Greek CNC Factory: Precision Engineering

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  Key takeaways
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  Greek CNC factory selection criteria
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  What tolerance actually means on a quote
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  When five-axis is worth it and when it is not
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  Certifications, inspection, and what to verify
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  Lead time, MOQ, and how quotes are built
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  How to vet a Greek CNC factory in six steps

Every shop prints a tolerance number. Few explain what it costs. A ±0.005 mm callout on a 20 mm aluminum bracket is routine for a well-kept 3-axis mill. The same callout across a 400 mm steel housing with six bores on four faces is a different job, and it should be priced differently. When you evaluate a Greek CNC factory, ask which machine will cut which feature. If the answer is a single machine for all features, you are probably looking at a shop that will refixture and hope.

The position tolerance matters more than the size tolerance on most assemblies. A bore that is 0.01 mm oversize may still mate fine; a bore that is 0.05 mm off its datum will not. Ask how datums are established, whether the fixture locates on a machined surface or a raw casting, and how the shop verifies position after the part comes off the table. CMM reports on request are a reasonable ask, not an insult.

Surface finish runs alongside tolerance and often gets ignored until the parts arrive. As-machined finishes land around Ra 1.6–3.2 μm. A high-quality finish runs Ra 0.8–1.6 μm. Fine finishes reach Ra 0.2–0.8 μm, and those usually need a separate finishing pass or a different tool path. If your drawing shows a fine finish on one sealing face only, say so. Shops that apply the tightest finish everywhere will charge you for it everywhere.

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  Tolerance is feature-specificIt depends on size, material, and how many setups the feature needs.
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  Position beats sizeDatum strategy drives assembly fit more than a few microns of bore diameter.
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  Finish has three bandsRa 1.6–3.2 μm, Ra 0.8–1.6 μm, and Ra 0.2–0.8 μm; price them separately.

Five-axis machining adds two rotary axes so the tool can reach the workpiece from angles a 3-axis machine cannot. The practical benefit is not exotic geometry. It is fewer setups. A part that would need four fixtures on a 3-axis mill can often be finished in one or two on a simultaneous 5-axis center. Every removed setup removes a stack of positional error and a queue slot on the shop floor.

The trade-off is programming time and rigidity. Five-axis tool paths take longer to prove out, and the rotary axes can be less stiff than a solid 3-axis table. For a simple plate with holes on one face, five-axis is slower and more expensive. For a housing with features on five sides, angled ports, or a contoured pocket, it usually wins on total cost. A shop with 16 simultaneous 5-axis centers and 27 three-axis machines can pick the cheaper route for you. A shop with only one type cannot.

Part size matters too. Five-axis work envelopes vary widely. Compact machines cover 500 × 500 × 450 mm or 500 × 310 × 200 mm. Medium machines reach 750 × 1,150 × 550 mm and 600 × 600 × 600 mm. Large travel goes to 4,000 × 400 × 150 mm. If your part is 1,200 mm long and you are talking to a shop whose largest 5-axis envelope is 600 mm, the conversation is over before the quote.

Material changes the decision. Aluminum 6061 and 7075 cut freely and hold tight tolerances with good tooling. Titanium TC4 (Ti-6Al-4V) and Inconel move under heat and wear tools fast, so the shop needs the right coolant strategy and slower feeds. Magnesium AZ31B and AZ91D cut quickly but require chip handling discipline. Ask what the shop has actually run, not what it lists.

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  Choose five-axis whenFeatures on three or more faces, angled holes, contoured pockets, tight position across datums.
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  Stay with three-axis whenSimple plates, one-face work, loose position, high volume where cycle time dominates.
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  Check the envelope firstA 600 mm machine cannot cut a 1,200 mm part no matter how good the programmer is.

Certificates are a starting filter, not a verdict. ISO 9001:2015 covers quality management basics. IATF 16949:2016 adds automotive-specific traceability and change control. ISO 13485:2016 applies to medical device manufacturing and brings stricter process validation. ISO 27001:2022 covers information security, which matters if your drawings are the product. Ask for the scope statement on each certificate. A certificate that names a different legal entity or a different site is not the certificate you need.

Inspection is where claims get tested. A shop running 100% inspection before shipment will catch a bad bore before it reaches your dock. Ask what is checked, with what instrument, and what the record looks like. Raw material check, in-process monitoring, and final inspection are three separate gates. Reports on request are standard. A shop that cannot produce a dimensional report for a ±0.005 mm feature is telling you something about its process control.

Qualification rate is a useful number, but only if the shop defines it. A 99.99% figure usually means the share of parts that pass final inspection on the first pass. Ask whether reworked parts count. Ask how scrap is handled on a 10,000-part run. These questions separate a shop that measures from a shop that markets.

Confidentiality deserves the same treatment. Secure uploads and an NDA on request are reasonable expectations for any precision job. If your part is a pre-release product, the NDA should be signed before the first drawing moves, not after the quote.

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  Match certificate to siteName, address, and scope must line up with the factory doing the work.
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  Three inspection gatesIncoming material, in-process, final. Ask which one produces the report you receive.
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  Define the quality numberFirst-pass yield and rework treatment are different metrics.

Lead time is quoted in stages, and you should ask about each one. Quotation and DFM analysis within 12 hours is the first stage. Production start within 24 hours is the second. Parts ship in 3–5 days is the third. A supplier that quotes a single delivery date without breaking out these stages is hiding the part that usually slips. Historical late-delivery probability below 2% is a meaningful benchmark if the shop tracks it.

MOQ is a signal about the business model. No minimum order quantity means the shop is set up to run one prototype and a 10,000+ part run on the same process. That matters for two reasons. First, you can validate the design before committing to volume. Second, the process you qualify on the prototype is the process that runs in production, so you are not re-qualifying later. A shop that demands tooling before the first part is usually a different kind of supplier.

Quote structure tells you where the risk sits. A good quote separates material, machining time, finishing, and inspection. It notes any feature that is hard to hold and suggests an alternative. It flags a tolerance that will add cost. If a quote is one line and a number, expect change orders later. The DFM feedback is often worth more than the price difference between two shops.

Finishing adds lead time and should be quoted as a line item. Anodizing, plating, powder coating, bead blasting, and laser marking each run on their own schedule. Laser marking has a minimum character height of 1.5 mm, so fine text on a small part may need a different approach. Plan finishing into the schedule rather than discovering it after machining.

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  Break out the scheduleQuote stage, production start, and shipping are three different promises.
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  No MOQ means process continuityThe prototype and the production run follow the same routing.
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  Price finishing separatelyIt has its own queue and its own constraints.