edaor
Want a Challenge?
It may seem surprising for the Director o f a Footwear Research Institute to be writing the editorial for a journal concerned with materials in engineering - even if SATRA (The Shoe and Allied Trades' Research Association) is the largest o f its kind in the world. By way o f explanation, however, is there any product other than footwear that: involves a knowledge o f so many different materials. Soles, for example, can be made from at least 500 different materials and polymer combinations takes so many processes to make varying from 60-120 for 'normal' shoes. is made in such small runs - average less than 200 pairs o f given size and style in all materials and colours sells as cheaply as a pair o f shoes even now? Concorde can beat the first three
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items, but it doesn't do too well on the last/ A f e w years ago, Sir leuan Maddock, then Chief Scientist in the Department o f Industry, suggested that there were four industries vital to life: food, clothing, housing and transport - and we wouM as a nation be ill advised to opt out o f any o f them. Certainly the European apparel industries and their associated supply industries employ about 1 in 6 people in manufacturing industry. Protectionist arguments and counter arguments abound. A t the CBI Conference in November, Consumer Association leaflets were handed out condemning the multifibre agreement on textiles. The consumers, it was argued, paid the cost o f protection through limited choice and higher prices. The leaflet also stated that in the USA it cost a calculated $13,000 per job saved in higher prices. In discussion last year with officials in Washington, it was claimed that this might indeed be the case, if only one industry say footwear, was considered. By the end o f the century, however, over 100 industries could be facing similar survival threats in the USA - I wonder if your industry is one o f them? It is interesting to note that, in the last 3½ years the UK lost to imports a larger share o f its home car market than it lost o f the footwear market in the last decade/ This, however, is not the place to develop international trade debates too deeply. I wouM like to question, therefore, the apparent glamour o f machinery engineering research as opposed to materials engineering research and suggest that we may not be getting our national priorities
right. I f the cost structure o f many manufactured products (including such diverse items as ear brake linings and shoes) is broken down, it is noticeable that the material costs are often about half the total costs, whereas the cost o f the machinery required to make the article is often less than 10%. In shoes, for example, machinery costs are only about 3% o f the ex-factory price while materials account for about 45%. Other things being equal,
Cross section of the topmost layers of Clarino F. Shows the coarse and very fine fibrous structure of the polyurethane matrix; note the very thin (about 5 micrometers) surface coating which provides resistance to penetration by water but allows a good degree of water vapour permeability. A unique feature of this material is the microfibrous nature of the individual nylon fibres seen clearly in this picture; this makes for softness and flexibility in the material.
MATERIALS IN ENGINEERING, Vol. 2, MARCH 1981
or4al & terms o f wealth creation we wouM be much better o f f developing and selling internationally competitive materials for shoes than the machinery required to make them. Ideally, o f course, we shouM compete internationally with the whole product, but this can be very difficult when competing with countries with very much lower labour costs. It is perhaps salutary and regrettable that the Japanese and our EEC competitors have developed the new types o f polymer-based materials more quickly and often more successfully than we have in the UK. I conclude with a market and technical challenge. The UK market for polymers for shoe materials and components is
about £100m per annum. The developed world market is approximately £2,000m per annum and the total market approximately £3, O00m. Certainly the world market is there, large, permanent and growing. On the technical side, look at the challenge o f man-made "leather" for shoe uppers. UNIDO estimate world leather demand will have grown by 8% by 1985, while world leather production will have grown by only 4% during the same period. Look at the stereoscan micrographs below. The left hand photograph is o f leather. The right hand photograph shows one o f the most sophisticated man-made shoe upper materials, Clarino F.
Cross section of side leather. The grain layer is the dense, top 20%; hair follicles and residual hair can be seen in this layer. Below the grain, coarser horizontally orientated fibres occur and lead into the large fibre bundles of the corium. Note the angled weave of the latter. Thickness is about 1.8ram.
MATERIALS IN ENGINEERING, Vol. 2, MARCH 1981
To balance the requirements o f permeability to sweat with scuff-proofness and water-proofness; to create a finely wrinkled surface on an inward fold and a pleasantly rounded top on an outward foM; to have excellent resistance to chemical degradation while offering a wide range o f surface effects from suede via anilines to shiny patents; to give excellent adhesion to soling materials with high tear strength while retaining just the right blend o f softness and plasticity are examples o f the exciting challenges that are encompassed within the field o f materials in engineering. Let us not hand all these developments to our overseas competitors.
J.G. BUTLIN
Cross section of the artificial leather Clarino F. Note the open, porous structure and, unusually for this type of material, the coarse cellular structure in the top coating layer (corresponds to the grain in the side leather). The material which is about 1.5mm thick, has good permeability to water vapour, an essential feature for men's and children's footwear.
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