Precision CNC Swiss Processing Service
This guide is for engineers and buyers sourcing long, slender, tight-tolerance parts. It covers when Swiss-type turning beats conventional turning, which shops can actually hold ±0.005 mm, and the checks to run before you send a PO.
In this article
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
Key takeaways
Swiss-type turning against conventional turning
Use this to decide which process the RFQ should go to.
| Criterion | Swiss-type turning | Conventional turning |
|---|---|---|
| Part length to diameter | Above 5:1 without a steady rest | Below 3:1 in most cases |
| Typical diameter range | Ø0.5 mm to Ø32 mm bar | Ø5 mm to Ø4,000 mm |
| Bushing support | Guide bushing at the cut | Chuck only, part overhangs |
| Cycle time on small parts | Fast, bar fed continuously | Slower, one part per load |
| Secondary operations | Live tools and pickoff in cycle | Often a second setup |
| Best fit | Long shafts, pins, bone screws | Large housings, plates, flanges |
| Cost driver | Bar stock and cycle time | Setup and fixturing |
When to choose Swiss-type turning
Choose a precision CNC Swiss processing service when the part is long, slender, round and needs features on both ends. Choose a mill or mill-turn center when the part is short, prismatic or larger than the bar capacity.
Why a guide bushing changes the tolerance you can hold
On a Swiss-type machine the bar stock slides through a guide bushing and the cutting tools move to the work, not the other way around. The bushing sits within microns of the tool edge, so the material is supported almost at the point of cut. Cutting force has nowhere to push the part. That is the whole reason a precision CNC Swiss processing service can hold ±0.005 mm on a part that would deflect on a chuck lathe.
The practical effect is on overhang. On a conventional lathe, a Ø3 mm shaft sticking 60 mm out of the chuck will bend under tool pressure and chatter. On a Swiss machine the same shaft is supported at the bushing, and only the few millimeters ahead of the tool are unsupported. Length-to-diameter ratios of 10:1 and beyond become routine rather than a special setup.
The trade-off is diameter. Swiss machines are bar-fed, so the part must start from round stock that fits the bushing. For our work that means Ø0.5 mm up to roughly Ø32 mm depending on the machine. If your part is a 300 mm housing or a plate with pockets, this is the wrong process and a 3-axis or 5-axis mill is the right one.
Swiss work also tends to arrive complete. Live tooling drills cross holes, mills flats and slots while the part is still on the bar, and a sub-spindle picks the part off to machine the back side. Fewer re-fixtures means fewer datums to stack up, and less chance of a concentricity error creeping in between operations.
Which parts belong on a Swiss machine
Start with the shape. If the part is longer than it is wide, rotates around a single axis, and carries features on both ends, it is a strong candidate. Medical bone screws, dental implant components, connector pins, sensor housings, fuel injector parts and small valve spools all fit this description. The common thread is that the part would sag or vibrate if you held one end in a chuck.
Then look at the feature count. A part that needs a drilled cross hole, a milled flat and a chamfer on the back end is where Swiss economics pay off. Doing those on a mill after turning means three setups and three chances to lose concentricity. Doing them in cycle means one setup and one datum.
Some parts look like Swiss work but are not. A short, fat bushing with a large bore is cheaper on a conventional lathe or a mill-turn center because bar feeding gives no advantage. Thin-wall tubes that would collapse in a guide bushing need a different support strategy. Very hard materials above 60 HRC are usually ground, not turned, at least on the finishing pass.
Volume matters less than people assume. Swiss machines are not only for 10,000-piece runs. Bar feeders make small batches efficient too, and setup on a well-tooled machine is measured in hours, not days. We run everything from one prototype to 10,000+ part runs with no minimum order quantity, so a 20-piece build is a normal job.
How to judge a supplier's real capability
Ask what tolerance they will commit to in writing, on your drawing, not in a brochure. A shop that quotes ±0.005 mm on every feature has not read the part. Some features on a Swiss part are easy to hold and some are not, and the honest answer separates them. Bore depth, thread pitch diameter and true position on a cross hole are the usual trouble spots.
Ask how they measure it. A micrometer on the shop floor proves a diameter but not a position. A CMM with a stated uncertainty proves both. For medical and aerospace work, ask for first article inspection reports and material certificates by heat lot. We run 100% inspection before shipment with raw material checks, in-process monitoring and a final inspection, and we provide reports on request.
Ask about certifications that match your industry. ISO 9001:2015 covers general quality systems. IATF 16949:2016 matters for automotive and EV programs. ISO 13485:2016 is the one that matters for medical devices. ISO 27001:2022 covers information security, which is relevant if your drawings are sensitive. A supplier with all four has been audited on more than one axis.
Ask about material experience in your specific alloy. Anyone can turn 6061 aluminium. Ti-6Al-4V, Inconel 718 and 17-4PH stainless behave differently: they work-harden, they hold heat at the edge, and they tear if the feed and coating are wrong. Ask what tool coating and coolant strategy they use on your alloy, and listen for a specific answer.
Quoting, lead time and what a good RFQ contains
A useful quote comes back with more than a number. It should tell you the process route, the tolerance per critical feature, the material spec, the finish, the inspection plan and the lead time. If any of those are missing, the price is not comparable to another supplier's price. We return a quotation and a free DFM analysis within 12 hours, and production can start within 24 hours of approval.
Lead time on Swiss work is short because the setup is short. Our parts typically ship in 3–5 days once material is on hand. What stretches a schedule is usually not machining, it is a missing dimension, an ambiguous thread callout or an unspecified finish. Fix those before you send the RFQ and the timeline holds.
The RFQ should carry a 2D drawing with tolerances, a 3D model, the material grade with condition, the surface finish callout, the quantity per revision and any inspection or documentation requirements. For medical parts, say so up front. It changes the routing, the traceability and the paperwork, and it is cheaper to plan for it than to add it later.
Confidentiality is a normal request, not an awkward one. Uploads are handled as secure and confidential, and an NDA is available on request. If your program is under a customer NDA, tell the supplier before you share files so the paperwork is in place first.
Five mistakes that cost time and money
The first is quoting a Swiss job to a shop that will run it on a chuck lathe without telling you. The price looks better and the parts arrive with taper or chatter. Ask directly which machine the job will run on, and ask what the length-to-diameter ratio is on the longest feature.
The second is an ambiguous thread callout. A drawing that says M3 without a pitch, class or whether it is a rolled or cut thread will come back as a question or, worse, as the wrong part. Specify the standard, the class and the inspection method.
The third is a surface finish that nobody costed. Ra 0.2–0.8 μm on a turned diameter is achievable but it changes the tool, the feed and sometimes the cycle time. If the finish is decorative on one face and functional on another, say which is which.
The fourth is treating certification as a formality. If your end customer requires ISO 13485 or IATF 16949, the supplier has to hold it before the job starts, not after. The fifth is skipping the NDA until files are already shared. Put the agreement in place first, then upload.
Step by step: from RFQ to first article
What a well-run Swiss job looks like from the buyer's side.
- 1Send the full data package2D drawing with tolerances, 3D model, material grade and condition, finish callout, quantity. Missing data is the most common cause of a slow quote.
- 2Read the DFM notes before the priceLook for flagged features: deep small bores, thin walls under 0.5 mm, tight true position on cross holes, or a surface finish that forces a second operation.
- 3Confirm the bar size and process routeCheck that the largest diameter on the part fits the supplier's bar capacity. On Swiss work the bar diameter is a hard boundary, not a preference.
- 4Agree the inspection planName the critical dimensions, the gauge or CMM to be used, and the reports you need. For medical or aerospace, request first article and material certs by heat lot.
- 5Approve the first articleCompare the FAI report against the drawing feature by feature. Do not approve on a visual check alone, especially on threads and position tolerances.
- 6Lock the revision and release the runAny drawing change after first article restarts the setup. Freeze the revision, then release the production quantity.
Questions buyers ask before a Swiss job
What is the smallest diameter you can machine on a Swiss machine?
Bar work starts around Ø0.5 mm. Below that the material handling and the tool edge become the limiting factors more than the machine itself.
For very small diameters, tell us the length and the feature detail in the first message. That lets us say early whether the part is practical.
Can you hold ±0.005 mm on every feature?
No shop can promise that on every feature of every part, and you should be cautious with one that does. ±0.005 mm is achievable on turned diameters and many milled features under good conditions.
Position tolerance on a deep cross hole or a long bore is a different problem. We review the drawing feature by feature and tell you which ones are routine and which need extra care.
Which materials do you run on Swiss machines?
Aluminium grades including 6061, 7075 and 2024; stainless including 303, 304, 316L, 17-4PH and 440C; steel including 1045, 4140 and 4340; copper and brass including C36000 and beryllium copper.
Titanium TA1, TA2 and TC4 (Ti-6Al-4V), Inconel and magnesium AZ31B also run, but they need specific tool coatings and cooling. Expect a longer DFM discussion on those.
Do you have a minimum order quantity?
No minimum order quantity. We run from one prototype to 10,000+ part runs.
Small batches are normal on bar-fed machines, so a 20-piece build does not carry a penalty the way it does on a large mill.
What certifications do you hold?
ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022.
If your program needs specific documentation, name it in the RFQ so it is built into the routing and the inspection plan.
How fast can I get parts?
Quotation and free DFM analysis within 12 hours, production can start within 24 hours, and parts typically ship in 3–5 days.
Historical late-delivery probability is below 2%. The usual cause of a slip is an incomplete data package, not machine time.
Send the drawing, get a process answer
Upload your 2D drawing and 3D model. We return a quotation and a free DFM analysis within 12 hours, with the tolerance and process route stated per feature.
12-hour quote100% inspectionNDA on request
More from GreatLight
We publish setup notes, tooling trials and inspection data from the factory floor.
