- ISO 9001:2015 / IATF 16949:2016 / ISO 14001:2015 — certificate numbers published and verifiable.
- Copper is bought for what it conducts. Heat and electricity, and that same softness makes pure copper gummy to machine; the free-machining grades exist to fix exactly that.
- The real constraints are work-hardening, a smeared surface on a dull edge, and preserving conductivity at joints and finishes.
- Grades in regular use: C11000 (ETP) for general electrical, C10100 (OFHC) where purity matters, C14500 (tellurium) for machinability, C12200 for plumbing-grade work.
- Incoming stock is verified against the mill certificate before it is cut.
Why copper needs its own process
Copper is bought for conductivity, not for how it machines. Pure copper is soft and ductile, so under the tool it tends to smear rather than shear, work-harden in the surface, and pick up a torn finish from a dull edge. The free-machining variants. Tellurium, sulphur, or lead-bearing coppers — break the chip and let the part cut cleanly, which is why most machined copper parts are a modified grade rather than pure tough-pitch copper. Confirm the grade on the mill certificate by XRF before cutting: an electrical-grade copper and a free-machining copper look identical and serve different purposes.
Cast and wrought copper also behave differently; cast stock carries the porosity risk of any casting, so probe before final passes on a cast blank.
Choosing a grade within copper
The grade is settled by what the part must conduct and whether it must machine. Pure grades maximise conductivity; free-machining grades trade a little conductivity for a part that cuts cleanly.
| Grade (typical) | Type | Where it is used | Machining note |
|---|---|---|---|
| C11000 | ETP (tough-pitch) | Busbars, general electrical | High conductivity; gummy, smears on a dull edge |
| C10100 | OFHC (oxygen-free) | High-purity electrical, cryogenic | Best conductivity; machined like ETP |
| C14500 | Tellurium copper | Electrical parts that must machine | Free-machining; small conductivity loss |
| C14700 | Sulphur copper | Machined electrical components | Free-machining variant |
| C12200 | DHP (phosphorous-deoxidised) | Plumbing, heat exchangers | Good form and weld; moderate cut |
| C18000 | Cu-Ni-Si (precipitation) | High-strength conductive | Harder; stronger, still conductive |
These are typical family behaviours. Conductivity is quoted relative to the annealed copper standard (IACS); the exact figure depends on temper and purity, and it is confirmed against the mill certificate.
The cutting mechanism, and what it demands
Pure copper's ductility is the problem: it deforms rather than shears, so the chip welds and smears unless the tool is sharp and the geometry is right. The response is a keen, positive-rake edge, high surface speed with a controlled feed, and rigid workholding so the soft material cannot shift. Free-machining grades behave like a proper engineering alloy and cut with a short chip. The mistake is to treat copper like brass. It is softer but far gummier, and a dull edge makes that obvious on the finish.
DFM tips specific to copper
- Pick a free-machining grade — for anything but the simplest shape, specify C14500 or a free-cutting variant; the conductivity loss is minor and the cut is dramatically better.
- Keep the edge sharp — copper finishes only as well as the tool; plan tool changes rather than stretching them.
- Rigid workholding. soft material shifts under clamping; support it so the dimension holds.
- Preserve conductivity, plating, coatings, and contaminated joints reduce the property the grade was bought for; call out clean surfaces at connection points.
- State the temper. name the specification (e.g. ASTM B152) on the drawing; the shop verifies composition by XRF.
Dimensional behaviour
Copper is dimensionally stable once machined but soft and prone to work-hardening at the surface, so light, consistent cuts beat a single heavy one on a tight feature. The general rule holds: a tolerance is held by the process, not by the machine. Where a feature is tight, the finishing pass is separated from roughing, the part is allowed to stabilise, and the measurement is taken at a controlled temperature.
Finishing and surface treatment
Copper is often left bright, lacquered to slow tarnish, or plated where wear or appearance demands it. Plating and coatings add thickness, so threaded and press-fit features need the allowance stated on the drawing. Where a coating is applied after inspection, it changes the fit, which is why the allowance belongs on the drawing, not in a closing note. For electrical contact faces, the drawing should call out a clean, uncoated finish.
Tool consumption and cycle time
Pure copper is gentle on tools but slow to cut cleanly without the right edge; free-machining grades restore normal speeds. The dominant costs are usually setup and inspection rather than the cut. The lever that matters most is still design: pocket depth, corner radius, and wall thickness change cycle time more than any tooling choice, because they determine the tool that can be used and therefore how much material can be removed per minute.
Tolerance, and the instrument behind it
Milling and turning hold ±0.003 mm (milling) / ±0.002 mm (turning); precision grinding and wire EDM hold ±0.002 mm. A tolerance is only worth as much as the instrument that verifies it, so the floor runs 20+ inspection instruments alongside the machines, CMM for dimensional and true position, vision and profile instruments for surface and geometry, hardness testers and coating gauges for plating, and XRF for incoming material composition against the mill certificate.
How much capacity sits behind it?
a hundred-odd machines with depth in every relevant family. 50+ three-axis, 20+ four-axis, 20+ five-axis, 25+ turning centres, plus Swiss-type, grinding, and wire EDM. Having several machines in that family is what lets a part re-route rather than queue when a machine is pulled for service.
What is certified, and what is deliberately not?
Three certificates, each with a number you can check with the registrar: 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 certificate excludes clause 8.3 (product design). That is normal for a build-to-print manufacturer and it is stated here rather than left for an auditor to discover: the plant manufactures to your design, it does not originate the design.
Which entity is responsible for the work?
Dongguan Zhuohang Ltd, Registration No. 91441900MA4UWT6X39, established 2005, operating as Zhuohang Precision Machining Factory. You can verify a Chinese manufacturer through the National Enterprise Credit Information Publicity System using that 18-character code; a trading company's licence will show a trading scope rather than a manufacturing one, and an office rather than a plant.
What the extra axes actually buy
The axis count is about setups, not precision. A 3-axis machine cuts from one direction, so a part with features on several faces needs to be re-fixtured between operations - and every re-fixture introduces a small error. A 4-axis machine adds rotation, and a 5-axis machine can reach five sides in one setup, so the features on several faces stay in the same coordinate frame and line up. For a part that is a prismatic block, 3-axis is enough and cheapest; for a part with angled or multi-face features, the extra axes buy accuracy and fewer operations. You choose the axis count for the geometry, not by habit.
How to read an axis-based quote
If a part genuinely needs 5-axis work, the quote reflects one setup and tighter feature relationships; if a shop puts a 3-axis part on a 5-axis machine and charges for it, you are paying for capability the geometry does not use. This floor runs 3-, 4- and 5-axis machines including the Mazak VARIAXIS I-600 five-axis and the INTEGREX I-250H S mill-turn, at ±0.003 mm milled. Contact Felipe Iglesias at [email protected] or +86 13126536955 with the drawing and ask which axis count the geometry actually justifies.
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). Cut on 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). Cut on 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). Cut on 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). Cut on shafts, bushings, flanges up to ±0.002 mm.
- Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Cut on 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.
Send a drawing and get a manufacturability read
Upload your model for a quote, or arrange a factory audit with [email protected] or +86 13126536955. Ask for Felipe Iglesias.
Frequently Asked Questions
What files do you need for a quote?
In short, A 3D model (STEP or IGES) with a 2D drawing carrying the tolerances, surface finish callouts, material spec and any inspection or certification requirements. The drawing defines the contract — the model alone usually leaves the tolerance scheme unspecified.
How is an engineering change handled mid-production?
The change is documented against a revision, the affected parts in process are identified, and the revised drawing is confirmed in writing before work restarts. The important part is that the revision in force at any moment is a single, written one.
Does stainless steel cost more to machine than aluminium?
Usually yes, and the reason differs by material: for titanium it is cutting speed and tool consumption, for stainless it is cycle time and work-hardening management. The lever that matters most is usually design depth rather than process choice.
How is material traceability maintained?
Incoming stock is checked against the mill certificate — composition by XRF, hardness where specified — and traceability is held per heat or per batch as the certificate defines it.
Are you a manufacturer or a trading company?
A manufacturer. The registered entity is Dongguan Zhuohang Ltd (No. 91441900MA4UWT6X39), a 6,800 m² facility with 100+ machines and 100+ staff in Dongguan, open to factory visits.
What materials do you machine?
Aluminum, stainless steel, titanium, brass, copper, and Inconel for metals; PEEK and Delrin (POM) for plastics. Material certificates are verified on incoming stock.
Do you certify stainless steel material?
Yes. Material certificates are supplied with the parts and incoming stock is checked against the mill certificate — composition by XRF, hardness where specified. Traceability is per heat or per batch as the certificate defines it.
Do you certify copper material?
Yes. Material certificates are supplied with the parts and incoming stock is checked against the mill certificate — composition by XRF, hardness where specified. Traceability is per heat or per batch as the certificate defines it.
Which copper grade machines best?
In short, The free-machining grades such as C14500 (tellurium copper) machine like a proper engineering alloy and are the usual choice for anything beyond the simplest shape. Pure ETP or OFHC copper conducts better but smears under the tool, so the choice is conductivity versus machinability and should be named on the drawing.
Is your IATF 16949 certificate valid for design work?
No. The certificate excludes clause 8.3 (product design). The plant is certified to manufacture to your design and to run the associated process controls, not to originate product design.
Can you work to ASME Y14.5 as well as ISO?
Yes. Both geometric dimensioning conventions are used. The important thing is that the drawing states which one applies, because a single symbol is not interpreted identically under the two standards.
Continue reading: 4 Axis CNC Machining · 5 Axis CNC Machining
Standards referenced on this page
- ASTM A582/A582M-12 — Standard Specification for Free-Machining Stainless Steel Bars
- ASTM A484/A484M-24 — Standard Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings
- ISO 9001 — Quality management systems — Requirements