Swiss-Type Lathe setup, maintenance and daily checks
Swiss-Type Lathe is a sliding headstock lathe where the bar is supported close to the cutting point by a guide bushing. It is used for long, slender turned parts where the length to diameter ratio defeats a conventional lathe. This entry explains what it is, what the numbers on a data sheet mean, and what to put on a drawing.
It is written from the point of view of the buyer and the drawing office: the values that are realistic in production, the ones that cost money, and the way the result is verified. Where an industry sets the requirement, medical is used as the example: validation evidence that matches the drawing exactly.
Setup
- Establish the datum on the part or the fixture and indicate it, rather than assuming it.
- Set the tools and record the offsets; a tool length set by eye is the commonest source of a scrapped first part.
- Run a first part, measure it, and adjust from the measurement.
Daily checks
- Coolant concentration and flow, because a dry cut changes both the tool life and the size.
- Chip clearance in the fixture, because a chip under the part moves it.
- Verification: optical comparator and laser micrometer for small diameters, repeated at the start of a run and after any adjustment.
Wear and consumables
Tools, filters and coolant are consumables, not overheads. Bar size and cycle time, because material dominates, and the cost of replacing them early is far below the cost of a scrap part.
| Specification | Typical value |
|---|---|
| Bar capacity | up to 32 mm |
| Turning length | up to 300 mm per pass |
| Spindle speed | 8,000 to 12,000 rpm |
| Live tooling | yes, cross and end working |
| Positioning accuracy | ±0.003 mm |
| Back working | sub spindle with C axis |
Applications
Swiss-Type Lathe is used for long, slender turned parts where the length to diameter ratio defeats a conventional lathe, and in practice it appears most often in bone screws, connector pins, watch and instrument parts, fuel injector components.
How it fits into a machining route
Swiss-Type Lathe is one station in a route rather than the whole of it. The part arrives with the previous operation finished and leaves with the features it is responsible for completed, so the datum and the clamping method are agreed before the first part rather than discovered on it.The route is fixed before the first part is cut, and it is the route rather than the individual setting that holds the result: bar size and cycle time, because material dominates. Where a drawing calls for something the route cannot hold economically, that is raised at quotation rather than after the parts are made.
Standards, documentation and what is issued
The documentation requirement is ISO 13485 for medical work. Material is supplied against a certificate where the application calls for it, inspection results are recorded with the job, and the records are kept so that a repeat order can be compared with the first instead of being measured from scratch.
Optical comparator and laser micrometer for small diameters is the verification step. Where a customer format or a standard report is required, it is agreed before the batch starts, because a report written after the event is a report nobody can use.
Frequently asked questions
What tolerance should be specified for Swiss-Type Lathe?
±0.005 mm is realistic in production. Tightening it beyond the functional requirement increases cost without improving the part.
Which material is usually used?
316L stainless steel is the usual choice, supplied against ISO 13485 for medical work.
How is the result verified?
Optical comparator and laser micrometer for small diameters, with the results recorded so a repeat order can be compared with the first.
What is the most common mistake?
Assuming the same tolerances as a grinding operation on long slender diameters.
How long does it take and what does it cost?
A realistic cycle is 1 to 5 minutes per part in volume, and the cost driver is bar size and cycle time, because material dominates.
Related capability
If you are specifying Swiss-Type Lathe on a drawing and want a second opinion on the route, send the model and the quantity. The first response is a manufacturability review with the likely risk points and a quotation, so the decision can be made on facts rather than on a price alone.
Machining, inspection and documentation are handled in one place, which is why the dimensional report and the material certificate arrive with the parts rather than after them.
Related entries
These entries sit next to Swiss-Type Lathe in the encyclopedia: Sinker EDM Machine, Surface Grinding Machine, Sinker EDM. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.
