Swiss-Type Turning for Micro Parts: When a Sliding-Head Lathe Is the Right Call

By the Micropartz editorial team · Published October 25, 2026

A Swiss-type lathe is the standard machine for small, slender turned parts. If your part is round, longer than it is wide and needs diameters held to a few microns, it is very likely to be made on one. This guide explains how the machine works, which parts suit it, what tolerances to expect and when another process is the better choice. For the wider picture of processes and tolerances, start with the micro machining buyer’s guide.

How a sliding-head lathe works

On a conventional CNC lathe, the bar is clamped in a chuck and the cutting tool travels along it. The further the tool gets from the chuck, the more the part deflects under cutting force. A 1 mm pin that sticks out 10 mm behaves like a fishing rod.

A Swiss-type lathe turns this around. The headstock grips the bar and slides it forward and back through a guide bushing, a precision sleeve fixed in front of the tools. The tools stay in place close to the bushing. At every moment the cut happens only a millimetre or two from the support, so the part hardly deflects no matter how long it becomes.

The design came from the Swiss watch industry in the late 19th century, where tiny screws and pinions had to be made by the thousand. Modern CNC Swiss-type machines add:

• Live tools for cross drilling, milling flats, slots and polygons while the part is still in the bar.
• A sub-spindle that takes the part at cut-off and machines the back face.
• Multiple tool gangs so turning, drilling and milling overlap in time.
• High-pressure coolant to break and flush chips from small bores.

The result is a finished part falling out of the machine every few seconds to a few minutes, often with no second operation.

Parts that suit Swiss-type turning

The best indicator is the ratio of length to diameter. Once it passes about 3:1, a conventional lathe starts to fight deflection and a Swiss-type machine becomes the natural choice.

Part family	Typical size	Why Swiss-type
Connector contacts and pins	⌀0.5 to 3 mm, 5 to 20 mm long	Long and slender, huge volumes
Bone and dental screws	⌀1 to 5 mm	Thread whirling on the machine, tight diameters
Watch pinions and staffs	⌀0.3 to 2 mm	Tiny diameters, fine finish
Cannulas and needle hubs	⌀0.8 to 4 mm	Long bores, thin walls
Sensor housings	⌀3 to 12 mm	Turned outside, milled features, one cycle
Valve spools and small shafts	⌀2 to 10 mm	Several diameters with tight runout

Size ranges are typical, not machine limits.

Parts that do not suit a Swiss-type lathe: prismatic housings, parts with large pockets on flat faces, anything that does not start from round or hex bar and parts that are shorter than they are wide. Those go to a micro mill or a conventional lathe.

Typical tolerances on Swiss-type work

Because the cut happens next to the support, Swiss-type machines hold diameters and concentricity very well. Typical production values in micro machining shops:

Characteristic	Typical capability
Diameter	±0.005 mm on selected diameters, ±0.01 mm general
Shaft fit	h5 to h6
Runout between diameters, one cycle	0.005 to 0.01 mm
Length	±0.01 to ±0.02 mm
Thread	6g / 6H standard, micro threads from M0.6
Surface roughness	Ra 0.4 to 1.6 μm

Values are typical, not a guarantee.

For a 4 mm shaft, h5 means the diameter may be between 4.000 and 3.995 mm, a band of 5 μm under ISO 286. That is routine on a well-run Swiss-type machine. The limit is often not the machine but thermal stability over a shift and the measurement method. Ask the shop how it measures critical diameters and how often.

Bar stock: the part nobody puts on the drawing

The guide bushing only works if the bar fits it closely. That has three consequences buyers should know.

Ground bar is usually required. Standard drawn bar may vary by several hundredths of a millimetre, which makes the bar chatter in the bushing. Shops order centerless ground bar, typically to h6 or h7, which costs more per kilogram. For most micro parts the extra cost is small per piece, but it affects lead time if the grade is unusual.

Remnant waste. The last part of each bar, often 100 to 300 mm, is held by the collet and cannot be used. On a small part that remnant can weigh more than the parts made from the bar. For expensive materials such as titanium or precious alloys, it shows up in the price.

Guide-bushing-less mode. Many modern machines can run without a guide bushing for short parts. This allows cheaper drawn bar and less remnant, at the cost of some of the slender-part advantage. If your part is short, ask whether the shop would run it that way.

Setup time versus cycle time

Swiss-type turning has a very different cost shape from milling.

• Setup means loading and adjusting up to 20 or more tools, programming overlapping operations and proving out the first parts. Several hours to a full day is normal.
• Cycle time is short. Small pins can come off every 20 to 60 seconds. Complex parts with milling take a few minutes.

Hypothetical example: a sensor pin needs 3 hours of setup and a 90 second cycle. At 20 pieces, setup accounts for about 85 percent of machine time. At 5,000 pieces, it is under 3 percent. The same part can therefore look expensive as a prototype and very cheap in production. If you want a fair comparison, ask shops to quote two or three quantities and state your yearly volume.

For prototypes, some shops will make the first 10 to 50 pieces on a CNC lathe with a mill, or on a micro mill, and move to Swiss-type for production. That is fine as long as the critical features are measured the same way on both.

Secondary operations on Swiss-turned parts

Many Swiss-turned micro parts leave the machine finished, but some still need work after cutting. Knowing which ones helps you judge lead times and compare quotes.

• Deburring. Cross holes are the classic problem. The exit of a ⌀0.3 mm cross hole into a ⌀1 mm bore is almost impossible to reach with a tool. Shops use electrochemical deburring, abrasive flow or thermal deburring for these, or plan the drilling sequence to minimize the burr.
• Cleaning. Swiss-type machines run with cutting oil. Parts are washed, often ultrasonically, before inspection and packing. Medical parts may need a validated cleaning process.
• Heat treatment. Hardenable stainless and tool steels are hardened after turning. Long slender parts can bend during heat treatment, so straightness may need to be checked or corrected afterwards.
• Surface treatment. Passivation of stainless, plating of brass contacts with nickel or gold and anodizing of aluminum are common. Plating thickness adds to diameters, so tight diameters must allow for it.
• Grinding or lapping. For diameters tighter than about ±0.002 mm or finishes below Ra 0.2 μm, a centerless grinding or lapping step may follow turning.

Secondary step	Typical reason	Effect on lead time
Electrochemical or thermal deburring	Cross holes, internal edges	Adds days if subcontracted
Ultrasonic cleaning	Oil and chip removal	Minor, usually in house
Heat treatment	Hardness on 420, 440C, tool steels	Adds days, may need straightening
Plating or passivation	Conductivity, corrosion	Adds days to a week if subcontracted
Centerless grinding	Diameters beyond turning capability	Adds a process step

Typical values for orientation.

When a CNC lathe or micro mill is the better choice

Swiss-type is not always the answer. Consider alternatives when:

• The part is short and stubby. A length to diameter ratio under about 2:1 runs well on a precision CNC lathe with a sub-spindle, often with cheaper bar.
• The quantity is very low and will stay low. Ten parts a year do not justify a full Swiss-type setup.
• Most features are milled. A small housing with one turned bore is a milling part. The tolerance and materials reference shows how the typical limits compare.
• The material is not available as bar. Some plastics and special alloys only come as plate or rod in sizes that do not suit a guide bushing.

What to put in a Swiss-type RFQ

To get comparable quotes from Swiss-type shops, include:

1. STEP model and PDF drawing, with critical diameters and runouts marked.
2. Material and grade, and whether ground bar is acceptable or a specific supplier is required.
3. Thread specification, including whether rolled, whirled or cut threads are acceptable.
4. Edge and burr requirements on cross holes, which are the hardest place to deburr on a turned part.
5. Quantities at two or three levels plus expected yearly volume.
6. Inspection method for the tightest diameter and whether a first article report is needed.

Micropartz is a matching service. We send your RFQ to up to 3 shops that run Swiss-type or sliding-head lathes suited to your part size and material, in the supplier region you pick, and reply within 24 business hours. Details on the processes are on the micro machining page. When your drawing is ready, send an RFQ.

Frequently asked questions

Reviewed against

• Wikipedia: Screw machine (includes Swiss-style automatic lathes)
• ISO 286-2:2010, Tables of standard tolerance classes and limit deviations for holes and shafts

Numbers in this guide are typical values for orientation. The drawing, the material certificate and the matched shop set the real ones.

Keep reading

• Micro Machining: A Buyer's Guide to Very Small Precision Parts
• Minimum Feature Sizes, Tools and Tolerances in Micro Milling and Turning
• What Micro Machined Parts Cost and Why Inspection Is Half of It