Swiss CNC Factory: 7 Essential Checks Before You Buy

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  Key takeaways
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  Swiss CNC factory checks at a glance
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  What a Swiss CNC factory actually is
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  Reading a tolerance claim without getting burned
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  Certifications, data handling and MOQ
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  Lead time, quote quality and the parts that do not fit
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  Matching material and finish to the application
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  How to screen a Swiss CNC factory in 7 steps

A Swiss CNC factory is not defined by the country in its name. The term comes from sliding-head lathes, machines that push bar stock through a guide bushing and cut close to the bushing. The workpiece moves, the tool stays near the support point. That geometry is why these machines hold tight diameter tolerance on long, slender parts.

The practical consequence is a size limit. Sliding-head work suits parts roughly under Ø32 mm with a length-to-diameter ratio above 3:1. Above that, a mill-turn center with a Ø400 mm rotary table does the same job with less risk of deflection. A supplier that lists only one of the two is telling you something about its part range.

GreatLight runs both sides. The shop floor has 127 high-precision CNC machines, including 16 simultaneous 5-axis machining centers, 16 mill-turn centers, 12 four-axis mills and 27 three-axis machines. Maximum processing size reaches 4,000 mm, so the same supplier can quote a Ø6 mm fitting and a 4,000 mm structural beam.

Ask one question on the first call: which machine will run my part, and why that one? A clear answer mentions bar diameter, part length, feature access and cycle time. A vague answer usually means the quote was priced without a process plan.

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  Sliding-head latheBar stock under Ø32 mm, long slender turned parts, tight concentricity.
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  Mill-turn centerLarger diameters, milling and turning in one setup, up to 4,000 mm length.
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  5-axis centerFreeform surfaces, undercuts, compound angles, fewer setups.

±0.005 mm is a real capability, and it is also the most misused number in machining quotes. The figure applies to a defined feature on a defined material under defined thermal conditions. It does not apply to a 300 mm aluminum plate that warms up during a 40-minute cycle.

Ask how the feature will be measured. A bore checked with a plug gauge, a bore checked on a CMM, and a bore checked with calipers are three different claims. For a 50-piece run, we normally propose in-process checks plus a final inspection report with the critical dimensions listed.

Surface finish follows the same logic. Ra 0.2–0.8 μm needs slower feed rates and often a finishing pass on a separate setup. Ra 0.8–1.6 μm is the usual production band. Ra 1.6–3.2 μm is as-machined and is fine for brackets and covers. Putting Ra 0.4 μm on a non-sealing face adds cost for no function.

When you compare two quotes, check whether the tolerance and finish callouts match your drawing exactly. A cheaper quote often means the shop quietly relaxed a datum or a finish note, and the part arrives functional but out of spec.

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  Name the critical featuresMark them on the drawing and ask for them in the inspection report.
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  Match finish to functionSealing and sliding faces need fine finish; cosmetic faces rarely do.
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  Confirm the gaugeCMM, plug gauge or micrometer, written into the quote.

Certificates matter, but only with scope. ISO 9001:2015 covers the quality management system. IATF 16949:2016 applies to automotive production parts. ISO 13485:2016 applies to medical devices. ISO 27001:2022 covers information security, which is what protects your drawings and CAD files.

Ask for the certificate number, the issuing body and the expiry date. Then ask which site the certificate covers. A group with several plants may hold a certificate at one address and run your part at another. For medical and automotive work, this gap causes audit findings later.

Information security matters more than most buyers expect. Uploads should be treated as secure and confidential, and an NDA should be available on request. If your part is a pre-release product, that clause belongs in the first email, not in the purchase order.

On order size, no minimum order quantity is the norm for prototype work. One piece is a valid order. The cost driver is setup and programming time, not material. A supplier that quotes one prototype and a 10,000+ part run from the same process plan is usually the one that can scale with you.

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  Certification scopeCertificate number, issuing body, expiry, and the address it covers.
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  NDA before drawingsAsk for it on the first contact if the design is not public.
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  No MOQOne prototype through 10,000+ part runs on the same process plan.

Lead time claims are only comparable when the clock has a defined start. Our quotation and free DFM analysis come back within 12 hours, production can start within 24 hours, and parts ship in 3–5 days. Those numbers assume the drawing revision is frozen and the material is a standard grade in stock.

Exotic material changes the schedule. Inconel and Ti-6Al-4V cut slowly, tool wear is high, and a small batch can take two to three times the cycle time of 6061 aluminum. That is a physics problem, not a service problem. A supplier that quotes Inconel at aluminum speed has not read the drawing.

Some parts should not go to a Swiss CNC factory at all. Thin-wall tubes under 0.5 mm wall thickness, parts needing mirror polish on internal bores, and single-piece castings with internal cooling channels are better served by other processes. A good supplier says so early and points you elsewhere.

The honest answer to a lead-time question includes the material, the finish, the inspection level and the revision number. Anything shorter than that is a sales number.

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  Freeze the revisionLead time starts at drawing release, not at first contact.
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  Standard grades ship faster6061, 304, 303 and 17-4PH are usually in stock.
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  Know the wrong fitVery thin walls, mirror internal bores, cast internal channels.

Aluminum covers most prototypes. 6061 and 6061-T6 machine cleanly, anodize well and hold ±0.005 mm on short features. 7075 is stronger but galls more and needs sharper tooling. 2024 has better fatigue behavior and worse corrosion resistance, so it usually gets a protective finish.

Stainless behaves differently at the machine. 303 is the free-machining grade and the safest choice for turned parts. 304 and 316L work harden, so light cuts and constant feed matter. 17-4PH (SUS630) gives high strength after aging and is common in aerospace and medical brackets.

Titanium and nickel alloys are where process planning shows. TC4 (Ti-6Al-4V) needs low cutting speed, high coolant pressure and rigid setups. Inconel is worse on tool life. Magnesium AZ31B and AZ91D machine fast but require chip control and fire-safe handling.

Finishes follow the function. Anodizing for wear and color, hardcoat for sliding surfaces, electroless nickel for uniform coverage on complex geometry, bead blasting for a matte cosmetic face. Laser marking works down to 1.5 mm character height, which is the limit for readable part numbers.

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  AnodizingClear, color, hardcoat and conductive variants for aluminum parts.
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  PlatingElectroless nickel, zinc, silver and gold for conductivity and wear.
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  CosmeticBead blasting, tumbling, brushing and polishing.