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THE AUTOMATIC LATHE

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1. The cam automatic lathe

2. History

These are machines that appeared at the dawn of the 20^th century, also called “automatic lathes”. The Automatic lathe is the machine that symbolises the horological industrial revolution and the need to mass-produce small, high-precision parts while guaranteeing the Interchangeability of components. The purpose and value of the Automatic lathe lie in its ability to mass-produce small-sized parts with great precision.

3. Operating principles

The Automatic lathe is a machine for machining parts of revolution (turning of cylindrical parts). The material is worked from rotating bars, cut by a Graver (usually several Gravers), whose movements are automated, as are the rotation speeds of the material bar and its feed.

The automation of the first automatic lathes was mechanical. Various synchronised cams controlled levers that operated all of the machine’s movements. This type of machine developed until the 1980s. Computing and numerical controls have since replaced the cams. The machines have become more precise, more productive, more autonomous and more versatile. Renowned for their reliability, precision and longevity, the “old” cam machines are still present and used in many workshops.

Figure 1

CNC automatic lathe

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4. Materials, dimensions and precision

Nowadays, automatic lathes are capable of machining all materials suitable for machining (steels, brass, titanium, aluminium, gold, platinum, plastics, composites, etc.).

Components produced by profile turning in watchmaking have an overall diameter ranging from a few tenths of a millimetre to about 20 mm, and can machine pivots of 0.08 mm with a precision on the order of a micrometre (micron).

5. Components produced by profile turning

Among the watchmaking components typically produced by profile turning are: screws, pins, arbors, pinions, barrels, etc.