Swiss-Type Lathe
Tsugami B0205-III — what we run on it.
Sliding-headstock Swiss-type lathe with 1mm to 20mm bar capacity, 2,000 PSI HPC, and FMB bar feeder. Used for small-diameter precision turned parts where length-to-diameter ratio exceeds 4:1 and tolerances tighter than 0.0005″ matter. Standard finish: 16 µin Ra; 8 µin achievable with finishing inserts.
01 · Specs
The machine.
- Max bar diameter
- 20 mm (0.787″)
- Min bar diameter
- 1 mm (0.039″)
- Main spindle
- 10,000 RPM, 5.5 kW
- Sub-spindle
- 10,000 RPM, 2.2 kW (back-work)
- Live tooling
- 8 main + 4 back, 8,000 RPM
- Y-axis
- Yes, ±20 mm — enables off-center milling, slotting, hex flats
- High-pressure coolant
- 2,000 PSI through-tool
- Bar feeder
- FMB Turbo 5-20 (12 ft, magazine-loaded)
- Positioning accuracy
- 0.0001″ X/Z, 0.0002″ Y
02 · Sweet spot
What this machine is for.
Swiss-type machining shines where the bar needs continuous support (sliding headstock + guide bushing) to maintain chatter-free turning on long, slender features. Real applications:
- Medical bone screws & surgical pins — Ti-6Al-4V or 316L. Diameters 1.5–6mm, lengths 20–80mm, multi-lead threads, often with slot-drives or hex broaches. Volume runs of 5,000–50,000.
- Aerospace electrical pins & sockets — BeCu C172, brass C360. Tight 0.0002″ OD on contact features, small-feature broaching, 0.0001″ concentricity. AS9100 traceability.
- Optical lens-mount adjusters — fine-thread (M3 × 0.35) titanium thumbwheels, knurled or polished, with broached drive features. Hand-feel matters; surface finish <8 µin Ra typical.
- Defense fuze components — 17-4PH H1025, complex small-diameter spinning parts with ID/OD relationships under 0.0003″.
- Custom dental abutments & instrument shafts — Ti-6Al-4V ELI. 100% concentricity inspection, single-piece traceability, lot serialization.
03 · Why Swiss
The bushing is the difference.
On a conventional lathe, the bar protrudes from the chuck and the cutting force tries to deflect it. As the L:D ratio grows past about 3:1, deflection causes chatter, taper, and dimensional drift. Swiss-type lathes solve this by sliding the bar through a guide bushing positioned within ~5mm of the cutting tool — the bar is supported right where it’s being cut.
Practical implications:
- L:D ratios up to 10:1+ are routine — features like a 3mm × 30mm shaft can hold 0.0002″ concentricity along its full length.
- Bar stock must be ground or precision-rolled — out-of-round bar will bind in the bushing or cause variation. We typically run h7 or h8 ground stock.
- Small features = fine cuts — depth-of-cut and feed are limited by tool stiffness on small-diameter inserts. Throughput is volume-limited, not metal-removal-limited.
- Sub-spindle handles back-work — part is parted off into the sub-spindle and machined complete from the back side, eliminating a secondary op for chamfer/threading on the cut-off end.
04 · Material strategy
What runs well, what doesn’t.
Swiss machines like clean-cutting materials with consistent chip control — the bushing is sensitive to chip pack-in. Our experience by alloy:
- 316L stainless
- Best-in-class for medical work. Predictable chip break, no bushing-galling. Run with cobalt-bonded carbide, AlTiN coating.
- Ti-6Al-4V
- Good. Lower SFM (200–300) and aggressive coolant required. Bushing wear is faster — replace every ~500 lb of stock through.
- Brass C360
- Excellent. The free-machining benchmark. 800+ SFM, dry chip clearing, near-zero bushing wear.
- BeCu C172
- Good with HSS or PCD. PCD is preferred — beryllium dust must be captured (HEPA filter on the machine).
- 17-4PH
- Workable in H1025 condition. Tougher than 316L; need longer-radius edges + lower feeds. H900 is too hard for guide-bushing work.
- Inconel 718
- Difficult. Bushing material has to match (carbide bushing for nickel work). Reserved for parts where Swiss is the only fixturing option.
- Plastics (PEEK, Delrin)
- Yes — but with slightly oversized bushing to prevent grabbing. Common for fluidic connectors and medical-disposable bodies.
05 · When NOT to pick this machine
Wrong-fit jobs.
Swiss-type is unbeatable in its sweet spot — high-volume, small-diameter precision — but several jobs run better elsewhere:
- Bar > 20mm → Tsugami B0326II (32mm capacity) or Doosan SMX 2600 (3.0″).
- Short, fat parts (L:D < 1.5) → Daewoo Lynx or Doosan SMX. Swiss adds setup/programming overhead with no benefit for chunky geometry.
- Low-volume prototypes (<25 parts) → Daewoo Lynx or Hardinge HC. Swiss programming and bar setup add 4–6 hours of NRE that doesn’t amortize on small lots.
- Heavy off-center milling features → Doosan SMX (B-axis tool spindle) or Mytrunnion 4G. Swiss live tooling is limited to ~8,000 RPM and has limited Y travel.
- Plate/slab work → vertical mill. No relationship to Swiss capability.
Inspection
100% in-process where it matters.
For volume Swiss work we run 100% in-process probing on critical OD and length features (Marposs in-machine probing), with statistical-process-control sampling on first/middle/last parts of every bar. CMM verification on lot-acceptance for AS9100 / ISO 13485 customers.
Runout and datum-referenced concentricity get verified on the Hexagon Global S CMM, while the Keyence IM-7000 image dimension measurement system handles fast, non-contact 2D diameter and length checks on sub-millimeter features the CMM probe can’t reach reliably.
Got a small-diameter precision part?
Send drawing + qty + material. We'll tell you whether Swiss-type is the right fit, or whether the Doosan SMX or another machine is a better path.
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