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Introducing engineering
Introducing engineering

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2.6.3 Industrial design

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Figure 32 Industrial design, provides appearance and user interface
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Figure 33 Engineering design, provides function

The term 'industrial design' is often used to denote those design activities mainly concerned with the appearance and aesthetics of a product as illustrated in Figure 32. In contrast the term 'engineering design' is often used narrowly to indicate those design activities that deliver the physical performance of the product as shown in Figure 33. Thus, for example, the engineering design of an iPad is about the electronics and software. The industrial design is about the appearance of the case and interaction with the functions of the device through visual and touch interfaces.

In some cases the technical issues of engineering design can be separated from the issues of industrial design. This is particularly the case with mature products where functional development is limited by the technology. The functional parts of these products can be clothed in a new aesthetic.

Activity 15 (exploratory)

  • a.Think of an example of a design where a new appearance for a product was created but the underlying function remained unchanged. By underlying function I mean either the technological principle of its operation (how it works – internal combustion engine for cars) or what the design does for a user (cars provide a flexible means of transport).
  • b.Think of an example the other way round where the way a product worked changed radically but its appearance or more broadly, the way people interact with it, remained largely unchanged. You might like to consider how cars or computer data storage can illustrate these cases, but please explore more widely.


  • a.Hatchback car as variant of the four door saloon car, plastic kettle replacing aluminium or stainless steel.
  • b.Hybrid car with electric drive, whilst car retains appearance, or memory chip storage replacing hard disk storage.

The judgements that designers and consumers make about the balance of appearance and function are subjective. That is, people make their own judgements about this balance, which can differ widely from individual to individual.

Designed products can be seen and thought about in many ways. They are invested with 'life' and meaning by people who use them. This extra meaning, for example in the fashion status of functional products (such as catering equipment now popular in domestic kitchens), is one of the key elements in a successful product. Designed objects acquire many layers of meaning. The process often starts with designers themselves and is continued by advertising. This interpretation is what people do well. In fact it is one of the important activities in designing where new possibilities for developing partially completed designs emerge. The design evolves and adapts as the designer sees and thinks in different ways.

Designs are not just differentiated by what they do and how they do it, or what they look like, but also by the wider social and economic contexts in which they are created and used. Other contexts for design might include the ways an industry is structured, its markets or even politics. Let us look at the aircraft industry, which includes airframe designers such as Boeing or Airbus and engine designers such as Rolls-Royce or General Electric.

In the aircraft industry the life of a design and its variants is of the order of 40 or 50 years. Rolls-Royce maintains a full range of jet engines, some used in aircraft built in the 1970s. There are a number of key technologies, business relationships and supplier industries who come together to make an aircraft: electrical and hydraulic systems, structures, materials, aerodynamics and engines. Figure 34 shows the dominating design requirements at different points in the airframe.

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Figure 34 Dominating design requirements for airframe

Fatigue (see Fatigue ) is a very important concept in designing for the operating life of a product. The extent to which fatigue will occur in a particular design depends on how the product is used – the operating conditions. Detailed understanding of the long-term effects of this fatigue is difficult to predict without extensive testing. A lot of the knowledge gained about fatigue is empirical. It is case-by-case and material-by-material. Patterns do emerge but experience shows that they must be used with caution. For long lifetime products, such as aircraft, the ability to predict the effects of operating conditions is critical. I emphasise this because a lot of our perceptions of good engineering design hinges on quality and, more particularly, reliability and durability during the typical life cycle conditions.


Metal fatigue is an extremely common cause of material failure. Fatigue is a very subtle process, the onset of which can go unnoticed until the fatigued component fails. Fatigue can occur at stresses much below the strength of the material, so may cause failure in a condition that was originally considered safe by a designer.

Fatigue occurs when the stress in a component oscillates with time. If the oscillations are sufficiently great, they can lead to the initiation and growth of cracks within the material. These cracks can grow until the component fails, often quite catastrophically, Figure 35.

The existence of fatigue has been recognised for over 100 years, but it is only in recent decades that the process has been understood thoroughly to the point where it can be designed against successfully. Failures such as the loss of three Comet airliners in the 1950s, the Markham colliery disaster in 1973, the Hatfield rail crash in 2000 and the grounding of the fleet of A380s in 2012 were all caused by fatigue. The lessons learnt in each case mean that designers are progressively better equipped to prevent it occurring in future.

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Figure 35 Failure of a bicycle crank due to the growth of a fatigue crack

How are the design activities of airframe companies dependent on context? Let us have a look at materials development in the context of a company like Airbus. The industry is a user of advanced aluminium alloys because they are strong for their weight, as well as new composite materials. Associated with each material is a large body of knowledge on performance from tests and in-service data. To develop and use a new alloy or new composite is a significant commitment.

In the case of alloys, Airbus is interested in new aluminium–lithium alloy for use in airframes. Lithium is a light atom, so if an alloy can be developed with comparable properties to existing alloys, then it will reduce the weight of the airframe. The consequent effect to the airline in reduced operating costs or increasing payload could be a major commercial benefit. However, Airbus does not develop alloys. They are developed and promoted by alloy producers, so the product design company works closely with the metal design company, who also work with Airbus' competitors. The context of design becomes more and more intricate.

To add to this complexity, if a competitor such as Boeing is working on such an alloy then Airbus cannot afford not to parallel the work, even if they know that the prospects of success are remote. Designers in the different companies watch each other, not in the sense of industrial espionage, but in the open forums where companies that simultaneously compete and collaborate, meet. The same principle applies to aero-engine companies. A new alloy that will operate at higher temperatures makes a more efficient engine, so if General Electric is working on a new class of material then Rolls-Royce also has to work on this class.

The ways that these complex sets of interrelationships behave changes from business to business. In order to provide a contrast, compare the aerospace context with the design of packaging for household foodstuffs and cleaning products. Unilever and Proctor & Gamble compete fiercely in a global market for soap powder. They try out new packaging in test markets and watch each other's test markets carefully.

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Figure 36 Liquid clothes washing detergent capsules

Over the past 20 years many different delivery mechanisms for washing machine detergent have been introduced and superseded. Quite recently small soluble plastic flexible bags of liquid clothes washing detergent have been introduced to improve the delivery and dispersion of detergent through the washing load in domestic washing machines, Figure 36. These small bags of detergent are placed directly in the washing machine drum with the dirty clothes. They are sold in huge quantities worldwide and require a considerable design effort to equip factories with the new tooling to make the new packaging. However, this can be accomplished relatively quickly and the advantage to be gained in the market depends critically on the speed with which new designs of tooling, machines and manufacture of the new detergent packages and subsequent delivery to the market can be put in place. So 'design' operates quite differently in the world of washing detergent compared to the world of airframes. Designers of soap powder can try out possibilities in markets (and change quickly to respond to success and failure) but aircraft designers usually only get one shot.

Industrial and engineering design are not really quite so distinct as the discussion above might imply. I want to explore the commonalities. Think of industrial design as the design of those parts and aspects of a product that are concerned with the ways that a product is used – how users interact with it. A car steering wheel and associated controls can be viewed as the interface to the mechanical and electrical functions. The design of these controls is surely about appearance and feel but their layout, usability and clarity contributes to the essential engineering function of the car. There is no point in having a great new engineering design of a 'powertrain' (engine and transmission) without the driver being able to take full advantage of it. Industrial design meets engineering design. In order to deliver good industrial design, engineering design skills are employed and vice versa. For the car controls, designing a control switch that 'feels right' requires suitable material, size and structure to deliver the right strength and stiffness, as well as attributes of shape, colour and texture.

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Figure 37 John Harrison and his time piece

To conclude these reflections about the nature of design and innovation on a lighter note, let's touch on a famous design case study from the history of navigation. Clocks in the 1700s only worked accurately if their mechanisms were kept still on the mantelpiece. But clocks were needed to tell the time at sea for the determination of longitude. Valuable prizes were offered for a solution and eventually a satisfactory design was created by John Harrison (Figure 37). The story of this design and its social, political and economic contexts is related by Dava Sobel (2005) in her book Longitude.

The new design certainly met a need. There were numerous innovations in the internal clock mechanism to achieve the accuracy that was required. But the design did not behave in new ways – it still counted the seconds mechanically. The matching of design and operating conditions was the key to success; the design of the marine chronometer allowed the mechanisms of the clock to work independently of the disturbances of a voyage at sea. Clever design of the clock mechanism decoupled the internal function from external context.

Design is complex and there are many ways to handle this complexity. We have seen in this section so far how design problems are commonly broken down into stages of increasing detail and definition. There are many activities in the process of design, and these are used in different mixes and with different emphasis according to context. The various ways that designers approach complex problems where there are no clear or even rational answers, under conditions of extreme uncertainty, makes design an exciting area of study. Design lies at the heart of engineering practice – it makes things that are useful, beautiful and, perhaps more often than it should, unsatisfactory. But that is what happens when we engage with complexity – surprise and disappointment, success and failure.