CNC Swiss-type automatic lathes are more powerful than ever - while retaining the fast-cycle times with the same flexibility that makes them a standard for most precision, high-production applications.
Today even more tools and greater options are available. Sophisticated controls usher streamlining into the machining process. Swiss screw machining is always preferred for the longer, more slender turned parts, widely used for smaller, highly complex parts and works well for the pieces that have no turned surfaces at all.
Conventional lathes have a fixed headstock. The workpiece itself is held in a chuck or collet. It extends into the machine enclosure working as a cantilever. It can also be supported on the end - by the tail-stock.
To distinguish a Swiss machine from others in its class - observe it's headstock move. A bar-stock passes through a chucking collet in the headstock - which clamps onto it.
Why Swiss Screw Machining So Valuable?
Swiss screw machining means that the bar emerges into the tooling area through a guide-bushing which locates the bar radially during machining.
The headstock then moves very precisely back-and-forth in the z-direction - taking the bar with it. The turning-tools carried on gang-slides contact the bar very close to the guide bushing.
The bar motion provides feed for this cutting action. Gang-slides carry holders for fixed single-point or other tools and may support live-tooling. Many machines have a secondary spindle back, working tool stations and sometimes one or more turrets that carry more tools as well.
The purpose of supporting the workpiece with the guide bushing is to maintain precision throughout the machine workpiece.
Any physical object subjected to a force - will deflect. On conventional lathes, if the cutting forces cause too great a deflection - the accuracy of the cut suffers. If you hold a workpiece securely at one end - then push sideways on the unsupported end - the workpiece bends a certain amount. Push with the same force on a longer workpiece - it will bend more.
With Swiss screw machining - the guide bushing supports the workpiece so close to the tools - that the deflection due to the cutting force is essentially zero. The result means you can take heavy cuts and still maintain precise dimensions on the part.
Swiss turning is used to make small, slender, complex and precision components. This is possible due to unique design. In the Swiss turning machine - the bar-stock material is gripped tightly and advanced by the sliding headstock through a guide bushing to the machining section.