17.3 Choosing appropriate materials and manufacturing process
The choice of materials and manufacturing process for a particular new product is an important aspect of the innovation process. It is not necessarily the case that the materials chosen for the early prototypes of an invention are those best suited for the larger-scale manufacture of the innovation. Choice of materials can affect the performance, quality and economic manufacture of most new products, so it's important to choose wisely.
While inventors and designers usually need to seek specialist assistance when it comes to choosing materials, it helps to inform their choices if they have a broad overview of the main types of material and their properties. Designers need to consider a range of materials properties:
performance – behaviour of the material in the finished product;
processing – behaviour of the material during manufacture;
economic – cost and availability of material;
aesthetic – appearance and texture of processed material.
Increasingly environmental impacts are playing a part in the choice of materials. These impacts include the energy consumed and pollution produced in the extraction and preprocessing of raw materials as well as their final processing into a product; and the effect of chosen materials on the life of the product; the potential for recycling and environmentally sound disposal at the end of the product's life. With all these factors to consider it's not surprising the final choice of materials for a new product is often a compromise, strongly influenced by the costs both of the material itself and of processing it.
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In the same way that inventors and designers need knowledge of the range of materials available, they equally need to know the strengths and limitations of a range of manufacturing processes. As with the choice of suitable materials for a product there will often be a number of feasible processes. The following are the different criteria that can be applied to identify an optimum process in a particular case.
Cost – the capital cost of new equipment, the cost of dedicated tools such as moulds, the labour costs of setting up and operating the process, and the assumed rate of depreciation for tools and equipment.
Cycle time – how long it takes to process one item (part, component or product).
Product quality – the standards required in terms of performance properties, surface finish and dimensional tolerances, and maintaining quality over time.
Flexibility – how easy it is to produce different designs on the same equipment.
Materials utilisation – the amount of waste material generated during processing.
The relative importance of these criteria will vary depending on the volume to be produced and on whether the products will be identical or the same equipment will be used to manufacture different designs.
The ability to design and make a new product to the optimum quality specifications at the lowest cost and in the shortest time has been the general goal of manufacturers since the start of the industrial revolution. The means by which this goal has been achieved have developed as materials, techniques and the organisation of production have evolved. Not only has the transformation of the manufacturing process enabled many inventions of increasing complexity to reach the market and become successful innovations, the manufacturing process itself has been the subject of much innovation.
In a number of the examples earlier in this unit you've seen that the development of most innovations includes significant reductions in cost, which make the product affordable by larger numbers of customers. (Examples include the BIC ballpoint pen, Edison's electric light and the electronic tagging of products.) Often this cost breakthrough is due to decisions made in the area of materials and manufacture. A new material might be used in the product that makes it easier and cheaper to manufacture (the use of plastic for the bodies of ballpoint pens); a new assembly process might be more efficient with fewer components and fewer stages (recall that the assembly of Edison's electric light was reduced from 200 to 20 steps and the labour time from 1 hour to 20 seconds); a new manufacturing process might become applicable to the production of an innovation (fluidic self-assembly allowing production of RFID tags on an industrial scale).
Further savings might be achieved by regularly reviewing the design and manufacturing process for a product and aiming where possible for simplification and integration. Can the product be redesigned with fewer parts? Can parts be designed to serve more than one function? Can a new or different principle be used? Can parts be redesigned for ease of fabrication? Can fasteners be eliminated or reduced by using tabs or snap-fits? Can a product be designed to use standard components?
The basis of mass production is the complete interchangeability of components and the simplicity of attaching them to each other. With this increasing reliance on interchangeability in a world dependent on mass-produced products, it becomes more important than ever to know that products are being manufactured accurately to common standards and that their performance can be relied on.
Standards are another key component of the innovation process, providing guidance to the manufacturer on the expected quality and performance of a new product or process. And standards reassure the user that the product has been well tested before being launched onto the market. (See Section 3: 1.4.)