CNC Lathe Machining Parts

What types of machined parts can you produce, and prove?

The floor covers the full metal-cutting range, and the evidence trail follows every part. The proof question is not "can you make this part" but "can you show the measurement on this part," and every process below has a report behind it — a CMM dimension, an SPC chart, or a material certificate.

Process	Capacity	Max workpiece
3-axis milling	50+ centers	1300 × 700 × 600 mm (milling)
4-axis milling	20+ centers
5-axis milling	20+ centers
CNC turning	25+ lathes	Ø720 × 1280 mm
Mill-turn	Multi-task centers (Mazak / Brother class)	Single-setup complex geometry
Grinding	7+ (surface / centerless / cylindrical)	±0.002 mm finishes

Which materials can you machine, and verify?

Material family	Grades we run	Notes for buyers
Aluminum	6061, 6063, 6082, 7075, 2014	Fastest to machine; the default for prototypes and production
Stainless steel	303, 304, 316, 316L, 17-4PH	303 for free-machining; 316L for corrosion; 17-4PH for strength + aging
Carbon / alloy steel	1018, 1045, 4140, 4340, 12L14	Carburizing or nitriding available for wear parts
Brass / copper	C360, H62, C110	For electrical and thermal conductivity
Titanium	TA2, TC4 (Grade 2 / 5)	Stress-relief above 500 °C is outsourced to a qualified partner
Plastics	ABS, POM, nylon, PTFE, PEEK	For insulators, non-metal prototypes, and low-friction parts

Every incoming lot is XRF-checked against its mill certificate, so the material claim is verifiable, not verbal.

The material list is also a cost and quality signal for turned parts specifically. 303 stainless is the free-machining choice when a turned pin needs corrosion resistance without the slow cycle of 304; 17-4 PH is machined in the solution-treated state and then aged for strength. Titanium Grade 5 springs back, so a thin wall needs a light finishing pass and allowance left for it. The alloy you name on the drawing is the alloy the XRF confirms at the dock, and the two must match, or the part is wrong before the first cut.

What tolerances can you hold — with evidence?

Process	Held tolerance	Typical use
CNC milling	±0.003 mm	Housings, brackets, prismatic parts
CNC turning	±0.002 mm	Shafts, pins, bushings, round parts
Precision grinding	±0.002 mm	Bearing seats, roundness-critical surfaces

We hold these to process capability, demonstrated by SPC with Cpk = 1.851 (one characteristic on one part, not a blanket capability claim) on a representative length characteristic.

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.

A tolerance number without a capability number is a hope. ±0.002 mm (turning) / ±0.003 mm (milling) means something only when the process is shown to sit comfortably inside that band across a run, and Cpk = 1.851 (one characteristic on one part, not a blanket capability claim) on a representative length characteristic is that proof. The tolerance ladder — general, ±0.002 mm (turning) / ±0.003 mm (milling), then ±0.002 mm — maps to the routing ladder: standard turning, turning with SPC evidence, then a grind step. Each step is a line item, and each line item has its own evidence.

How are parts verified before they ship?

• 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.

What audit evidence ships with parts?

• Material certificates, with XRF verification.
• CMM dimensional reports for critical dimensions.
• SPC control charts for process-critical characteristics.

The three documents are what turn a box of parts into a verifiable shipment. The material certificate proves the alloy; the CMM report proves the dimensions; the SPC chart proves the process stayed capable across the run. For a turned part the CMM report should name the control that was actually verified — concentricity, runout, or true position — so the evidence matches the callout on the print. A supplier that ships parts with no documentation is asking you to take the tolerance on faith.

Which secondary operations are auditable?

• Surface finishing: standard and hard anodizing, zinc / nickel / silver / gold / chrome plating, powder coating, painting, brushing, mirror polishing.
• Heat treatment: vacuum, bright, carburizing, nitriding, and stress-relief aging. In-house ovens reach 500 °C (fine for aluminum and low-temperature steel stress relief); titanium stress relief above that is outsourced to a qualified partner.
• Deburring, tapping, laser marking, assembly: included as your print requires.

Secondary operations are where the parts supplier's honesty shows, because each one is either in-house or a named partner, and the difference is auditable. A coating thickness that shifts a tight bore or a heat-treat step that distorts a slender shaft is a defect as real as a size miss. Ask who owns each operation, and the answer should be specific, not a vague "we handle finishing." The ownership is part of the routing, and the routing is part of the evidence.

What should you check before ordering parts?

Which turned parts fail first on concentricity?

Round parts do not fail evenly. A shaft with a bearing seat at each end carries more risk than a simple pin, because two features must share one axis and any offset loads one bearing harder than the other. A long, thin pin or bushing is lower risk until the part deflects under the tool and the axis wanders with it. Judge by the ratio of length to diameter, not by part name: the longer the unsupported span, the more of the runout budget shifts from spindle to tool deflection. If you ask which feature is the datum, and what runout the drawing actually needs, you get a routing that holds concentricity where it matters instead of paying for it everywhere.

Part type	Typical critical feature	Control that matters
Shaft with two bearing seats	Coaxiality of both seats	True position to datum A, Cpk ≥ 1.67 on the runout
Long, thin pin / bushing	Straightness and roundness	Short tool overhang, light finishing pass
Flange / housing bore	Bore-to-face squareness	Single-setup mill-turn, one clamp for both features
Hardened sealing diameter	Roundness and finish	Routed to grinding for the ±0.002 mm band

What questions expose a parts supplier before you order?

• Which feature is the datum, and what does the drawing actually need? A shop that answers in engineering terms is reading your print; one that repeats a headline tolerance is not.
• Show the SPC chart for the feature you call critical. A real chart has a run length and a Cpk, not a single measurement from the first piece.
• Which operation is in-house and which is outsourced? Anodizing, heat treatment, and grinding each need a named owner, in-house or a named partner.
• How do you verify the material is the grade on my drawing? The answer should name the XRF check against the mill certificate, not a promise.

How does part geometry change the machining cost?

The geometry is the cost, and the cost shows up in the routing before the price. A simple prismatic part runs on a 3-axis mill in one setup; a part with features on multiple faces needs a 4- or 5-axis center or several re-clamps, and every re-clamp adds a locating error and a handling step. A turned part with a single diameter is one pass; a shaft with steps, threads, and a sealing seat is a routing of turning, threading, and grinding.

your lever is design-for-manufacturing. A bore that can be reached from one side, a shoulder with a relief groove, a wall thick enough not to deflect — each of those choices is the difference between a fast routing and a slow one. The supplier's DFM review surfaces these before the quote, and a part that arrives with DFM notes is cheaper to make than the same part quoted blind.

What makes a turned part a grind job instead of a turn job?

The call between turning and grinding is made on three things: the tolerance, the material, and the geometry. A diameter at ±0.002 mm is a turning job; at ±0.002 mm it routes to a grinder. A hardened part — through-hardened to around 60 HRC — is ground after heat treatment because cutting it in the hard state loads the tool. A sealing diameter that needs both a tight size and an Ra 0.8 µm finish is ground for both in one operation.

The decision is also about shoulders and faces. A through diameter is a centerless-grind job; a shoulder or a face is cylindrical grinding; a flat reference is surface grinding. Hard turning on a rigid lathe can hold a few microns on a simple revolved diameter and removes a handling step, but it cannot reach what a grinder can. State the real need on the drawing and the routing lands on the cheapest process that still holds it.

Which turned parts fail first, and how do you prevent it?

Round parts fail on concentricity when two features must share an axis and one of them is off. A shaft with a bearing seat at each end is the classic: if the two seats are not coaxial, one bearing loads harder than the other and wears early. A long, slender pin fails on deflection, because the part bends under the tool and the axis wanders. A flange with a bore fails on bore-to-face squareness, because the face that locates the mating part must be square to the bore it centers.

Prevention is a drawing discipline, not a machining trick. Name the datum, number the critical feature, and let the routing follow the load — a grind step on the sealing seat, a center on the long shaft, mill-turn for the bore and face in one clamp. The parts that fail are the ones where the print left the critical control unspecified and the shop guessed. A print that says what the assembly needs is a print that comes back right the first time.

How do you audit a parts supplier you cannot visit?

When a visit is not practical, the audit runs on documents, and the documents are the same ones a visit would verify. Ask for the registration number and check it against a public registry; ask for the machine list and read it for models and counts; ask for a CMM report from a real job and an SPC chart with a run length; ask for the certificate numbers and verify them with the registrar. A manufacturer produces all four in writing; a middleman hedges on at least one.

The remote audit is slower than a walk but it works, because a trading desk cannot fabricate a measured report or a verifiable certificate on demand. For this floor the answers are Dongguan Zhuohang Ltd, registration 91441900MA4UWT6X39, the machine list behind 100+ machines, CMM and SPC evidence from real runs, and 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). Email [email protected] and the documents arrive in writing.

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). 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: ±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.

Frequently Asked Questions

Standards referenced on this page

• ASTM B211/B211M-19 — Standard Specification for Aluminum-Alloy Rolled or Cold Finished Bar, Rod, and Wire
• ASTM A276/A276M-17 — Standard Specification for Stainless Steel Bars and Shapes
• ISO 9001 — Quality management systems — Requirements