Industrial Materials
The industrial materials sector includes a broad array of companies, which make everything from the fragrances used in soap to bulldozers and heat-seeking missiles. The general business model is simple: Industrial materials companies buy raw materials and facilities to produce the inputs and machinery that other firms use to meet their customers' expected demand for goods.
We divide industrial materials into two groups: (1) basic materials such as commodity steel, aluminium, and chemicals and (2) value-added goods such as electrical equipment, heavy machinery, and some specialty chemicals. The primary difference is that commodity producers have little or no influence on the price of the products they produce. Makers of value-added industrial materials, on the other hand, may be specialized enough or improve a customer's business enough for the manufacturer to share part of that benefit in the form of a premium price.
Although basic materials industries do have significant barriers to entry – the cost of constructing a new steel, aluminium, or paper processing plant is steep – stiff price competition makes for mediocre profits at best.
http://books.danielhofstetter.com/the-five-rules-for-successful-stock-investing/