- Ppk ≥ 1.67 initial on key characteristics — a measured chart in the record. ±0.003 mm CNC milling, ±0.002 mm CNC turning; ±0.002 mm grinding, logged on CMMs.
- XRF material checks become the first link in the traceability chain.
- MES/ERP records — every check stored and retrievable per lot.
How does the quality system feed the traceability chain?
Quality and traceability are one system. Every quality check writes to the MES/ERP record: SPC charts, CMM measurements, XRF results, and pass/fail outcomes all land in the same chain. The quality system produces the evidence, and the traceability chain is where the evidence is stored and retrieved. A quality claim without a log is an assertion; with a log, it is a fact you can pull up on demand.
The two have to be one system, or the record breaks. If quality data lived in a separate spreadsheet from the production record, the link between "this part was measured" and "this part was shipped" would be a manual join that gets dropped under load. Writing every check to the same MES/ERP chain keeps the evidence and the part in the same file, which is what makes the chain trustworthy.
What process capability does the shop hold?
Process capability is the number that tells you the process is in control, and it is recorded, not recited. Key characteristics are held at Ppk ≥ 1.67 initial, general characteristics at Cpk ≥ 1.33. On a representative length characteristic, the SPC records Cpk = 1.851 (one characteristic on one part, not a blanket capability claim) — a measured chart that is also part of the traceability record, retrievable for any lot it belongs to.
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.
| Capability level | What it tells a buyer |
|---|---|
| Ppk ≥ 1.67 initial (key characteristics) | The process holds the dimension with margin, so a drift is caught before it reaches the limit |
| Cpk ≥ 1.33 (general characteristics) | The process is in control for routine dimensions |
| Cpk = 1.851 (one characteristic on one part, not a blanket capability claim) (measured, representative length) | A recorded chart on a real characteristic, retrievable per lot |
The distinction between key and general characteristics matters. Key characteristics are the dimensions where a failure is dangerous or expensive — a bearing seat, a sealing face — and they are held tighter and watched closer. General characteristics are everything else, held in control but with less margin needed. The record tracks both, so you know which dimensions were treated as critical and which were not.
How are tolerances verified and logged?
A tolerance is verified on a CMM and logged to the chain — the two steps go together.
| Process | Held tolerance | Verification |
|---|---|---|
| CNC milling | ±0.003 mm | Hexagon GLOBAL S CMM |
| CNC turning | ±0.002 mm | Hexagon GLOBAL S CMM |
| Precision grinding | ±0.002 mm | CMM plus surface-finish / profile instruments |
The measurement is not a one-time event; it is an entry in the record, tied to the lot, so the tolerance you were promised is the tolerance you can see in the chain. A dimension is verified, then logged, then retrievable — three steps that turn a tolerance from a claim into evidence.
How does SPC work on the floor?
SPC — statistical process control — is the quality system's early warning. As parts are measured, control charts are plotted on key characteristics, and a drift shows up as a trend on the chart long before it produces an out-of-tolerance part. The operator sees the trend, corrects the process, and the drift is caught before it becomes scrap. The charts themselves are logged to the lot record, so the process history and the part history are the same file.
This is where quality stops being reactive and becomes predictive. Without SPC, you find out about a problem when the parts fail inspection; with it, you see the problem coming in the chart. The Cpk value is the summary of those charts — a single number that says how much margin the process has left before it hits the tolerance limit. A logged Ppk ≥ 1.67 at the initial study on key characteristics is not a boast; it is a measurement with the charts to back it.
How is the raw material link verified?
The raw material is the first link in the chain, and it is verified before anything else happens. Every incoming lot is XRF-checked against its mill certificate, and that verification becomes the first entry in the traceability record. The material link is measured, not just labeled, so a substituted alloy is caught at the door and never enters the chain under a false identity.
The material verification does not stop at chemistry. Hardness and tensile testing confirm the material is in the right condition, not just the right alloy — a 4140 shaft that was never heat-treated is a different part than one that was, and chemistry alone cannot tell them apart. The quality system records both, so the material link covers composition and condition.
How does traceability make a non-conformance isolatable?
The whole point of the chain is to answer "where did this come from" in one query. The MES/ERP record identifies the exact lot, machine, operator, and raw material for any part, so a non-conformance is quarantined to the affected lot. The rest of the run keeps its value and its schedule. Without the chain, the same event is a full recall; with it, it is a local correction.
The isolation is what protects your schedule. A hold on one lot means the other lots in the order keep moving, and you rework or scrap only the affected parts. That is the difference between a supplier who hands you a problem and a supplier who hands you a problem already contained — the chain does the containment before you ever hear about it.
How does the quality system handle a non-conformance?
When a non-conformance happens, it is not waved through; it is written up. The affected lot is quarantined against its record, the root cause is found — a worn tool, a drifted offset, a bad heat — and the corrective action is logged back into the chain. The disposition, whether rework, scrap, or concession, is recorded too. So the non-conformance becomes another entry in the record, and the same problem does not have to be solved twice.
For you, this is what separates a quality system from a sorting operation. A sorter finds bad parts and throws them away; a quality system finds bad parts and fixes the process that made them. The corrective-action log is the evidence of which one you are dealing with, and it is part of the chain you can audit.
What inspection equipment verifies dimensions?
The inspection bench covers the full range of verification, and every instrument's result lands in the record. Hexagon GLOBAL S CMMs, vision measuring machines, a gear measuring center, and surface-finish and profile instruments verify dimensions; micro-Vickers hardness, Fischer coating thickness, salt spray, and tensile testers cover material and coating properties. Each result is a link in the chain.
The equipment matters because it defines what can be verified rather than assumed. A CMM verifies a bore to microns; a vision machine measures features a contact probe cannot reach; a gear measuring center checks tooth geometry that a generic CMM cannot. When the drawing calls out a feature, the right instrument has to exist to measure it, and the reading has to be logged. The bench and the record together are the inspection link.
How does the quality system document surface finish and coatings?
Surface finish and coatings are measured, not eyeballed. Roughness is recorded as Ra in micrometers — Ra 3.2 for as-milled, Ra 1.6 for standard machined, Ra 0.8 for fine and sealing surfaces — and the reading is logged to the lot. Coating thickness is measured with a Fischer gauge, and the result is recorded against the specification. Salt spray testing confirms corrosion resistance where the drawing calls for it.
The surface is where a part fails most often, so it is where the quality record earns its keep. When a sealing surface leaks or a coating wears through early, the answer should be a logged roughness reading or a measured thickness, not a description of how the part was "finished." The chain turns surface quality from an adjective into a number you can hold a supplier to.
How does the quality system support a first-article or PPAP?
A first-article report is the quality system's opening deliverable, and it is built from the same record the rest of the chain uses. The first part off the process is fully dimensioned, its results are logged against the drawing, and that record becomes the baseline the run is held to. For automotive work, the same data feeds the PPAP documentation — the process capability studies, the control plan, the dimensional results — because the record already contains them.
The point is that a first-article or a PPAP is not a separate document you have to commission; it is the traceability record, formatted for a specific purpose. A shop that runs the chain on every job can produce either on demand, because the underlying data is already logged. That is the difference between a quality system and a paperwork exercise — one produces the record as it works, the other assembles it when asked.
Which certifications back the quality system?
Certification means the record exists and is auditable — the chain is not optional, it is part of what the certificate verifies.
| 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 — a build-to-print operation, which keeps the traceability unambiguous about who owns each link.
How do you audit the traceability chain from a distance?
Request three things: the XRF material record for a recent lot, a CMM report or SPC chart from a real job, and the traceability record that ties the two together — raw material to finished part. A supplier that returns all three is one whose chain you can file; one that hesitates is one whose chain has a gap somewhere. The record is documented, so it can be reviewed remotely, before you ever set foot in the factory.
- Ask for the XRF record on a recent incoming lot, not a generic material statement.
- Ask for a CMM report or SPC chart from a real job, and check it is dated and tied to a lot.
- Ask for the MES/ERP record that joins the material, process, and inspection links.
- Confirm the Cpk claim is a measured chart you can see, not a number recited from memory.
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). Typical work: 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). Typical work: 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). Typical work: 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). Typical work: shafts, bushings, flanges up to ±0.002 mm.
- Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Typical work: 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.
Audit the traceability chain behind your part.
Send your drawing to [email protected] or call +86 13126536955 for XRF, CMM, and MES/ERP records from a real job.
Frequently Asked Questions
How does the quality system feed the traceability chain?
Every quality check writes to the MES/ERP record: SPC charts, CMM measurements, XRF results, and pass/fail all land in the same chain. The quality system is the evidence, and the traceability chain is where the evidence is stored and retrieved.
What process capability does the shop hold?
In short, Key characteristics are held at Ppk ≥ 1.67 initial and general characteristics at Cpk ≥ 1.33. On a representative length characteristic the SPC records Cpk = 1.851 (one characteristic on one part, not a blanket capability claim) — a measured chart that is also part of the traceability record.
How is the raw material link verified?
Every incoming lot is XRF-checked against its mill certificate before it reaches a machine, and that verification becomes the first entry in the traceability record. The material link is measured, not just labeled.
How does traceability make a non-conformance isolatable?
The MES/ERP record identifies the exact lot, machine, operator, and raw material for any part, so a non-conformance is quarantined to the affected lot. The rest of the run keeps its value instead of being recalled whole.
What inspection equipment verifies dimensions?
Hexagon GLOBAL S CMMs, vision measuring machines, a gear measuring center, and surface-finish and profile instruments verify dimensions, with each result logged to the chain. Micro-Vickers hardness and coating thickness cover material properties.
Which certifications back the quality system?
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). IATF 16949 excludes product design under Clause 8.3 — a build-to-print operation.
How does SPC work on the floor?
Control charts are plotted on key characteristics as the parts are measured, so a drift shows up as a trend before it becomes a non-conformance. The charts are logged to the lot record, so the process history and the part history are the same file.
How does the quality system handle a non-conformance?
A non-conformance is written up, the affected lot is quarantined against its record, the root cause is found, and the corrective action is logged back into the chain. The record is what keeps the same problem from having to be solved twice.
Custom Machined Part Quality — Related Pages
Continue reading: Custom Machined Part Factory · Custom Machined Part Services · Custom Machined Parts Manufacturer
Standards referenced on this page
- ASTM A582/A582M-12 — Standard Specification for Free-Machining Stainless Steel Bars
- ISO 14001 — Environmental management systems — Requirements with guidance for use
- IATF 16949:2016 — Automotive quality management system standard