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AMI4900: Engineering Design

Unit 1: Commercial Overview

Section 3: Life cycle considerations

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Activity Solution

Some of the general ‘Design fors’ that you should take into account are:

• Design for reuse
• Design for recycling
• Design for disassembly
• Design for remanufacture
• Design for energy efficiency
• Design for compliance with regulations and standards
• Design to minimise impact on human health and safety

The selection of materials is always a trade-off of one factor against another – environmental issues introduce another range of issues that need to be considered:

• Ensure that the choice of materials is appropriate to the expected life of the product
• Use renewable materials from source where this is appropriate
  • From a long term view of sustainability renewable materials are of considerable interest (e.g. plastics that can be derived from biological sources). However, the concept that any renewable material is environmentally superior is a simplistic view. One of the key issues in environmental design is deciding which of the renewable materials are actually sustainable.
• Use recycled materials where possible
  • Metals have a strong tradition of recycling: steel and aluminium rely on recycled materials for their feed stocks; recycled aluminium consumes only 5% of the power needed to produce virgin material.
  • Recycled plastics are however still in their infancy, and tend to be used in ‘cascade’ products, materials ‘looking for a purpose’, or used for niche markets. Quality-assured recycled plastics are still not the norm, so that designers are unlikely to use them for cosmetic surfaces, although they can be used for hidden components
• Minimise use of hazardous material
• Avoid or minimise materials containing toxic materials
• Consider the energy implication of the choice over the lifetime of the product
• Use lighter-weight material (or less material)
  • Using less material has obvious economic benefits and can have substantial environmental benefits. For example, transportation benefits from fewer and lighter weight materials. As a result, packaging is constantly searching for methods of ‘light-weighting’: in the V8 saloon Audi replaced steel by aluminium, which reduced the weight of the structure by 40% and improved fuel consumption considerably.
• Eliminate surface finishes by using self-coloured materials.

The manufacturing process requires close interaction between the designer, production staff and components suppliers. Many production issues can be reduced through clean production techniques, and Design can also contribute by designing products for cleaner production.

• Minimise the variety of materials.
  • This has advantages both for overall business efficiency, by simplifying ordering and stock-keeping, often saving on waste materials, and for the environment, by simplifying recycling, with fewer materials to sort.
• Design to avoid materials wastage
• Reduce the number of components and assemblies by integrated function
• Design for simple assembly