Micro CNC machining concentrates the sourcing risk of any precision buy into a smaller envelope. The parts are tiny, their features are measured in tenths of a millimeter and microns, and their defects are proportionally easier to hide — a burr in a small internal feature, a residue in a fine hole, a drift that only a capable instrument can see. A buyer sourcing micro work is therefore not only verifying a shop's machines; they are verifying the shop's ability to measure what it machines.
That extra layer changes the verification sequence without complicating it. The entity, the certificates, and the process evidence are checked as with any supplier, and then a metrology layer is added: which instruments resolve the critical features, how they are calibrated, and whether the reports carry the method behind each reading. The pilot part closes the loop by proving the measurement story against an independent check. This guide walks the sequence, from desk to pilot.
What changes about verification when the parts are micro?
The first change is that the tolerance claim and the measurement capability must be read together. A shop that claims ±0.003 mm (milling) / ±0.002 mm (turning) on a micro feature is only credible if it holds an instrument that can resolve that band on the actual feature — a coordinate measuring machine or an optical system with the right resolution, calibrated and documented. On micro parts the instrument is part of the process, and a claim without an instrument behind it is a claim without a method.
The second change is that defects are harder to see and harder to rework. A burr inside a feature that is two millimeters deep cannot be inspected by eye; a residue in a small hole is invisible until the part is in service; and reworking a micro part that has drifted is often impossible, so the process has to be right the first time. The supplier's process evidence should show control of exactly these risks — the burr strategy, the cleaning, the edge condition — because on micro parts prevention is the only practical inspection.
The third change is administrative but real: micro lots are often small, frequent, and governed by the same documentation as full-size production. The verification burden per part rises, because each certificate and each report covers fewer parts. If you verify the supplier's documentation system once — through the desk checks and the pilot — you have paid that overhead a single time and collect it across every small lot that follows.
Which metrology questions should a micro buyer ask before paying?
Put the metrology questions next to the tolerance callouts on the first page of the file. For each critical micro feature, ask which instrument measures it, how that instrument is calibrated, and what the report will show for the smallest controlled dimension. The answers should name the CMM, the optical system, or the dedicated gauge, with the resolution and the calibration record behind each one. A feature that cannot be measured by the shop's own instruments cannot be verified by the shop's own report.
Ask how the measurement method was chosen for the drawing's features. A micro bore may be measured with an air gauge or a probe; a small thread may be verified with a functional gauge rather than a probe; a tight geometry may need an optical measurement system. The method decides whether the report's numbers are real, and you should see the method named on the report rather than implied. A report that shows values without a method is a report that cannot be audited.
Calibration closes the metrology question. The instruments behind the reports should carry current calibration records, and you should ask for them in the file. An instrument that drifts out of calibration invalidates every report it produced in the interval, and on micro parts, where the tolerances are near the instrument's resolution, calibration is not an administrative detail, it is the difference between a measured value and a guess.
What process evidence matters most for micro parts?
The process evidence a micro buyer should request is the same shape as any supplier's — redacted reports from real lots — but the content should answer micro-specific questions. Do the reports show measured values on small features, with the method named and the numbers inside the callouts? Do they cover the features that are hardest to measure, not just the convenient ones? And does the lot paperwork include the burr and edge-control evidence the drawing demands, because on a micro part a burr in the wrong place is a functional failure?
Read the evidence for signs of the supplier's actual control. A report whose values cluster exactly at the nominal with no spread may be measuring fewer parts than it claims; a report that names the instrument, the method, and the operator is a report produced by a real process. The evidence should also show the shop measures what it ships — the critical features on the final lot, not just the first article — because micro processes drift between setups and the drift is invisible without measurement.
The cleanliness story belongs in the same evidence set. Micro parts that leave the machine carry chips and residue that a full-size part might shed in handling, and a supplier that cleans, verifies, and packages to a stated expectation is a supplier that understands where micro defects hide. Ask how the shop cleans its micro parts, how it verifies the cleaning, and what the packaging protects against. The answers are part of the process evidence, and they are part of what arrives with the lot.
How is material control handled at micro lot sizes?
Material control on micro work is the same chain as any governed lot, with the small quantities making each link more valuable. The material certificate names the grade, the condition, and the heat or lot; the incoming check verifies the delivered stock against the certificate before cutting; and the heat number travels onto the work order so the finished parts trace to the material that was actually machined. A small lot does not justify a weaker chain — it makes the chain more important, because one bad lot is a larger fraction of the year's supply.
Ask the supplier how incoming stock is verified at its scale of purchasing. A shop that buys micro-quantity stock in certified lengths and checks each length against its certificate before cutting is running the chain; one that treats the certificate as a packing slip is not. The verification method matters as much on a micro part as on a full-size one, because an alloy substitution or a wrong condition passes every dimensional check and fails in service.
Name the material requirement precisely in the RFQ so the chain has a claim to verify. The grade with its condition and the certificate expectation belong on the drawing and in the order, and you should check at receiving that the certificate names the heat the work order records. On micro parts the materials are often the expensive ones — the titanium, the specialty stainless, the engineered polymers — and the cost of a wrong lot is not recovered by the small size of the part.
What should the pilot part prove at micro scale?
The pilot part on a micro order should prove the measurement story, not just the machining. Choose a non-sensitive micro part with a real critical feature — a small bore at a controlled tolerance, a fine thread, a tight geometry that the optical system must resolve — and require the full report package with it. Then measure the critical feature independently, with your own instrument or an independent reviewer, and compare the results with the supplier's values.
The comparison is the test. If the supplier's measurements match the independent check within the expected uncertainty, the measurement story is real and the production reports can be trusted. If they diverge, the shop either cannot measure the feature or did not measure the lot it shipped, and either finding is worth more than the cost of the pilot. On micro parts, where the features are near the resolution of the instruments, the agreement between two independent measurements is the only honest proof of the metrology.
The pilot should also produce the behavior evidence: the quoting questions, the report quality, the timing, and the handling of the inevitable small issues. A micro supplier that communicates precisely about small features, flags the measurement challenges early, and delivers a report that names its methods is a supplier whose production work can be managed at a distance. The pilot is the cheapest place to observe that behavior before the volume relationship begins.
How should payments be gated on a micro machining order?
The payment gates on a micro order carry the same logic as any cross-border buy, with the first-article evidence at the center. A deposit funds the material and the start, released after the entity checks and the structured quote are in the file. The next release follows the approved first article, measured independently and matched against the supplier's report. The final balance follows the pre-shipment check and the shipping documents, under the agreed incoterm. Each gate opens on evidence you can see.
Micro consignments are small and light, which shortens the freight leg — air is the natural mode and the crossing takes days rather than weeks. But the small size of the shipment does not reduce the value of the gates; it concentrates it. A micro part that fails in service stops an assembly just as completely as a full-size one, and the evidence chain that catches the failure before shipment is the same chain the gates enforce.
The gates should be written into the purchase order with their evidence named, so both sides know what opens each one. The supplier who accepts the gates on the pilot order will accept them on volume, because both rest on the same principle: money follows proof. The supplier who resists the gates at volume is asking the buyer to abandon the discipline that qualified them, and the answer to that request belongs in the red-flag column rather than in the payment schedule.
What should the RFQ carry so the quote and the delivery agree on micro work?
The micro RFQ should be written so the shop cannot answer it without engaging the metrology. Attach the drawing at a named revision with the critical micro features marked, name the material with its certificate requirement, and state the measurement method expected for each tight feature — the CMM, the optical system, or the dedicated gauge. State the finish and the cleanliness expectations, and list the report format the lot must ship with. A drawing that marks its critical features invites a quote that confirms how each will be made and measured.
Read the quote's confirmation for specificity. A supplier that answers "we will hold this bore at ±0.002 mm, measure it with the CMM on the datum frame, verify the thread with a functional gauge, and ship the report with the method named" is engineering the part inside its quality system. One that confirms the whole drawing with no questions has not read the features that matter. The specificity of the confirmation is the first test of whether the delivery will match the quote.
The RFQ should also ask the two questions that set expectations for micro work: which features are the most difficult to measure, and how will they be verified? A serious micro shop names the hard features before you find them, because it has measured similar parts before. The supplier that volunteers the measurement challenges is the supplier whose quote can be trusted, and the quote that hides them is the quote whose delivery will reveal them at the first article.
Which findings should end a micro sourcing process?
The standard findings end a micro sourcing process exactly as they end any sourcing process: an entity that shifts between documents, a bank account under a different name, certificate numbers that do not resolve, no process evidence, and payment pressure before any work exists. Each of these is visible in the file, and each is sufficient to stop. On micro work the stakes are the same as macro work; the parts are just smaller.
Micro adds its own findings to the list. A metrology story that does not add up is one of them: a claimed tolerance with no instrument in the shop that can resolve it, a report with values but no method, or calibration records that cannot be produced. A supplier that cannot name how it would measure the critical feature at the quoting stage has not measured that feature on any previous part. On micro parts the measurement story is the machining story, and a gap in the story is a gap in the process.
Micro sourcing stop list: no instrument that can resolve the critical features · reports without a named method · no calibration records · no burr and cleanliness evidence · the standard findings — entity shifts, unresolved certificates, no process evidence, payment pressure. Any single item pauses the process; two or more end it.
Micro CNC machining is bought on a double proof: the shop can machine the feature, and the shop can measure the feature. The verification sequence in this guide runs that double proof — the entity and certificates confirm who is being paid, the metrology questions confirm how the parts will be verified, the process evidence confirms what the shop has actually measured before, and the pilot part confirms the measurement story against an independent check. A supplier that clears the sequence is a supplier whose micro parts can be trusted at a distance, and the factory behind this site is used to being qualified exactly this way. Its factory page and quality page are written so the sequence's checks can be run against them.
What this shop actually runs
If you ask for capability evidence, you deserve a specific answer. This facility operates 100+ CNC machines across 6,800 m2 in Dongguan, China, staffed by 100+ people. The machines, listed by category:
- 5-axis machining centres (10+) - Mazak VARIAXIS I-600 (510/910/510 mm travel, 12,000 rpm, 22 kW, 71.6 N·m, 30-tool BT40) and Mazak INTEGREX I-250H S (B-axis 0.0001°, 24 kW, 124 N·m, 38-tool HSK-A63). Chosen for compound-angle parts, single-setup multi-face prismatic work, and aerospace fittings where datum transfer loss is unacceptable.
- 3-axis / 4-axis machining centres (50+) - Brother SPEEDIO S500Z2N / S700Z2N (10,000 rpm, 14/21-tool ATC, 0.7 s tool-to-tool, Z-axis 2.2 G) and Mazak VCE-430A L / VCE-570C L (10,000 rpm, 118 N·m, 24-tool ATC). Chosen for prismatic parts, plates, brackets, housings.
- Swiss-type turning centres (10+) - Citizen Cincom A20-3F7 (Φ20 mm, 10,000 rpm), TSUGAMI B0206-III / B0205-III (Φ20 mm, 0.1 µm), STAR SR-32JII / SR-32J Type N (Φ32 mm, 8,000 rpm). Chosen for long, slender rotational parts at ±0.002 mm.
- CNC turning centres (20+) - HEADMAN T70M/1250 (720 mm swing, 117 mm bore, 3,000 rpm, BMT75 12-station turret). Chosen for shafts, bushings, flanges up to ±0.002 mm.
- Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Chosen for hardened tool steel, internal splines, sharp internal corners that milling cannot reach.
- Inspection: Hexagon CMM + 20+ gauges - Hexagon CMM for coordinate measurement, plus vision system, profilometer, hardness tester, coating thickness gauge, XRF for material verification. The 10:1 rule (gauge 10x more accurate than the band) is applied to every feature.
- Machine highlights - VARIAXIS I-600: one-setup multi-face 5-axis + MAZA-CHECK auto-calibration; INTEGREX I-250H S: DONE-IN-ONE mill-turn, B-axis 0.0001° + Ai thermal shield; SPEEDIO S500Z2N / S700Z2N: Z-axis 2.2 G + 0.7 s ATC; Swiss-type: guide-bush switchable + 0.1 µm resolution.
Tolerance bands: ±0.003 mm milled, ±0.002 mm turned, ±0.002 mm ground or wire-cut. Capability indices: Ppk >= 1.67 at the initial study; Cpk >= 1.33 ongoing in production.
Certifications: ISO 9001:2015 (116024/A/0001/UK/En) · IATF 16949:2016 (131941/A/0001/SM/En, design clause 8.3 excluded) · ISO 14001:2015 (116024/B/0001/UK/En), held by Dongguan Zhuohang Ltd (USCC 91441900MA4UWT6X39, since 2005).
Service area: we supply Austria, Belgium, the Czech Republic, Denmark, France, Germany, Greece, Hungary, Ireland, Italy, the Netherlands, Spain, Sweden and the United Kingdom in Europe; Brazil, Canada, Mexico and the United States in the Americas; China, Israel, Japan, Singapore and Sri Lanka in Asia; Australia and New Zealand in Oceania; and South Africa in Africa, with worldwide delivery from China.
Contact: Felipe Iglesias, [email protected], +86 13126536955.
Verifying the metrology behind a micro part and want a supplier that will clear the file?
Send the drawing and the critical features through the contact page — the response includes the measurement plan for each tight feature, the calibration records, and the pilot quote structured to prove the measurement story.
Frequently Asked Questions
What is different about verifying a micro machining supplier?
In short, The part is small but the verification problem is large: micro features demand micro metrology, and a supplier can only be trusted if the instruments behind its reports can resolve what the drawing controls. The entity and certificate checks are the same as for any supplier; the extra layer is proving that the measurement story — not just the machining story — is real.
Which metrology questions should a micro buyer ask before paying?
In short, Ask which instrument measures each critical micro feature, how that instrument is calibrated, and what the report will show for the smallest controlled dimension. The CMM and the optical measurement system should be named, with their resolution and calibration records.
What process evidence matters most for micro parts?
In short, Reports from past micro lots showing measured values on small features, the method behind each reading, and burr and edge-control evidence where the application demands it. Micro parts hide defects easily — a burr inside a tiny feature, a residue in a small hole — so the process evidence should show the shop controls what it cannot easily rework.
How is material control handled at micro lot sizes?
In short, The same chain as any governed lot, tightened by the small quantities: the material certificate names the grade, condition, and heat; the incoming check verifies the stock against it before cutting; and the heat number travels onto the work order. Small lots do not excuse a weaker chain — they make each certificate more valuable, because one bad lot is a larger fraction of the year's supply.
What should the pilot part prove at micro scale?
In short, The pilot should prove the measurement story, not just the machining. Send a non-sensitive micro part with a real critical feature, and require the full report package with it.
How should payments be gated on a micro machining order?
In short, The same gates that protect any cross-border order, applied with the first-article evidence in the center: a deposit against the verified entity and the structured quote, the balance against the approved first article with its measurement data, and the final release against the pre-shipment check and the shipping documents. Micro parts travel in small, light consignments, so the freight leg is short but the evidence gates are the same.
Which findings should end a micro sourcing process?
In short, A metrology story that does not add up — a claimed tolerance with no instrument that can verify it, a report with no method named, or calibration records that do not exist — sits alongside the standard findings: entity shifts, certificate numbers that do not resolve, no process evidence, and payment pressure. On micro parts, a weak measurement story is a stronger finding than on macro parts, because rework is harder and defects hide more easily.
What should the RFQ carry so the quote and the delivery agree on micro work?
In short, The drawing at a named revision with the critical micro features marked, the material with its certificate requirement, the measurement method expected for each tight feature, the finish and cleanliness expectations, and the report format. Ask the supplier to confirm the process and the metrology for each critical feature in the quote.
Standards referenced on this page
- ASTM A582/A582M-12 — Standard Specification for Free-Machining Stainless Steel Bars
- ASTM B348/B348M-21 — Standard Specification for Titanium and Titanium Alloy Bars and Billets
- ISO 9001 — Quality management systems — Requirements