Stainless Steel CNC Precision Machining

The design levers on stainless are wall thickness and pocket depth. Thin walls distort as roughing releases residual stress, so a stress-relief operation and a separate finishing pass are usually cheaper than trying to hold a thin wall in one go. Avoiding a dwell, a tool rubbing rather than cutting. Matters more here than on any other common material.

This belongs in the quote discussion, not the first-article review, because the changes are usually trivial on the drawing and significant on the machine.

Which entity is responsible for the work?

Dongguan Zhuohang Ltd (Registration No. 91441900MA4UWT6X39, established 2005).

What is on the floor, by machine family?

Capacity is depth, not a headline machine. The table below is the routing map: each family has a lane, and the depth in each lane is what keeps a part out of someone else's queue.

Machine family	Count	Representative models	Role in the schedule
3-axis vertical machining	50+ centres	Brother SPEEDIO S500Z2N / S700Z2N	Prismatic work at the lowest cost per part
4-axis machining	20+ centres	Mazak VCE-430AL / VCE-570CL	Indexed multi-face parts without re-fixturing
5-axis machining	20+ centres	Mazak VARIAXIS i series	Single-setup complex geometry
5-axis mill-turn	—	Mazak INTEGREX i-H series	Turned and milled features in one clamping
CNC turning / mill-turn	25+ lathes	Mazak QT-COMPACT 200MSY L	Round parts, live tooling
Swiss-type turning	—	Citizen Cincom A20 / Star SR-32JII / Tsugami B0205	Long, slender parts at high L/D ratios
Precision grinding	7+ grinders	—	Final tolerance on bearing seats and roundness-critical faces
Wire EDM	—	Sodick	Sharp internal corners and hardened material

What to read out of this list: a part does not wait behind a single machine. Depth in the same family is what lets work move to another lane rather than sit in a queue, and it is what makes a prototype ramp to production on the same floor.

Grade selection for stainless steel

Austenitic, martensitic, and precipitation-hardening stainless grades are the grades that come up in practice. 303 for free-machining work, 304 and 316L for corrosion resistance, 17-4 PH where strength is needed after ageing, 416 and 420 where hardness is required.

Your grade selection is usually settled by the service environment, corrosion, strength, or temperature, and only then by machinability. If you choose on machinability first, your part meets the drawing and fails in service.

How stainless steel moves after the cut

Dimensional stability is good once the part has stopped moving, but thin walls distort from the residual stress released by removing stock. Stress-relieving between roughing and finishing is the standard response on a tight-tolerance thin-wall part.

The general rule for your part is that 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.

What is the certification position?

ISO 9001:2015, IATF 16949:2016 (excluding clause 8.3 product design), and ISO 14001:2015 — each with a certificate number verifiable with the registrar.

Ppk and Cpk, with the stage named

For capability reporting, key and special characteristics start at Ppk ≥ 1.67 and run at Cpk ≥ 1.33 in production; general characteristics start at Ppk ≥ 1.33. Results are always quoted with the index, the stage, and the sigma estimator named, because VDA and AIAG use the same index names for opposite periods and quoting "Cpk 1.67" without that context is meaningless.

Values between 1.33 and 1.67 are conditional acceptance requiring customer review. Not a pass. Stating that boundary is deliberate: a supplier that reports a number without its stage and its estimator has not told you whether the process was stable when it was measured.

Stainless steel CNC precision — the alloy selection matrix

Stainless steel is the workhorse of CNC precision, and the alloy selection runs on four classes: austenitic (300-series, non-magnetic, corrosion-resistant, food and medical), martensitic (400-series, magnetic, hardenable, cutlery and surgical), precipitation-hardening (17-4PH / 15-5PH, high-strength, aerospace and defense), duplex (2205, higher strength plus corrosion, oil and gas). The tolerance: 303 (free-machining austenitic, 80 percent machinability) holds ±0.003 mm on milled, ±0.002 mm on turned, ±0.05 mm on general. 304 (50 percent machinability) holds 20 percent wider; 17-4PH (40 HRC) holds ±0.003 mm with ceramic inserts at low speed. The cost: 303 $6-10/kg; 304 $6-10; 17-4PH $12-20; 2205 $8-14. Application: 303 general; 304 food/medical; 316 marine/chemical; 17-4PH aerospace/defense; 2205 oil/gas.

The shop: Dongguan Zhuohang Ltd (USCC 91441900MA4UWT6X39, established 2005, 6,800 sqm floor, 100+ staff, 100+ machines, Mazak VARIAXIS I-600, INTEGREX I-250H S, TSUGAMI B0206-III, STAR SR-32J Type N, Citizen Cincom A20-3F7, Hexagon CMM with 10:1, 20 ±1 °C inspection room, ISO 9001:2015 116024/A/0001/UK/En, IATF 16949:2016 131941/A/0001/SM/En, ISO 14001:2015 116024/B/0001/UK/En). Tolerance: ±0.003 mm milling, ±0.002 mm turning, Ppk ≥1.67, Cpk ≥1.33. Contact: Felipe Iglesias, +86 13126536955, [email protected], PT/EN/FR/ES/ZH/JP.

Stainless steel surface treatment and passivation

Stainless steel CNC precision parts often need a surface treatment for corrosion resistance or cosmetic appearance. The treatments: (1) passivation (per ASTM A967, removes free iron from the surface, restores the chromium oxide passive layer — the standard for corrosion resistance on 300-series); (2) electropolishing (removes 5-15 µm, brightens, improves corrosion resistance — the standard for food and medical); (3) pickling (acid etch, removes scale and oxide — the standard after heat treatment); (4) bead blast (cosmetic, matte finish, Ra 1.6-3.2 µm); (5) mirror polish (cosmetic, Ra 0.05-0.2 µm, the standard for decorative). The dimensional change: passivation negligible (removes free iron, not base metal); electropolishing removes 5-15 µm (account for this on mating features); pickling removes 5-10 µm. You should specify the treatment on the RFQ; one that does not is one whose stainless ships bare.

The shop: Dongguan Zhuohang Ltd (USCC 91441900MA4UWT6X39, established 2005, 6,800 sqm floor, 100+ staff, 100+ machines, Mazak VARIAXIS I-600, INTEGREX I-250H S, TSUGAMI B0206-III, STAR SR-32J Type N, Citizen Cincom A20-3F7, Hexagon CMM with 10:1, 20 ±1 °C, ISO 9001:2015 116024/A/0001/UK/En, IATF 16949:2016 131941/A/0001/SM/En, ISO 14001:2015 116024/B/0001/UK/En). Tolerance: ±0.003 mm milling, ±0.002 mm turning, Ppk ≥1.67, Cpk ≥1.33. Contact: Felipe Iglesias, +86 13126536955, [email protected], PT/EN/FR/ES/ZH/JP.

Stainless steel surface treatment and passivation

Stainless steel CNC precision parts often need a surface treatment for corrosion resistance or cosmetic appearance. The treatments: (1) passivation (per ASTM A967, removes free iron from the surface, restores the chromium oxide passive layer — the standard for corrosion resistance on 300-series); (2) electropolishing (removes 5-15 µm, brightens, improves corrosion resistance — the standard for food and medical); (3) pickling (acid etch, removes scale and oxide — the standard after heat treatment); (4) bead blast (cosmetic, matte finish, Ra 1.6-3.2 µm); (5) mirror polish (cosmetic, Ra 0.05-0.2 µm, the standard for decorative). The dimensional change: passivation negligible; electropolishing removes 5-15 µm (account for this on mating features); pickling removes 5-10 µm.

The shop: Dongguan Zhuohang Ltd (USCC 91441900MA4UWT6X39, established 2005, 6,800 sqm, 100+ staff, 100+ machines, Mazak VARIAXIS I-600, INTEGREX I-250H S, TSUGAMI B0206-III, STAR SR-32J Type N, Citizen Cincom A20-3F7, Hexagon CMM 10:1, 20 ±1 °C, ISO 9001:2015 116024/A/0001/UK/En, IATF 16949:2016 131941/A/0001/SM/En, ISO 14001:2015 116024/B/0001/UK/En). Tolerance ±0.003 mm milling, ±0.002 mm turning, Ppk ≥1.67, Cpk ≥1.33. Felipe Iglesias +86 13126536955 [email protected] PT/EN/FR/ES/ZH/JP.

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). Intended 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). Intended 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). Intended 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). Intended for shafts, bushings, flanges up to ±0.002 mm.
• Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Intended 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 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.

Stainless Steel CNC Precision Machining — Related Pages

• prototype material selection types trade offs and how to choose
• sand casting for prototypes aluminum types trade offs and how to choose
• 3 axis cnc precision machining