines and organizes all psychological and behavioral activities in the direction of fulfilling the vacancy A product can be product and marketed only if it is ‘needed' by the customer. A person buys a pen because he ‘needs' to write. A patient ‘needs' something that can cure his illness. These examples show that needs are nothing but a scarcity or problem or wants felt by a person, device or a system. In fact a designer's goal is to find solutions to such problems 4.2. Hierarchy of Human needs (W' 96) Maslow developed a hierarchy of human needs as given below 1. Physiological needs - These are the basic needs of the body- For example, thirst, hunger, sex, sleep etc. 2. Safety and security needs For a person whose physiological needs are met, the new emerging needs are safety needs. These include, protection against danger, threat etc. 3. Social needs Once the physiological and safety needs are met, the next dominant need is social need. For example he/she want to love and be loved, he want to be “in group”, etc. 4. Psychological needs These are the needs for self-respect and self- esteem, and for recognition. 5. Self-fulfillment needs These are the needs for the realisation of one's full potential through self-development, creativity, and self-expression. 4.3. Identification/Recognition of Needs (W 96) The beginning of any design process is the recognition of need or problem. When a turner hears an awkward noise from some part of the lathe he identifies/ recognises a need. i.e. the lathe requires repair. When the sales personnel observes that their customers are always complaining of poor
  29. 29. performance of the products, a need to develop a better product is identified. Similarly, when the customers are unsatisfied with the present ‘model', a new need is recognised. Needs can be identified from, • Careful market analysis • Statements made by politicians from their observations • Interpretations of a community's requirements • Trends in other parts of the world 4.4. Variety of Needs [S'00] Following are the needs, which can generate ideas for the development of new products. (i). Variation of an existing product. This could be a change in a single or a few parameters of an existing product. Eg - Changing the length of a cylinder. -Changing the power of a motor, etc. • Improvements in the existing product. This implies the need to redesign some of the features of an existing product. Such needs can arise, when -Customers want a new feature or better performance than existing features -A vendor can no longer supply components or materials that had been used so far -Manufacturing or assembly departments identifies a quality improvement -Invention of a new technology that can be incorporated in the existing design. (iii) A change in production model Whenever the production model changes from job-shop to mass, a corresponding change in product design may be demanded. For example, there is more tendency to buy off-the shelf components for short-run products. Whatever may be the situation, a company has to identify or locate a need before the production of any device. This crucial step is called Recognition/ Identification of need. Examples:
  30. 30. 1. With the free-entry of Chinese products to Indian market, manufacturers in India recognize a need to sell their products at a lower price. 2. When a company observes that their products do not perform well, the company recognizes a need to re-design it. 4.5 Need Statement Once the need has recognized, the next step is to prepare the need statement. It is a general statement specifying the problem for which a solution is required. In other words-It is the objective of design, expressed in the form of a statement. Need Statement – Examples *S ‘93+ Give one need statement for each of the following Bicycle Voltage stabilizers Personnel Computer i). Bicycle: - The need statement for a bicycle could be “A device for a common person to travel reasonable distance comfortably with least effort” –“The initial cost should be low- and be as light as possible, have adequate life, be easy to maintain etc “ (ii). Voltage stabilizer “A solid state noiseless electrical device of adequate power rating to provide continuously an output at constant voltage, accepting the input power at varying voltage between the limits__and__volts “. The indications for input and output voltage levels may be provided. iii). Personnel Computer “A computing device to accept input data, manipulate it according to a set of instructions and provide the desired output on CRT and printer” Questions 1. List hierarchy of human needs that motivate individuals. [W'96] 2. Give one need statement for each of the following Bicycle (ii) Voltage stabilizer (iii) Personnel Computer [S'93] 3. Explain the steps involved in identification of a problem by a designer [S'96]
  31. 31. 4. Every product is made in response to……….of individual or society. Ans. needs [S'97] 5. Enumerate and explain variety of needs which can generate ideas for the Development of new product. [S'00]
  32. 32. CHAPTER 5 PRODUCT PLANNING 5.1 Introduction Once the top management of an organisation recognized a need to develop a product, it will go for product design, only if, - the purposed product will guarantee a handsome profit - the market conditions are favorable in respect of competition. - the necessary resources are available - the purposed design is worthwhile. 5.2 Feasibility Study. The starting point of a design project is a need. Once the need has been identified, the company has to ensure the worth of the project. Feasibility study is a preliminary analysis for making a decision regarding the design project, to be forwarded or not. If the feasibility study reveals that the proposed design project does not bring comfortable revenue, or the design demands huge investments beyond the capacity of the organisation, the project is dropped. 5.3 .Product Planning [S 01] Planning is the process used to develop a scheme for scheduling and committing the resources of time, money and people. A plan shows how a project will be initiated, organized, co-coordinated and monitored. A product plan is a decision-making as regards to the design and manufacture of a product, by considering the revenues from different products. For example assume that a company already manufacturing 3 products, say P 1 , P 2 and P 3 identifies a need to design a new product ‘N'. Owing to the design and manufacture of the new product, the production volume, and hence revenue from products P 1 , P 2 ,and P 3 may be affected (due to re-allocation of company resources such as raw materials, machineries). In this situation, the company has to decide a time-schedule for the design and manufacture of the new product. Such plan made by the management is called the product plan. It must contain the time-as well as resource allocation for each of the products. More over it will result in optimum and efficient use of resources. After the product plan in made, the management begins a project for a new product design. 5.4. Organisation Of Design Group The complexity of mechanical devices has grown rapidly over the last 200 years. For example Boeing 747 aircraft (which has over 50,000 components) required over 10 thousand persons' years of design time. Thousands of designers worked over a three-year period on the project. These show that, design work is generally done by a team or group. A design team may include thousands of design and manufacturing
  33. 33. engineers, material scientists, technicians, purchasing agents, drafters, and quality control specialists, all working over many years. The first phase in any design process is identification of needs. Needs may be identified by market survey, the desire to improve an existing product or even by the development of a technology. Since any design activity consumes company resources like money, people and equipments etc. –the planning of these resources is the next phase after need- identification. Planning means allocation of resources such as money, people etc. The first step in planning is to form a design team. 5.5. Members of Design Team Following is a list of individuals needed in a design team. Their titles may vary from company to company. 1. Design Engineer. This person is responsible for suggesting ideas for the proposed product. For that, he must clearly understand needs for the product as well as its engineering requirements. Hence, he must posses both creative and analytical skills. He must be an engineering graduate having vast experience in the particular product area. 2. Marketing Manager. He is responsible for success of the product in the market. He is a link between the product and the customer. He always sees “whether the customer like this product? 3. Manufacturing Engineer. He knows the best manufacturing process suitable for the production of the particular product. He can give advice on the various manufacturing processes available in the industry. 4. Detailer In many companies the design engineer is responsible for specification development, planning, conceptual design and the early stages of product design. The project is then turned over to detailers who finishes the details, develops manufacturing and assembly documents. 5. Drafter A drafter aids the design engineer and detailer by making drawing of the product. In many companies the detailer and the drafter are the same individual. 6. Technician. The technicians aid the design engineer in developing test-apparatus, performing experiments etc. 7. Materials Specialist.
  34. 34. In some products, the choice of the material is based on availability. In some other cases, a certain material is to be chosen according to some features of the product. Material specialist can give advice on properties of different materials. 8. Quality Control Specialist. A quality control specialist observes how well the product meets specifications. This inspection is done on finished products as well as raw materials purchased from vendors. 9. Industrial Engineer. Industrial designers are responsible for how a product looks and how well it interacts with customers. They generally have background in fine arts and in human factor analysis. 10. Assembly Manager. The assembly manager is responsible for putting the product together. Note that assembly process is an important aspect of product design. 11. Suppliers' Representative. As part of product development, the company may purchase components or sub-assemblies from out- sources. In that case, the representative of the supplier of the specified component must be included in the design team 5.6 Organisational Structure of Design Teams Since a design project requires individuals with different fields of expertise, they can be organised into different structures. Listed below are the five organisational structures. The number in the bracket shows the percentage of design projects that use that particular organisation structure. 1. Project matrix, (28%) It is an organisation structure having the features of project and matrix organisations. 2. Functional matrix (26%) It is another organisational structure obtained by combining functional as well as matrix organisations. 3. Balanced Matrix (16%) Here the project manager and functional manager work together. A project manager is assigned to oversee the project, and the responsibility and authority for completing the project rests with functional managers. 4. Project Team (16%)
  35. 35. A project manager is put in charge of a project team composed of a core group of personnels from several functional areas or groups assigned on a full time basis. 5. Functional Organisation (13%) Each project is assigned to a relevant functional area or group within a functional area. A functional area focuses on a single discipline. 5.7. Task Clarification [S 01] A project plan is a document that defines the tasks necessary to be completed during a design process. A project plan is used to keep the project under control. It helps the design team and management to know how the project is actually progressing. There are five steps to establish a plan. They are, • Identify the task • State the objective of each task • Estimate Personnel's, time, resources required. • Develop a sequence for these tasks. • Estimate product development cost. Step 1 Identify the tasks In the first step of the planning of the design project, the different tasks needed to bring the problem from its initial state to the final products are identified. The tasks are the activities to be performed during the design process. Given below is a list of tasks drafted by a design team, for the development of a certain product. a. Collect and evaluate customer requirements and competition scenario. b. Establish two concepts for product development. c. Develop final prototype. d. Test prototype No1 and select one design for finalisation. e. Redesign and produce proto type No2. f. Field test prototype No2. g. Complete production documentation.
  36. 36. h. Develop marketing plan. i. Develop quality control procedures. j. Prepare patent applications. k. Establish product appearance. l. Develop packaging. Step .2. State the objective for each task. Even though the tasks are initially identified, they need to be refined to ensure that the results of the activities are the stated objectives. For example, for the task No. (a) above, the objective is to collect information required for developing specification. Step 3: Estimate the Personnel, Time & other Resources Required. Completion of each of the tasks listed above will consume resources such as personnel, time etc. An estimate of the requirement of resources may look like: Task Personnel/time Collecting data Two market surveyors, two months Concept generation Two designers, two week. Step 4 Develop a Sequence for the tasks The next step is scheduling of tasks-the purpose is to ensure that each task is completed, before its result is needed. CPM is the best method to accomplish this. Step 5 Estimate Product Development Cost On the basis of the above steps, the costs for developing the product can be estimated. Normally design cost is only about 5% of manufacturing cost. The above plan developed in the early stage of the design has to be refined as the project progresses. Questions 1. Market research is necessary before starting the production of any product. (True) [S '97] 2. Write a short note on – Product planning and task classification. [S '01]