Q3: List various products, designs or projects likely to be designed by the three schemes below. Briefly explain why that scheme is suitable. (Eg. Quick and cheap to test) Linear Design Scheme Circular Design Scheme Parallel Design Scheme Q4. Describe two designs that you consider to fail in some cases of normal use. Item Main function Design Failure Suggested Improvement Cast iron drainage grate To allow water to enter pit but permit vehicles to pass over Large lengthwise slots allow bicycle wheel to fall in - for serious accident * Run slots at 90 degrees * Narrower or shorter slots * Use grid instead of (a) ............... ............... (b) ............... ............... Q5. For the following items, describe its main use (design function), then list other design issues that are more unusual, and ones that cannot be designed for. For example: A schoolbag is designed for carrying books and things and may also need to survive wet weather or hot sun, but not necessarily underwater use or being run over by a car. Item Main function Design Issues Impossible Design Issues Shopping trolley Walkman Telegraph pole Calculator
Design Process: Consider standards relating to the design process. For example, engineering drawings to AS 1100, Guide to managing product design, AS 3950 etc. Standard Keep in mind the standards relating to manufacture of the item or components used in it. For example, use standard metric thread sizes rather than your own. Generally, you should try to use standard sizes and methods of manufacture wherever possible. Quality: Compliance with quality accreditation requirements relevant. This may effect documentation of the design as well as manufacturing operations. Better than Australian Standards. There may be more stringent standards applied (Eg Financial institutions may set a more demanding building standard - such as increasing the number of wall ties between brick veneer and stud wall by 20%). Local councils may set there own standards beyond the usual ones and these may need to be checked. Companies may also keep their standard of work above the standards. A label like ‘Exceeds AS****’ would indicate this. Overseas standards. These may be needed if your design is not covered by Australian Standards, or where the product will be exported. Eg: Manufacturers of biomedical equipment for sale in the US must obtain FDA approval not only for the product but also for the manufacturing processes and records. 2.5 Review Questions Q1: Which of the following services is NOT done by the Australian Standards organisation? (a) Checking and revising information on equipment safety (b) Ensuring companies comply with the relevant Australian Standard (c) Selling design standards on different types of machinery (d) Defining for electrical appliances Q2: Select some Australian standards and name any regulatory authority in your area that would become involved if you: If you ... Regulatory Authorities Australian Standards (a) Designed a new carport (b) Needed 3 phase power to a factory (c) Had doubts about the safety of a machine (d) Burnt rubber tyres for an industrial heater.
Break even: The break even point is the number of items that need to be sold in order to repay the investment. For example: Whiz-Bang Pty Ltd makes a circuit for an electronically controlled slow combustion heater. It cost $60 000 to develop ready for production. Each unit costs $7.50. Hotshot Fires Pty Ltd buys them for $25. How many units need to be sold to cover the startup investment? $60 000 = 3429 units ($25.00-$7.50) In reality, break-even analysis can be more complex than this. Eg Not all the profit may go toward amortisation, costs may vary with quantity, there may be other uses for the circuit, cost differences between shifts, cost variations etc. 4.2 Economic Design Constraints Here are some pointers for keeping the cost of a manufactured product low: Keep the design simple Higher volumes are cheaper Minimise labour Use cheap materials Use standard components Use cheap manufacturing processes Keep to as few processes as possible Design for minimal costs after manufacture Avoid changes to the design once finalised 4.3 Design Checklist: Economic Factors The following for designing to save money are all competing against the pressure of safety, performance, appearance and reliability. They need to be read as follows: Without compromising on safety, performance, appearance or reliability ... Keep the design simple: Fewer parts, less moving parts, less motors or controlled mechanisms, smaller size. Don’t over-specify: Keep tolerances wide for easier production, trim down (sizes, welds, fasteners, components) minimise ratings, strengths, materials Higher volumes are cheaper: Aim for higher repetition, one type of design Minimise labour: Less assembly work, easier assembly, labour content as late as possible in the assembly (avoid having high value-added sub-assemblies sitting around, or scrapped by later mistakes)