Engineering Design Concepts, Drawings, Measurements and Marking Out

Section One Understanding Engineering Design

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TABLE OF CONTENTS SECTION ONE UNDERSTANDING ENGINEERING DESIGN Section Learning Objectives Page 4 Section Introduction Page 4 The Design Engineer Page 5 Design Process Page 10 Design Limitations Page 14 Design Verification Page 18 Section Summary Page 19

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SECTION 1 – UNDERSTANDING ENGINEERING DESIGN WHAT OUTCOME CAN YOU EXPECT FROM THIS SECTION? In this section you will learn about the basic concepts of engineering design. SECTION LEARNING OBJECTIVES On completion of this section you will learn:

What an engineering designer does About the engineering design process What some of the design limitations are that designers encounter About design verification

SECTION INTRODUCTION Engineering design is a process where products or components are designed to satisfy a need. The engineering design process itself is not involved in identifying the need, but a need is presented to designers/engineers to develop a solution. At times, engineering design also involves the design of the processes that are required to produce the products. In this section we look at the design engineer and the engineering design process.

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THE DESIGN ENGINEER A design engineer can specialised in one of several different disciplines including:

Electrical engineering Mechanical and manufacturing engineering Civil engineering Architectural engineers/Building engineers

In a design project it is the design engineer that leads the project team. The design engineer is distinguished from the designer/drafter by virtue of the fact that a design engineer sets the direction of the design effort. He/she works with industrial designers and marketing to develop the product concept and specifications, and directs the design effort from that point. Products are usually designed with input from a number of sources such as manufacturing, purchasing, tool making and so on. The design engineer may direct a team of designers to create the drawings necessary for prototyping and production, or in the case of buildings, for construction. However, with the introduction of advanced computer aided design (CAD), the design engineer may create some, of or all the drawings him/herself.

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ELECTRICAL ENGINEERS Electrical engineering encompasses electronic, computer systems, telecommunications, control and electrical power engineering. It is concerned with the way electrical energy is produced and used in homes, the community and industry. Electrical engineers design and build the systems and machines that generate, transmit, measure, control and use electrical energy essential to modern life.

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MECHANICAL AND MANUFACTURING ENGINEERING This area covers the design and manufacture of a great variety of products such as domestic appliances, industrial machinery, ships, aircraft, engines, pumps, compressors and turbines or complex systems such as the air-conditioning and ventilation systems of buildings. The mechanical area interlinks closely with other areas of engineering and applies knowledge of materials, energy and structures. Mechanical engineers often work for industry designing systems for machinery that generate power, make products, move things and help in building. They may also work in chemical processing, power generation, the automotive industry, and manufacturing, building services, the aeronautical industry, defence technology, food processing and public utilities. Mechanical engineering also includes the area of hydraulics and is involved with the design of new and improved ways of applying fluid control, so that machinery can operate smoothly and effectively with the least amount of pressure. Also included is pneumatics and this covers the use of air pressure to control machinery. For many industries, air is a much safer material to use because it is clean and can be used safely in flammable areas. It is practical to use pneumatics in food processing as it is much cleaner. It is also used for safety reasons in machines that process flammable substances such as petrol and paint. Thermodynamics deals with heat energy transfer and machinery that turns heat energy into mechanical power. Engineers in this field design, manage and improve machinery such as boilers and gas and steam turbine generators, and facilities like cooling towers, and heating or refrigerant systems.

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CIVIL ENGINEERING Civil engineers are concerned with all types of structures including dams, bridges, pipelines, roads, towers and buildings. They are responsible for the design and construction of all our transport systems, the design and management of our gas and water supply, sewerage systems, harbours, airports and railways. Civil Engineers plan, design and test the structures of private and public buildings and facilities. They are also involved in many environmental areas such as the assessment of the impact large scale projects have on the environment and the collection and treatment of sewage and industrial wastes, pollution control, environmental control and resource protection and management. A civil engineer will work from an architect's drawings and consider whether the chosen materials for a particular building will be strong enough to hold a structure of that height or design. At the same time they would also think about how the structure might affect its surroundings. It is the responsibility of the civil engineer to produce safe, economical and environmentally-sound structures.

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ARCHITECTURAL ENGINEERS (ALSO KNOWN AS BUILDING ENGINEERS) What differentiates architectural engineering as a separate and single, integrated field of study, compared to other engineering disciplines, is its multi-disciplined engineering approach. Through training in architecture, the architectural engineer seeks integration of building systems within an overall building design. Architectural engineering includes the design of building systems including heating, plumbing, fire protection, electrical, lighting, transportation, and structural systems.

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DESIGN PROCESS As the term might suggest, the ‘design process’ is the process engineers use to design products. There is a common ten step process that most engineers will go through when starting a design project. The ten steps include: Understanding the need Defining the problem Conducting research Narrowing the research Analysing design criteria Finding alternative solutions Analysing possible solutions Making a decision Presenting the product Communicating and selling the product

UNDERSTANDING THE NEED The engineers themselves often do not identify a need, but rather someone discovers a need and then presents that need to an engineer. The term ‘need’ in an engineering context often refers to desire or shortage of a good. Understanding the need is a basic

engineering design step.

DEFINING THE PROBLEM The need often relates to a problem. To solve this problem there is a need to design a product and therefore it is important that the engineer first defines the problem. Designing a product that may satisfy a need but not the underlying problem would be a waste of time.

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CONDUCTING RESEARCH To design a better solution a design engineer will spend a substantial amount of time doing research. Questions an engineer may ask could be:

Who else has this problem? Have there been papers, articles or publications written about the problem? Has someone else designed a solution? Is there any person(s) that can be interviewed to discuss the problem? If so who manufactures the current solution? Is there a need for a better solution? If so will people/consumers/companies pay more for a better solution?

The greater part of the initial research process will be to find where the information can be sourced. There may be several sources however the engineer would need to choose what is most relevant. Another common research method is ‘reverse engineering’. This is where an engineer will locate a similar product and proceed to dissect it to see how it is designed and made, and look where improvements can be made.

NARROWING THE RESEARCH

At this point there would be enough research information and the design engineer would have to condense the information into what is the most appropriate in the process of solving the problem and satisfying the need. The engineer may have collected information that could be used to develop designs that are too radical, expensive to design, or inefficient. This information would be set aside.

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ANALYSING DESIGN CRITERIA Criteria means ‘the standards, measures, or expectations used in making an evaluation and/or verification’. In this step this would mean that the engineers would need to consider product characteristics that have been established from experience, research, market studies, and customer preferences before coming up with solutions.

FINDING ALTERNATIVE SOLUTIONS In this step, a list of the possible solutions is made and the pros and cons of each solution are discussed. Engineers will sometimes create a checklist of characteristics of the possible solutions and decided what could be changed to better the final result. ‘Brainstorming’ is a great way to decide what is good about the solution and what could be changed to better the solution.

ANALYSING POSSIBLE SOLUTIONS The next obvious step is to analyse all possible alternative solutions to determine their potential in solving the problem. This is where some of the possible solutions are discarded. Using mathematical and key engineering principles, the engineer analyses the potential performance of the solution to determine if the solution is physically and economically possible.

MAKING A DECISION The decision making step can be either a simple step where there is an obvious choice or an extremely difficult one where there is no one perfect solution. At this stage the engineer must always have the design criteria in mind. Some solutions may look to be ideal but they do not meet the set criteria.

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PRESENTING THE PRODUCT Once a solution has been chosen the engineer must present the ideas to relevant parties. At this stage it is those that will develop drawings and specifications based on what the design engineer has provided. The design engineer may provide sketches, written narrative on the solution and/or verbally communicate the idea and details. The design engineer must have good communication skills to effectively get the idea across to the draftspersons/engineering technicians.

COMMUNICATING AND SELLING THE PRODUCT The final stage of the design process is to sell the design to the various stakeholders. This could be management or clients. The presentation would likely be reasonably detailed design drawings, possibly models or prototypes, specification sheets, presentation materials showing the features and benefits of the design and may go as far as a manufacturing cost analysis.

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DESIGN LIMITATIONS There are many factors that affect the design process and the design engineer must take these limitations into account when participating in a design project. These could include:

Available materials Manufacturing capabilities Cost Laws and regulations Standards Codes Specifications

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The design engineer must take into account the available materials when designing a product. This would include:

Is the material available locally or does it need to be sourced interstate or overseas? What is the cost of the material and is there a cheaper alternative? Can the manufacturing process work with this material or will it require new tooling and/or equipment?

The design of the product would need to match the capabilities of the manufacturing facilities or the ability to have the manufacturing facility tool up to the new design both physically and financially.

Is new tooling required to manufacture the new design? Is this new tooling available or is it specially made and if so at what cost? Will the new product design have a reasonable return on investment? Is there a need for training production staff?

Given an unlimited amount of money any design can be made but is it considered viable? The cost of the new product would include:

Cost of materials Cost of inventory Cost of production Cost of assembly Cost of packaging and shipping

All designs need to take these and many more factors into account. The cost of manufacturing a product may be too high which could not be recovered in its selling price.

Available Materials

Manufacturing Capabilities

Cost

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There are many laws and regulations associated with the design of virtually all products. Most relate to the health and safety of the workers and the general public. The product must be safe to make as well as safe in its final use. The environmental issues also need to be considered when developing a new product. This would include the process in which the product is made – is it environmentally safe. Are the materials chosen with sustainability in mind? Is the final products application a danger to the environment and if so, can the design be changed to lessen the environmental impact? There are laws and regulations that protect the environment against manufacturing processes and products that have an impact on the health and safety of the environment.

A ‘Standard’ is a published document, which sets out specifications and procedures designed to ensure that a material, product, method or service is fit for its purpose and consistently performs in the way it was intended. Here in Australia there are the ISO and the Australian Standards in which many design engineers must review and take into account when designing new products. These standards would cover areas such as:

Health and safety in designs International compatibility of products

If designing for the overseas market the designer must not only understand the standards associated with the design specific to that country but also their laws and regulations. There are also quality issues that need to be taken into account. ISO 9001 Quality Standards are used by most major manufacturing organisations. Of the many requirements of ISO 9001 standards one is ensuring that the design meets the specifications required by the customer.

Laws and Regulations

Standards

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In Australia there are numerous codes in place to assist the design in meeting certain design requirements especially in the areas of health and safety. A good example is the Plant Code of Practice established by Queensland in 2005. There are similar codes in the other states and territories. It is suggested that you review the part of the code that relates to designers. This can be found at http://www.deir.qld.gov.au/workplace/law/codes/index.htm#.U0N0UVcrfTo

The engineering designer should not design a product that is clearly outside the known specifications as set by the customer/client. Specifications set by the customer should not be looked upon as a limitation, but more of a guideline.

Codes

Specifications

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DESIGN VERIFICATION Many designs, especially those that may pose a critical health and safety risk are verified before being released for general production, fabrication or manufacturing. Many times this would involve a professional ‘design verifier’. A design verifier refers to a person who has acquired by qualifications or design experience the knowledge and skills to accurately state that the design or part of the design for which a design verification statement is to be made, complies with a particular technical standard or engineering principles. Engineering principles are relatively different for each specific engineering discipline. For instance in structural engineering the engineering principles include areas such as strength, stiffness and stability of the structure when under load. Material choices and design need to take these into account. Design verification can include:

assessing if the design complies with the Australian Standards ensuring compliance and conformance with the specifications verifying the design to take into account all matters that are important to safety ensuring that the designer has not made unsupportable assumptions or applied incorrect logic

Design verification can be at one or several stages of the design project. It can be at:

the detail drawing stage – all drawings are checked and verified (at this stage it may be subject to a verifiable model). Drawings are checked for proper calculations, measurements, notes and so on.

modelling stage – the modelling stage may be where a scaled down model is produced to verify certain characteristics of the product before going into production.

prototype stage – this may replace the modelling stage where an actual full scale prototype is produced.

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SECTION SUMMARY Engineering design is one of the most important steps in most industries. Without proper designs buildings would not be built, airplanes would not be flying, there wouldn’t be any cars on the road and bridges over water wouldn’t exist. There are various stages to engineering design. We looked at the start of a design project, likely handled by a professional engineer or a qualified engineering technologist. Below these positions is generally what is called the design draftsperson. These persons interpret the design and draw the detail drawings for production. In the next sections we look at the engineering drafting and the components of engineering drawings.

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SELF ASSESSMENT At the end of each section you, the student, are asked a series of YES and NO questions. If any question is unclear our you have answered NO, then you are encouraged to review the materials in that section again. SECTION ONE THE DESIGN ENGINEER Do you know how the engineering design process is different in the following sectors;

Electrical Engineering? Mechanical and Manufacturing Engineering? Civil Engineering? Architectural Engineering?

DESIGN PROCESS Can you recall how a design engineer will conduct research on a project, and how would the final design be presented for consideration? DESIGN LIMITATIONS Are you able to understand what is involved in the following factors that affect the design process;

Available materials? Cost? Standards? Specifications?

DESIGN VERIFICATION Do you remember at what stages of a project, design verification can occur?

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STUDENT NOTES