What is a Swiss Screw Machine?

Screw machines are automated lathes which can machine turned parts. The appellation "screw machine" might be slightly misleading, as they don't actually screw anything in, nor do they necessarily thread materials, although this is one of their functions. Essentially, a Swiss machine shapes components by holding a workpiece from the ends and middle while tools sculpt the workpiece from multiple sides. The machine's name comes from its origin: Swiss watchmakers created it to make tiny, precise screws. The Swiss machine's close cousin, the turret screw machine, functions differently but can achieve similar results. Turret machines are no longer manufactured, but they are still commonly used.

How Swiss Screw Machines Work?

A Swiss screw machine acts much like an altered lathe, in which it can spin a workpiece to sculpt it. However, there are some key differences. Firstly, a Swiss machine does not need to rotate the workpiece to carve it, although it can. Secondly, Swiss machining can move the workpiece along the Z axis, so its tooling doesn't move as in a lathe. Thirdly, these machines feature a bushing and collet that hold the workpiece, so that tooling always cuts into it millimeters from the edge of where it's held. Swiss machines are also capable of machining up to 13 axes and performing milling and threading operations.

These features enable several advantages for producing the intricate, high precision work for which Swiss machines are known.  Because the workpiece is shaped right next to the bushing, it can have a length and width ratio as extreme as 20:1. This added stability also avoids deflection (or bending) of the tool, enables higher accuracy, and allows the piece to be sculpted at multiple points simultaneously.

There are two main types of Swiss screw machines: automatic and CNC. We'll be covering both of these below, as well as details about turret screw machines, the CNC Swiss machine's close cousin.