- ISO 9001:2015 / IATF 16949:2016 / ISO 14001:2015. certificate numbers published and verifiable.
- The dividing line is microstructure: machining cuts from certified wrought stock; casting solidifies molten metal in a mould.
- Machining wins on tolerance, certification, and low-volume flexibility; casting wins on complex hollow geometry and high-volume tooling amortisation.
- The cost curves cross, not at a fixed quantity, but where the casting's pattern/mould cost is paid back by per-part savings.
- In either route, the part is built to your drawing; the plant does not originate the design.
The dividing line is the microstructure
Machining starts from bar, plate, or billet that was already rolled or forged. Its grain runs through the part and its properties are the mill's published, certifiable values. Casting starts from molten metal that solidifies in a mould, which means a new microstructure with a solidification front, shrinkage, and the possibility of porosity. Neither is "better"; they answer different questions. A part that must carry a certified material specification is usually machined from wrought stock; a part whose value is a hollow, organic, or very large shape is usually cast.
The honest way to frame the choice is not "which is more advanced" but "which side of the tolerance, certification, and quantity line does this part fall on".
Why the two differ in properties, cost, and lead time
Properties. Wrought stock gives isotropic, certifiable properties traceable to a mill heat or batch. A casting's properties depend on how it solidified — directionally stronger along the chill, weaker across a shrink zone, and locally variable where porosity sits. Critical castings are qualified by NDT (X-ray, dye-penetrant) that a machined part from certified stock does not need.
Cost. Machining carries a fixed cost, programming, fixturing, first-article inspection. And a low, volume-falling variable cost. Casting carries a large fixed cost — pattern, tooling, and often a mould qualification — and a lower per-part cost once that is amortised. The curves cross where the casting's tooling is paid back, and that point moves with part size, material, and tolerance.
Lead time. Machining's lead is mostly queue, fixture design, and first-article inspection. Casting's lead is mostly tooling and Mold qualification before the first good part; after that, per-part time is short. Ask for first-article and repeat lead separately from either route.
Quantified comparison
| Factor (typical) | 3 Axis CNC Machining | Casting (sand / die) |
|---|---|---|
| Dimensional tolerance±0.003 mm CNC milling / ±0.002 mm CNC turning; ±0.002 mm grind | ±0.5 mm (sand) to ±0.1–0.3 mm (die), then often machined | |
| Material certification | Wrought stock, traceable to mill cert | Cast lot; porosity/NDT control needed for critical parts |
| Material utilisation | Low. Swarf is removed stock | Higher — near-net, but sprue/gate is waste |
| Geometry freedom | Limited by tool access | Hollow sections, undercuts, organic shapes |
| Tooling cost | Fixture / programme, low–moderate | Pattern + mould/die, high (die casting very high) |
| As-finished surface | Ra ~0.8–3.2 µm, may need no post | Rougher; functional faces usually machined |
| Best quantity band | Prototype through production | Medium–high volume once tooling amortised |
| First-article lead | Days to weeks (programme + fixture) | Weeks (tooling + mould qualification) |
The figures above are typical bands, not guarantees — sand casting and die casting are different processes, and a casting that needs its interfaces machined carries both costs. Confirm the numbers for your specific part at quote stage.
Decision checklist
- Choose machining if the part needs a tight tolerance or a certified wrought material, is prismatic, is needed in low or medium volume, or must iterate quickly without amortising tooling.
- Choose casting if the part is large or hollow with complex internal geometry, will run in high volume so tooling amortises, and near-net material saving matters more than as-cast tolerance.
- Choose hybrid (cast blank, machined features) if the shape needs casting but the datums, sealing faces, or threads must hold a tolerance — very common, and the machining cost is then on the interfaces only.
- Still unsure. send the model; the right answer is usually visible from the geometry and the volume alone.
Where the two are combined
A cast near-net blank machined on its interfaces is the standard answer for a complex, tolerance-critical part: casting buys the shape, machining buys the fit. The cast blank should be stabilised (stress-relieved) before machining so it does not move after the datums are cut. Where the part can be cut from solid cleanly, cutting it is simpler and cheaper than casting and machining.
What tolerance applies, and what it costs
Milling and turning hold ±0.003 mm (milling) / ±0.002 mm (turning); precision grinding and wire EDM hold ±0.002 mm. Those are process capabilities, not defaults. a drawing does not need every dimension at the limit, and specifying tighter than the function requires is the single most common driver of unnecessary cost. Mark the features that matter and leave the rest to a general tolerance.
Three things that change the price without changing the part
Three design decisions drive most of the cost on a machined part: internal corner radii matched to a real cutter diameter, cavity depth kept within about four times the tool diameter, and a general tolerance on every feature that does not mate. Each one changes the tool that can be used, and the tool determines how much material can be removed per minute. Raise these at quote stage rather than after the first article.
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. The spare capacity in that family is what lets a part shift lanes instead of waiting in a 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 shop builds to the design you supply, 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 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.
Not sure this is the right process?
Send the model and the drawing and get a straight answer on whether machining, casting, or a cast-and-machine hybrid is the right route, including where a design change would cut cost. Reach Felipe Iglesias at [email protected] or +86 13126536955.
Frequently Asked Questions
Is inspection documentation included in the quote?
It should be stated explicitly. A first-article report is a document someone has to produce, and whether it is a full dimensional report or a sample plan changes both the cost and what you receive.
How are parts packed for export?
Packing is chosen per part — finished faces bagged and boxed, steel corrosion-protected. Include it in the quote, since it changes the cost and how the parts arrive.
Is 3D printing cheaper than CNC machining?
At quantity one, sometimes. Above the crossover quantity — which depends on size, material, and tolerance — machining is cheaper, and the gap widens with volume. A printed part that needs its interfaces machined carries both costs.
Can I audit the factory before placing an order?
Yes — on-site and video audits are both welcome at No. 8, Shuibian Songyuan Road, Hengli Town, Dongguan, Guangdong, China 523470.
Do you sign NDAs before reviewing drawings?
Yes — an NDA can be signed before any files change hands, and drawings stay inside the quoting system rather than circulating by email.
Can a printed part be machined afterwards?
Yes, and it frequently is. Sealing faces, bearing seats, and threaded features are machined on castings as a matter of course when they must hold a tolerance or a fit. The cast blank should be stress-relieved before machining so it does not move.
What is the difference between a prototype build and a production build here?
Usually only quantity and scheduling. Both run on the same machines and the same process, which is what makes a later ramp a scheduling change rather than a re-qualification.
Is casting cheaper than CNC machining?
In short, Only above the volume where its tooling amortises. Below that point machining is cheaper because it carries little fixed cost; above it, casting's lower per-part cost wins.
Which route gives certifiable material properties?
In short, Machining from certified wrought stock gives properties traceable to a mill heat or batch. A casting's properties depend on solidification and typically require NDT control for critical parts, so for a certified-material requirement machining is usually the simpler answer.
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 B209/B209M-21 — Standard Specification for Aluminum-Alloy Sheet and Plate
- ISO 9001 — Quality management systems — Requirements