Swiss-type turning

In Swiss-type turning, material is fed through a guide bushing positioned close to the cutting edge, which sets the process markedly apart from conventional turning. The short, supported distance between guide bushing and tool minimises deflection of the part during machining, making it possible to hold tight tolerances even on parts with a high length-to-diameter ratio, where conventional turning often produces vibration and an unstable surface.

The increased stability also lets us work at higher cutting speeds on slender parts without compromising surface quality. That gives a shorter cycle time per part than would be possible on a conventional turning machine with equivalent geometry, and it is a major reason Swiss-type turning is often the economically correct process at high unit counts.

The precision of the guide bushing is maintained continuously, because even minor wear in the bushing can propagate into the part's tolerance over a long production run. We check the bushing's condition as a fixed part of our preventive maintenance, so the process remains stable throughout the machine's operating life, not just in the first months after setup.

With driven tools on the Swiss lathes, a part can go through several machining steps in a single setup: cross drilling, milled faces, countersinks and threading, all while the part is still held in the primary setup. That means the mutual tolerances between these features can be held very tight, because there is no re-clamping between steps.

Back working allows the reverse side of the part to be finished immediately after it is parted off from the bar, without manual handling between primary and back-side machining. That reduces both lead time and the risk of introducing errors in the transition between the two machining stages, and it means the part leaves the machine as a finished component.

The high degree of integration in the process places great demands on programming and tool planning, because several tools must be coordinated within a limited work envelope without colliding. We simulate these sequences thoroughly before releasing a new setup for production, significantly reducing the risk of errors when a new part type starts up for the first time.

Swiss-turned components are widely used in medical devices, where requirements for surface quality, cleanliness and geometric precision are high, and parts are often small and complex. Here the combination of tight tolerance and fine surface finish works alongside the other documentation and traceability requirements standard in the medical industry.

In instrumentation and precision mechanical assemblies, Swiss-turned parts are typically used as shaft components, bushings and fasteners, where function depends on several small geometries fitting together precisely. Here it is often the mutual tolerance between several features on the same part, rather than any single dimension in isolation, that is the real challenge.

Hydraulic components, where sealing and movement depend on a very fine surface finish, are another typical application area. Here we work closely with the customer to establish which surface roughness is actually needed, since an unnecessarily fine finish can add cost to the process without a corresponding functional benefit.

Swiss-turned parts are often small and geometrically complex, which places particular demands on measurement equipment. We use 3D measurement equipment capable of handling the fine detail and tight tolerances typical of Swiss-turned components, and the inspection plan is designed to cover critical dimensions without making the check unnecessarily time-consuming.

For parts with several critical features on the same component, we place emphasis on documenting the mutual relationship between dimensions, not only each dimension in isolation. It is often exactly that mutual relationship that determines whether the part functions correctly in the customer's assembly, and it is therefore a central part of the documentation delivered with the part.

Inspection reports are tailored to the customer's needs, and for customers requiring full traceability we can link a specific delivery to the material batch the parts are made from. That gives a documentation trail that can be traced back if questions about a specific delivery arise at a later date.