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Selection of Components



1 Introduction

  • There are many factors that influence the way a product is designed and the components they use to make it.
  • A designer needs to understand these factors to be able to design a product that will:
    1. Appeal to the consumer.
    2. Be safe to use.
    3. Be cost effective to manufacture.

2 Aesthetic Factors

  • There are about how the product looks.


  • Form can be described as the overall shape, profile and or visual appearance of a product.
  • Products are often designed purely with form in mind e.g. fashion items like watches, shoes and bags.
  • Products like these, where form has dominated over function in the design, will have been designed with current fashions in mind and have a short lasting consumer appeal.


  • Colour is very much personal taste, however, designers use colour to help define the product’s function. For example television and audio equipment is often black/brushed steel, children’s toys make use of bright primary colours, safety equipment is often bright yellow/red.
  • Often colour is used to define a product that is intended to be used by male or female users.
  • Colour choice of key components on a product not only provide aesthetic appeal but also have ergonomic uses, for example lights in a car dashboard or a television remote control.


  • Designers use texture to enhance the shape of a product, where one part of the product may be gloss and another a smooth lightly textured finish to aid grip for the user.
  • For example a hairdryer might have the grip in a textured surface for ease of grip but gloss or chrome finishing for the main body to enhance appearance.
  • Clothing and footwear uses texture predominantly, it allows designers to accentuate aspects of the design.

3 Environmental Factors


Restriction of Hazardous Substance Directive

  • The Restriction of Hazardous Substances Directive (RoHS), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Union.
  • The RoHS 1 directive took effect on 1 July 2006, and is required to be enforced and became a law in each member state. This directive restricts (with exceptions) the use of ten hazardous materials in the manufacture of various types of electronic and electrical equipment. It is closely linked with the Waste Electrical and Electronic Equipment Directive (WEEE) which sets collection, recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of huge amounts of toxic electronic waste.
  • It is often referred to as the lead free directive.
  • Only the first 3 are mentioned in the specification.
    1. Lead (Pb)
    2. Mercury (Hg)
    3. Cadmium (Cd)
    4. Hexavalent chromium (Cr6+)
    5. Polybrominated biphenyls (PBB)
    6. Polybrominated diphenyl ether (PBDE)
    7. Bis(2-ethylhexyl) phthalate (DEHP)
    8. Butyl benzyl phthalate (BBP)
    9. Dibutyl phthalate (DBP)
    10. Diisobutyl phthalate (DIBP)
  • All of the above substances are toxic to plants and animales and are severly restricted.
  • In electronics, we use solder wire which is a mixture of Tin and LEAD, this means the we need to consider the use of solder in our products.
  • There are other options, including lead free solder which could be used as a substite, depending on the circumstance.

Waste Electrical and Electronic Equipment Directive (WEEE)

  • The Waste Electrical and Electronic Equipment Directive (WEEE Directive) is the European Community Directive on waste electrical and electronic equipment (WEEE) which, together with the RoHS Directive, became European Law in February 2003. The WEEE Directive set collection, recycling and recovery targets for all types of electrical goods, with a minimum rate of 4 kilograms per head of population per annum recovered for recycling by 2009. The RoHS Directive set restrictions upon European manufacturers as to the material content of new electronic equipment placed on the market.
  • The symbol adopted by the European Council to represent waste electrical and electronic equipment comprises a crossed-out wheelie bin with or without a single black line underneath the symbol. The black line indicates that goods have been placed on the market after 2005, when the Directive came into force. Goods without the black line were manufactured between 2002 and 2005. In such instances, these are treated as "historic WEEE" and falls outside reimbursement via producer compliance schemes.


  • The WEEE directive covers any product that has a plug or battery.
  • About 2 million tonnes of WEEE is scrapped every year in the UK alone.
  • Fridges used to contain a gas called Freon which is extremely bad for the environment, after being released into the atmosphere, it harmed and depleted the Ozone layer.
  • This coolant is no longer used, instead we now use R-600a, or isobutane which is far less harmful to the environment.
  • However old fridges will still contain Freon and will need to be disposed of properly.
  • Old Flourescent tubes (light bulbs) contained Mercury and would need to be disposed of correctly. Mercury in the water system is extremely hazardous.

4 Availability Factors


Use of stock materials

  • Materials are processed and sold in standard sizes, called stock materials.
  • For example, we use 3mm Laser Ply and Acrylic that has been precut to 600X300mm.
  • This allows us to easily design our parts to fit into the standard size.
  • The down side is that if we wanted a specific size, we are unlikely to get it. For example we can not purchase 5.2mm thick acrylic.
  • Electronic components also come in standard sizes. Resistors have specific values and ranges.

Use of specialist materials

  • Electronic products often contain specialist materials and components.
  • This can make manufacturing more difficult.
  • You will need to consider this when designing a product as the specialist part/components will be more expensive and might not be readily or easily available.
  • If the supplier runs out of the product, your production will come to a halt.

Use of scarce elements

  • Electronic products contain a lot of rare earth elements, particularly within rechargeable batteries.
  • As a manufacturer, you will need a reliable source of materials and components, if they run out, your production will halt.
  • For example, the main producer of Lithium is Chile, if they stop production due to political turmoil this will have a serious implact on prices and supply and therefore you company.

5 Cost Factors


Quality of components

  • No product can be made perfectly, all products will have a degree of imperfection. This is called the tolerance.
  • The tolerance is the upper and lower limit within the manufacturer garuantees the product.
  • The more accurate/perfect a product needs to be, the longer a manufacturer needs to spend trying to ensure the product is a claso to perfect as possible. The more it will cost the consumer for this product.
  • When choosing a component in your designs, you need to consider how accurate you need to component to be as this will have a real impact on the cost of production.

Manufacturing processes necessary

  • When deciding to produce a product, the scale or number of products needed will determine the manufacturing process.
  • Small scale production with fewer products, usually in less than 100 would use a different process than manufacturing thousands.
  • This will determine the types of machines you use as well as the type of factory needed.
  • The setup costs of a large mass production factory will be significant and should be offset against the cost of the product to determine if it is viable.

6 Social Factors


Use for different social groups

  • You will need to decide a specific target market, different groups of people will have different interests as well as different priorities.
  • A well designed product might appeal to one group, but not another. It would be best to try involve as many groups as possible to braoden you opportunities.
  • This can be really challenging, for example, a computer with large keyboard button might suit one group more than other.

Trends and fashion

  • A manufacturer is always trying to keep their product desirable, this will involve keeping up with trends to ensure their products popularity.
  • This does not always mean the product will be successful, for example, 3D televisions were very trendy/desirable in recent time, but were not very successful as a product, with most manufacturers no longer sell 3D televisions.


  • Trying to measure the popularity of a product depends on many variables, how good it looks, how well it works, does it appeal to the consumer, has a celebrity endorsed it, etc.
  • A popular product does not always mean it is the best product available, it might be look good, but not work well.

7 Cultural and Ethical Factors


Avoiding offence

  • There are many cultural differences around the world, when designing a product, it is fairly straight forward that is people are offended by your product, they will not purchase it. However, you might not have considered all the cultural differences.
  • If you are going to sell a product country wide or even internationally, you will need to consider different cultures.
  • You will eed to try your best to avoid certain words, symbols or even pictures that might be offensive to different groups of people, including religions.

Suitability for intended market

  • When selling products to different countries, there are many different ways in which they do things, for example, many countries will use different plug sockets or even voltages.
  • You would not be able to sell your product in these coutries unless you can adapt it or sell an adaptor.
  • You will also need to consider the age group, small children can easily swallow small products and this would need to be thought out in your design.
  • Grandparents might not be interested in the same products teenagers would be interested in and the designs would need to change accordingly.

Use of colour and language

  • Colour of a product may not seem important as you may feel it is personal. However, in some cultures colours have more meaning than in other cultures.
  • For example, in Malaysia, Yellow is reserved for royalty. In China, red is considered a very lucky colour whereas, white is the colour of death.
  • Language is very important, the most spoken language in the world is Chinese, but it is mostly spoken in China, whereas Spanish is the second most spoken language and it is spoken in many different countries.
  • You need to ensure the product details and instructions a translated into the language for the country you wish to sell it in.

The consumer society

  • Most developed countries are consumer societies. As they are wealthier, products are considered as relatively cheap.
  • Most people are able to afford to purchase these which is good for the consumer. The down side is when this becomes too expensive and the consumer still wishes to purchase the products.
  • This could lead to borrowing and debt issues in the society.
  • Another potential risk is the using of environmental resources very quickly to produce these products, this will have a serious effect on the environment.

The effects of mass production

  • Mass production has been used well to supply products in high volumes to the consumer societies. This has kept the products cost down making them cheaper for consumers.
  • This has also led to factiry automation, which has then led to the replacement of jobs.
  • Jobs have also become more repetitive in the high speed production factories which is not always good for workers.
  • With machines doing large chunks of the work, fewer jobs are available. Instead there are small numbers of engineers and computer programmers to run machinery.

Built-in product obsolescence

  • Lots of products only have a short lifespan.
  • Manufacturers build in dates when the product will become obsolete, by updating software or no longer supplying parts. This forces consumers to buy new updated products.
  • The mobile phone industry is a good example of this, many phones come with batteries that can not be replaced without specialist equipment, so most consumers just throw the phone away when the battery no longer works and purchase a new one instead of just replacing the battery.
  • As mobile phone batteries are not long life components, this means that uses will regularly be purchasing new products.
  • This process of making products with a short lifespan is called built-in obsolescence.
  • This is a very environmentallly unfriendly way of manufacturing. This leads to a throw away society instead of repairing and reusing perfectly good products.

8 Recap



  • Products aesthetics are an important part of consumer appeal.
  • The RoHS and WEEE directives aim to keep hazardous substances that are used in products out of the environment.
  • Manufacturers prefer to use materials that are easily available and will use stock sizes where possible.
  • Different social groups have different needs and interests.

Practice Questions

  1. What do the words ergonomics and aesthetics mean?
  2. What is the purpose of the RoHS directive?
  3. Why is it important for a designer to have some understanding of the use of colours and language?
  4. Explain how built-in obsolescence could have an impact on the environment.