As it can be expensive, extensive machining of a product is limited to trials or low volume products. It should be kept to a minimum for high volume products and so is not used for most consumer items. Industrially, milling, turning and drilling are often combined in CNC machining centres which can produce a wide variety of shapes at high speeds. These machines can contain over 200 different cutting tools, which are automatically replaced as they wear out.
It is possible (but unusual) to machine polymers – care must be taken as they can melt. In addition, machining polymers usually leaves a rough finish (they are normally smooth after moulding).
Mechanical cutting is a type of "machining" used to separate parts – the most commonly know processes are saws.