Process Encyclopaedia

Milling

Overview

Milling will be familiar to anyone with experience of a metal workshop. The machines used industrially can be extremely sophisticated - the cutting head is often able to twist and turn in many directions! As well as being used for many small products suitable for school workshops, milling has been used for large scale items such as aeroplane wings and tanks!

Materials and shapes

Almost any material can be milled, although difficulties arise with very brittle materials (e.g. ceramics) and very hard materials (e.g. tool steel). Milling is used in metals primarily to shape parts by cutting edges, slots or grooves. It is often used to complete parts that have been formed by a near-net-shape process (e.g. casting or forging). Milling is unusual for wooden products, although variants such as routing can be used to form grooves and mouldings.

Economics

Milling machines vary in price from £1,000 to £1,000,000. Milling is generally a very slow way to produce a component - but it can be economic for prototyping or small batches. High speed machining centres are used where the accuracy of milling is required to finish a component. The cost of milling on a commercial scale is often a balance between higher speed and longer tool-life.

Typical products

Finishing surfaces (e.g. top of engine block), wooden furniture, architectural mouldings