- XRF material verification on every incoming lot against the mill certificate. ±0.003 mm CNC milling, ±0.002 mm CNC turning, ±0.002 mm grinding, verified on Hexagon CMMs.
- Cpk 1.851 (one characteristic on one part, not a blanket capability claim) measured on a representative length feature, against a target of Ppk ≥ 1.67 initial.
- ISO 9001, IATF 16949, ISO 14001 — three certificates with verifiable numbers.
Read the tolerance band before you read the index. Cpk is a ratio of the tolerance band to the process spread, not an absolute measure of accuracy. The figure above was recorded on a length characteristic with a 0.4 mm band (76.1–76.5 mm) — wide by design. Hold the same process spread against a ±0.005 mm feature and it fails outright. Ask for the band, the subgroup count and the sampling window on every capability number a supplier quotes.
How does quality verification start with the material?
Quality on a machined part begins before the machine turns on, because the cheapest place to fail a part is the incoming stock. A bar of stainless that is actually mild steel will machine beautifully, pass a dimensional check, and then fail in service, and no amount of post-machining inspection recovers that. The first quality gate is therefore material identity, and it is the gate most buyers never ask about.
Ask any shop — including this one — one question: how do you verify the alloy before you cut it? The answer separates a manufacturer from a trading desk. A real manufacturer checks the incoming lot against its mill certificate with a handheld XRF spectrometer and can show you the result. That single step protects you from the most expensive failure mode in custom machining: a part made from the wrong material that looks right and behaves wrong.
How is incoming material checked before machining?
Every incoming lot is tested with a handheld XRF spectrometer and compared against its mill certificate before it goes on a machine. XRF identifies the alloy composition non-destructively in seconds, which is enough to catch a mixed or mislabeled lot at the door instead of in your assembly. The result is tied to the lot, and the lot travels through the MES/ERP system for the rest of the run.
Why this matters for the material decision: if your drawing calls out 316L for a corrosion-critical fitting, XRF verification is what makes that "316L" real. Without it, the callout is a hope. With it, the alloy you specified is the alloy that gets cut, and if a lot ever fails in service, the traceability tells you exactly which material, which batch, and which run.
What tolerances does the shop hold, and how are they verified?
A tolerance printed on a website is marketing; a tolerance verified on a CMM is a capability. We hold ±0.003 mm on CNC milling, ±0.002 mm on CNC turning and ±0.002 mm for precision grinding, and every critical dimension is measured on a Hexagon GLOBAL S coordinate measuring machine rather than assumed from the machine's own readout.
| Process | Held tolerance | Verification |
|---|---|---|
| CNC milling | ±0.003 mm | Hexagon CMM |
| CNC turning | ±0.002 mm | Hexagon CMM |
| Precision grinding | ±0.002 mm | Hexagon CMM + profilometer |
The measurement equipment is the same class a buyer would use to audit us: two Hexagon GLOBAL S CMMs, vision measuring machines, a gear measuring center, a KEYENCE laser microscope, and a SURFCOM profilometer. When a dimension drifts, we see it on our own instruments the same day, not weeks later through a subcontracted lab.
What does Cpk tell you about process control?
Cpk is the number that tells you whether a process holds a dimension consistently inside its tolerance, not just on one lucky part. A high Cpk means the process runs comfortably within limits; a low Cpk means it is scraping the edge of the tolerance and a small drift will produce scrap.
Our standard is Ppk ≥ 1.67 at the initial study on key characteristics and Cpk ≥ 1.33 on general ones. On a representative length characteristic — a 76.1–76.5 mm feature across 25 subgroups of four parts — our SPC shows Cpk = 1.851 (one characteristic on one part, not a blanket capability claim), comfortably above the key-characteristic target. That is not a brochure number; it is a control chart from a real job, and it is the kind of evidence you should ask any shop to produce.
What Cpk means for your order: a process running at Cpk 1.85 produces parts that stay well inside tolerance, which is what keeps a batch consistent between the first article and the last piece — the failure mode that hurts most when it is missing.
How are surface finishes and heat treatment verified?
The finish is the part of the quality chain most likely to be inspected by eye and least likely to be measured, and that is exactly where problems hide. A coating that is too thin will corrode; a surface that is too rough will wear its mating part. So the finish gets measured, not admired.
- Surface finish and profile are checked with a KEYENCE VK-X3000 laser microscope and a SURFCOM 1800D profilometer.
- Coating thickness is measured with a Fischer gauge, so a plated or anodized layer is verified to thickness, not assumed.
- Hardness after heat treatment is checked with an HVS-1000A micro-Vickers tester.
- Corrosion resistance is verified with a salt spray chamber, and mechanical strength with a tensile tester.
This is where the material decision and the finish decision meet the quality system. Anodize the wrong alloy and the finish fails; heat-treat to the wrong hardness and the part wears. Measuring the finish closes the loop that the material selection opened.
Which certifications back the quality system?
Certifications are a pre-audit — they tell you a shop already runs a documented system that a third party has checked. We hold three, with scope stated honestly rather than inflated.
| Standard | Certificate number | Scope |
|---|---|---|
| ISO 9001:2015 | 116024/A/0001/UK/En | Machining of metal parts |
| IATF 16949:2016 | 131941/A/0001/SM/En | Manufacture of CNC metal machining parts (excludes product design, Clause 8.3) |
| ISO 14001:2015 | 116024/B/0001/UK/En | Environmental management related to machining of metal parts |
Honest scope note: IATF 16949 excludes product design under Clause 8.3. We are a build-to-print manufacturer — if your program needs us to own design responsibility, say so up front and we will scope it accordingly rather than over-promise.
How are parts traced back to their material and process?
For automotive and regulated buyers, traceability is not optional — it is the difference between isolating a problem and guessing at it. Our MES/ERP system records the full chain on every lot: raw material source and usage, process parameters, machine data, production batch, machining time, operator, and inspection results. If a non-conformance ever surfaces, we can tell you which lot, which machine, and which operator, and contain the impact instead of scrapping the whole shipment to be safe.
This is the same discipline IATF 16949 audits look for, and it runs on every job, not just automotive ones. The material verification at the door and the traceability through the run are two halves of the same promise: you know what your parts are made of, and you know how they were made.
What documentation ships with your parts?
The documentation is the deliverable that proves the quality system actually ran. With your parts you receive CMM inspection reports, SPC control charts, material certificates, and any customer-required documents such as a first-article report or PPAP package. This is the difference between a supplier that claims quality and one that hands you the evidence to verify it yourself.
- Ask for the certificate numbers, not the logos. Real certificates have numbers you can check with the registrar.
- Ask to see a real control chart. A shop running SPC can show one from a real job, not a template.
- Ask how material is verified. XRF at the door, or trust?
- Ask for the inspection report before the parts ship. If a dimension failed, you want to know before the box is in transit.
What is a first article inspection, and why does it matter?
A first article inspection (FAI) measures one part, complete, against the full drawing before the batch runs. It is the proof that the material, the process, and the finish all delivered what the drawing asked, and it is the moment to catch a wrong assumption before it becomes a wrong shipment.
The FAI checks three things in order. The material is confirmed against the mill certificate and the XRF result. The geometry is measured on a CMM, dimension by dimension, not sampled with calipers. The finish is checked for roughness, coating thickness, and hardness where they apply. When all three pass, the process is released and the rest of the batch runs to the same settings.
How do you read an SPC control chart?
A control chart is the difference between a shop that inspects quality in and one that controls it in. It plots a measured dimension over time, with control limits drawn from the process's own behavior. Points inside the limits mean the process is stable; points drifting toward a limit mean trouble is coming before it produces a bad part.
The number that summarizes the chart is Cpk — how consistently the process stays inside the tolerance, not just on one lucky part. We target Ppk ≥ 1.67 at the initial study on key characteristics and Cpk ≥ 1.33 on general ones, with a measured example of Ppk ≥ 1.67 at the initial study on key characteristics on a length feature. A chart that can be produced on demand, from a real job, is the evidence you should ask for in place of a pass/fail claim.
What does measurement uncertainty mean for a ±0.003 mm (milling) / ±0.002 mm (turning) part?
A tolerance like ±0.003 mm (milling) / ±0.002 mm (turning) is only as honest as the instrument that checks it. If a caliper can barely resolve the tolerance band, the measurement itself is a guess, and the shop is reporting confidence it does not have. That is why critical dimensions are measured on CMMs — coordinate measuring machines with far finer resolution than the tolerances they verify.
The same logic runs through the whole inspection bench. Surface roughness is measured with a profilometer and a laser microscope, not felt with a thumbnail. Coating thickness is measured with a gauge, not estimated. Hardness is measured with a tester, not assumed. When the instrument is finer than the tolerance, the number means something; when it is not, the number is decoration.
What this shop actually runs
Capability evidence should come as specifics, not slogans. Behind this guide is a 6,800 m2 plant in Dongguan, China running 100+ CNC machines with 100+ staff. The machine list 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). Built 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). Built 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). Built 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). Built for shafts, bushings, flanges up to ±0.002 mm.
- Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Built 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: ±0.003 mm CNC milling / ±0.002 mm CNC turning / ±0.002 mm grinding and wire EDM. Capability: Ppk >= 1.67 initial on key characteristics, Cpk >= 1.33 ongoing.
Certificates: ISO 9001:2015 (116024/A/0001/UK/En), IATF 16949:2016 (131941/A/0001/SM/En, with design clause 8.3 excluded, stated openly) and ISO 14001:2015 (116024/B/0001/UK/En), issued to Dongguan Zhuohang Ltd, registration 91441900MA4UWT6X39, founded 2005.
Where we ship: 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 — plus other countries and regions worldwide, shipped from our base in Dongguan, China.
Contact: Felipe Iglesias, [email protected], +86 13126536955.
Want your parts backed by measurement, not promises?
Send your drawing to [email protected] or call +86 13126536955 for a quote with inspection evidence.
Frequently Asked Questions
Are you ISO and IATF certified?
Yes. We hold ISO 9001:2015 (116024/A/0001/UK/En), IATF 16949:2016 (131941/A/0001/SM/En), and ISO 14001:2015 (116024/B/0001/UK/En). The IATF 16949 scope excludes product design under Clause 8.3, so we are a build-to-print manufacturer.
How do you verify the material is what I ordered?
Incoming raw stock is checked with a handheld XRF spectrometer against the mill certificate before it reaches a machine. This catches mixed or mislabeled lots at the door, so the alloy you specify is the alloy that gets cut.
What is Cpk and why does it matter for machined parts?
In short, Cpk measures how consistently a process holds a dimension inside its tolerance. A higher Cpk means the process stays comfortably within limits.
Do you provide inspection reports with the parts?
Yes. CMM inspection reports, SPC charts, material certificates, and other documentation ship with your parts, so you receive documented evidence of what the parts are made from and how they measure rather than a pass/fail claim.
How do you verify surface finish and coating thickness?
In short, Surface finish and profile are checked with instruments including a KEYENCE laser microscope and a SURFCOM profilometer, and coating thickness is measured with a Fischer gauge. Salt spray and tensile testers verify corrosion and mechanical performance.
What inspection equipment do you run?
Two Hexagon GLOBAL S CMMs, vision measuring machines, a gear measuring center, a KEYENCE laser microscope, a SURFCOM profilometer, a micro-Vickers hardness tester, an XRF spectrometer, a Fischer coating gauge, and salt spray and tensile testers.
What is a first article inspection?
A first article inspection measures one part, complete, against the full drawing before the batch runs. It confirms the material, the geometry, and the finish in order, so a wrong assumption is caught before it becomes a wrong shipment.
How do I know a tolerance is being measured, not assumed?
In short, Ask what instrument checks the dimension. Critical dimensions are measured on CMMs with far finer resolution than the tolerance they verify, and surface roughness and coating thickness are measured with a profilometer and a gauge.
Custom Machining Parts Quality — Related Pages
Standards referenced on this page
- IATF 16949:2016 — Automotive quality management system standard
- ASTM A582/A582M-12 — Standard Specification for Free-Machining Stainless Steel Bars
- ISO 14001 — Environmental management systems — Requirements with guidance for use