- Ppk ≥ 1.67 initial on key characteristics; a real run shows Ppk ≥ 1.67 at the initial study on key characteristics.
- Hexagon CMMs verify critical dimensions.
- XRF material verification at incoming inspection.
- ISO 9001 · IATF 16949 · ISO 14001.
- Full lot traceability via MES/ERP.
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.
Why does quality affect lead time?
A process that produces scrap is also a process that produces delay — rework, re-measurement, and rescheduling all eat the calendar. The cheapest way to shorten lead time is to get it right the first time, which is what a quality system is for. Quality and schedule are the same discipline.
The connection is direct and quantifiable in the abstract: every rejected part is a part that must be made again, which doubles its calendar and steals capacity from the next order. Every re-measurement is an inspection gate the part runs twice. Every non-conformance that is caught late — at final inspection instead of at the first article — is a whole batch at risk instead of a single setup. A quality system is therefore not a cost center bolted onto manufacturing; it is the cheapest scheduling tool a shop owns, because it removes delay at the source rather than chasing it after the fact.
The buyer who treats quality and lead time as separate is paying for both. The supplier who treats them as one discipline can quote a shorter tier honestly, because it does not need to pad the schedule against the scrap it knows it will produce.
Which certifications back the quality system?
| 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.
How are dimensions verified before shipping?
- Hexagon GLOBAL S CMMs (2) for dimensional verification, plus vision measuring machines and a gear measuring center.
- KEYENCE VK-X3000 laser microscope and SURFCOM 1800D for surface finish and profile.
- XRF (iCHEQ) spectrometer for incoming material composition checks against the mill certificate.
- HVS-1000A micro-Vickers hardness tester, Fischer coating thickness gauge, salt spray and tensile testers.
- SPC: control charts on key characteristics, with Ppk ≥ 1.67 at the initial study on critical characteristics and Cpk ≥ 1.33 in production on general characteristics.
How is process capability measured?
| Characteristic class | Cpk target | What it means |
|---|---|---|
| Key characteristics | ≥ 1.67 | The process is stable and centered well inside the tolerance band |
| General characteristics | ≥ 1.33 | The process meets standard capability expectations |
On a representative length characteristic (76.1–76.5 mm), our SPC shows Cpk = 1.851 (one characteristic on one part, not a blanket capability claim), demonstrated on a real job.
The index is worth reading correctly, because a capability number without its context is a slogan. Cpk compares the process spread against the tolerance band and penalises a process that is stable but sitting off center, which is why a process can be repeatable and still fail the index. When any supplier hands you a capability figure, ask three questions: which characteristic, how many subgroups, and which instrument produced the data. A number with those three attached is evidence; without them it is arithmetic on unknown measurements.
How is incoming material verified?
Every incoming lot is checked by XRF spectrometer against its mill certificate before it reaches a machine. Catching a substituted alloy at the door prevents a field failure, and the rework and delay that would follow it.
The timing of the check is the whole point. A material problem found at goods-in costs a phone call and a replacement bar; the same problem found after machining costs a scrapped batch and a repeated schedule. The XRF reading is paired with the mill certificate so the grade on the paperwork and the grade in the bar are the same thing, and hardness is confirmed on the HVS-1000A micro-Vickers tester where the print specifies a condition. Verification before cutting is the cheapest insurance a precision order can buy.
How are parts traced back to the raw material?
Our MES/ERP system records raw material source, process parameters, machine data, batch, machining time, operator, and inspection results on every lot, so a non-conformance can be isolated, not guessed at.
Traceability protects the schedule in a specific way: when a problem is found, it can be contained to one lot instead of quarantining everything the shop has made. Without a lot record, a single suspect part forces a broad recall of similar parts and a re-audit of the whole process; with one, the question "which material, which machine, which operator, which batch" is answered in minutes instead of weeks. That is the difference between a supplier that stops the line for one lot and one that stops it for a month.
What documentation ships with a quality part?
- CMM dimensional reports for critical dimensions.
- SPC control charts for process-critical characteristics.
- Material certificates, with the XRF verification behind them.
- PPAP / FAI packages for automotive and regulated work.
How inspection gates are placed to catch problems early
Where inspection happens matters as much as what it measures, because a problem found early costs a corrected setup while a problem found late costs a scrapped batch. The gates on this floor are placed at the points where a part can still be saved: goods-in for material, first article off a new setup before the batch runs, and control charts through the run so tool wear appears as a trend rather than as a failed final inspection.
- Goods-in — XRF against the mill certificate, so the wrong alloy never reaches a machine.
- First article — the first part off a new setup is measured on a Hexagon GLOBAL S CMM before the batch continues, the cheapest place to catch a program or fixture problem.
- In-process SPC — control charts on key characteristics, so drift is corrected before a limit is crossed.
- Pre-dispatch — final inspection compiles the documents that ship with the lot.
The placement is what turns quality into schedule protection. A shop that only inspects at the end is not saving inspection cost; it is moving the cost of every defect to the point where it is most expensive, and the delay lands on the delivery date instead of on a mid-run correction.
How the capability numbers are actually produced
A capability index is arithmetic performed on measurements, so it is only as good as the measurements and the sampling behind it. Parts are measured in subgroups as the batch runs, not once at the end. Each subgroup gives an average and a spread; the averages show whether the process is drifting and the spread shows how much natural variation the process has. Cpk compares that variation with the tolerance band and penalises a process that is stable but sitting off center, which is why a process can be repeatable and still fail the index.
Targets here are Ppk ≥ 1.67 at the initial study on critical characteristics and ≥ 1.33 on general characteristics. The recorded example is a length characteristic between 76.1 and 76.5 mm, where the value reached 1.851 (one characteristic on one part, not a blanket capability claim) across 25 subgroups. When you receive a capability figure from any supplier, ask three questions: which characteristic, how many subgroups, and which instrument produced the data. A number without those three is a slogan rather than evidence.
Measurement uncertainty, datums, and why two labs disagree
Most disputes about a few micrometres are not disagreements about machining. They come from three sources that are easy to eliminate before a batch ships.
- Gauge capability. A measurement system should resolve far finer than the band it judges, roughly by ten to one. A ±0.003 mm (milling) / ±0.002 mm (turning) feature belongs on a Hexagon GLOBAL S CMM, not on a hand gauge, because gauge variation would otherwise consume much of the tolerance.
- Datum choice. A part located on different surfaces measures differently, and both results can be correct. A drawing that names datums removes the argument; a drawing with only sizes invites it.
- Temperature. Dimensional measurement references 20 °C. Aluminum moves roughly 23 micrometres per meter per degree Celsius, so a warm part and a cold bench can differ by more than the tolerance on a long feature.
Agreeing the datum scheme, the instrument and the reference condition in advance costs one email. Discovering that you and your supplier measured differently costs a batch and a relationship.
When measurement happens, and why the order matters
Inspection is placed at the points where a part can still be saved. Material is verified at goods-in by XRF against the mill certificate, with hardness confirmed on the HVS-1000A where condition is specified, because machining the wrong grade well is still scrap. The first part off a new setup is measured before the batch continues, which is the cheapest place to catch a program or fixture problem. Key characteristics are then tracked on control charts through the run, so tool wear appears as a trend rather than as a failed final inspection.
Features that will be coated are measured with the coating question already settled, since plating and anodizing add thickness on toleranced surfaces and a Fischer gauge is used to confirm what was added. Final inspection compiles the documents that ship with the lot: CMM reports for critical dimensions, SPC charts for tracked characteristics, material certificates with the XRF verification behind them, and PPAP or FAI packages on request for automotive and regulated work. Every lot keeps a record in the MES and ERP system covering material source, process parameters, machine data, batch, machining time, operator and inspection results.
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). Applications: 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). Applications: 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). Applications: 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). Applications: shafts, bushings, flanges up to ±0.002 mm.
- Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Applications: 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.
Send your drawing for a quote.
Email [email protected] or call +86 13126536955 for a review and quote.
Frequently Asked Questions
What certifications do you hold?
ISO 9001:2015 (No. 116024/A/0001/UK/En), IATF 16949:2016 (No. 131941/A/0001/SM/En), and ISO 14001:2015 (No. 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 dimensions?
Critical dimensions are checked on Hexagon GLOBAL S CMMs, supported by vision measuring machines and a gear measuring center. We hold process capability to Ppk ≥ 1.67 at the initial study on key characteristics.
How do you verify incoming material?
Every incoming lot is checked by XRF spectrometer against its mill certificate before it reaches a machine. This catches substituted or mixed alloys at the door, so the material you specified is the material that actually gets machined.
Do you provide inspection reports?
Yes. CMM dimensional reports, SPC charts, and material certificates ship with your parts. For automotive and regulated work we can also run PPAP and FAI packages on request.
What is your process capability standard?
In short, We target Ppk ≥ 1.67 at the initial study on key characteristics and ≥ 1.33 on general characteristics. On a representative length characteristic our SPC shows Cpk = 1.851 (one characteristic on one part, not a blanket capability claim), measured over 25 subgroups.
How do I request quality documents?
Email [email protected] and specify which documents you need — certificates, a CMM report sample, an SPC chart, or a PPAP package. We provide documentation that matches the part.
How do inspection gates protect my delivery date?
In short, Inspection is placed where a part can still be saved — material at goods-in, first article off a new setup, and control charts through the run. A problem found early costs a corrected setup; the same problem found at final inspection costs a scrapped batch and a repeated schedule.
How does a rejected part affect the schedule?
In short, Every rejected part must be made again, which doubles its calendar and steals capacity from the next order. A quality system that catches defects at the first article, rather than at final inspection, is what keeps a single bad setup from becoming a slipped delivery date.
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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