CNC Lathe Machining Services

Which machining services run in-house, and pass audit?

Every service runs on our own floor, so the audit covers the actual work, not a brokered-out operation.

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

How do you audit the milling service?

Ask for a CMM report from a real milling job and the machine list. Milling holds ±0.003 mm and is verified on Hexagon CMMs — the evidence is in the report, not the brochure.

The audit question behind the report is which features were measured and against what. A real CMM report names the part, the characteristic, and the measured value; a capability statement says "we hold ±0.002 mm (turning) / ±0.003 mm (milling)" and proves nothing. Ask for a report where the tolerances on your drawing class of part — a housing, a bracket, a prismatic part — are the ones measured. The number of axes matters too: a 5-axis part has features a 3-axis center cannot reach in one setup, so ask whether the part ran on one machine or moved between several.

How do you audit the turning service?

Ask for an SPC chart from a real turning run. Turning holds ±0.002 mm up to Ø720 × 1280 mm, and the control chart shows the process stayed capable across the run.

The chart is the turning service's real resume, because turning is where runout and concentricity live. A turned diameter can be in size on every section and still be off-axis, so the audit asks for the control that catches the axis error — the SPC chart on the critical diameter, with the Cpk and the run length, not a single first-piece measurement. Ask which feature drove the Cpk and how long the run was; a capable process is proven over consecutive parts, not over one.

How do you audit mill-turn and grinding?

Ask what relationship tolerances the mill-turn held, and what surface finish the grinding achieved. Both are documented — the record is the audit evidence.

Mill-turn is audited on relationship tolerances because that is what single-setup machining buys: a bore square to a face, a cross-hole on the axis of a shaft, features that share one datum because they were cut in one clamp. Ask for the CMM report on that relationship, and the routing should show one machine, not two. Grinding is audited on finish and roundness: a sealing diameter should carry an Ra number and a roundness trace, because a grinder that holds size but not finish is only half the service. Both records exist on the floor, and both should be handed over without hesitation.

How do you audit the quality system?

Ask for the certificate numbers and verify them with the registrar, and ask to see the inspection bench. A real system produces both without hesitation.

The certificate number is the verifiable half of the claim. ISO 9001:2015 (116024/A/0001/UK/En) covers the machining of metal parts; IATF 16949:2016 (131941/A/0001/SM/En) covers manufacture, with product design excluded under Clause 8.3; ISO 14001:2015 (116024/B/0001/UK/En) covers the environmental side. Verify the numbers with the registrar, and the scope with the supplier — a build-to-print shop says so, and that honesty is itself an audit signal.

What does a supplier audit visit cover?

A visit covers the machine floor, the inspection bench, and the people. You reconcile the machine list against the floor, see the CMMs run, and meet the team — the strongest audit there is.

Which secondary operations can be audited?

• 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.

The audit point on secondary operations is ownership, not capability. Finishing and heat treatment each need a named owner — in-house or a named partner — because a coating thickness that shifts a tight diameter is a defect as real as a size miss. Ask who owns the anodize line and who owns the oven, and the answer should be specific. A shop that bundles finishing under one vague "surface treatment" line has not thought through who is accountable for the final micron.

When hard turning replaces a grind operation

Not every tight turned diameter needs grinding. Hard turning on a rigid lathe can hold a few microns on a through diameter and removes a handling step and a grinder queue. We use it when the feature is a simple revolved diameter and the material is already hardened, and we keep cylindrical or centerless grinding for the ±0.002 mm band, for shoulders and faces hard turning cannot reach, and for through-hardened parts that load the tool. The call is on the drawing: if you mark a diameter at ±0.002 mm we route it to a grinder; at ±0.002 mm we review whether hard turning will hold Cpk ≥ 1.67 on your volume. Stating the real need saves the grind cost where it is not earned.

What does the tolerance band buy you in turning?

The tolerance you call out is the main cost lever on a turned part, and the step from one band to the next is not linear. A diameter at a general tolerance cuts fast on a standard lathe with a normal setup. The same diameter at ±0.002 mm adds a dressed collet, a tuned finishing pass, and an SPC chart to prove the band held. At ±0.002 mm the part routes to a grinder, which is a separate machine, a separate setup, and a separate queue. None of this is hidden cost; it is cost that follows the print. The buyer decision is to mark tight only the features the assembly actually loads, and to say so on the drawing so the quote routes each diameter to the cheapest process that still holds it.

Tolerance band	Process	What you are paying for
General / open	Standard turning	Fast cutting, one setup
±0.002 mm	Turning with SPC evidence	Dressed collet, finishing pass, control chart
±0.002 mm	Cylindrical / centerless grinding	Separate machine, setup, and queue

How do you question a machining service, not just its brochure?

• Ask for one CMM report from a real job. The report names the part, the characteristic, and the measured value; a brochure does not.
• Ask which feature drove the Cpk, and what the chart length was. A capable process is shown over a run, not over one piece.
• Ask whether mill-turn or two separate machines will make the part. The answer tells you how much handling and re-clamping risk your tolerances carry.
• Ask who owns the secondary operations. Finishing and heat treatment should have a named in-house or partner owner.

How does material choice change the service routing?

Material is the hidden variable in any machining service quote, because the same geometry costs differently in different alloys. Aluminum cuts fast and clears chips easily, so a housing in 6061-T6 is a quick milling job. A stainless part with the same features runs slower, wears inserts faster, and needs controlled feed to avoid work-hardening, so the same drawing is a longer cycle. Titanium springs back and holds heat in the cut, which forces light passes and an allowance for a finishing cut. The routing — speeds, feeds, tooling, and the number of passes — changes with the material, and so does the price.

For you this means the material should be named on the RFQ, not left as "metal." A quote on 6061-T6 and a quote on 17-4 PH are not comparable until both state the alloy, because the machining hours differ. The supplier that asks which alloy before quoting is estimating the part; the one that quotes a single number without asking is guessing.

What relationship tolerances does mill-turn protect?

Mill-turn earns its place on the parts where two features must share an axis or a face, because single-setup machining cuts them in one clamp. The classic cases are a bore that must be square to a face, a cross-hole that must sit on a shaft's axis, and a turned profile that must align with a milled flat. On a lathe-and-mill handoff, each of those features is located twice, and the second location carries an error nobody measured. On a mill-turn center, both features hang off one datum, so the relationship is cut, not re-established.

The audit question is whether the routing says one machine or two. A quote that routes a bore and its mating face through mill-turn is protecting the relationship; a quote that splits them across a lathe and a mill is accepting the re-clamping error and hoping the tolerance absorbs it. When the relationship is tight, the service should be mill-turn, and the routing should say so in writing.

What DFM flags should a service quote raise?

A machining service quote is also a design review, and the best quotes raise the design's problems before they become your parts. The flags to watch for: a square shoulder with a tight diameter and no relief groove, a wall too thin to hold a tight turned feature, a datum that is a theoretical axis instead of a grippable surface, and a runout callout on a feature the assembly does not actually load. Each of those is a cost or a quality risk the print introduced, and a supplier that names them is reading the drawing.

The supplier that quotes the drawing silent — no questions, no flags — is either not reading it or deferring the problem to the first article. The DFM flag is not a sales tactic; it is the moment the machining service shows its engineering, and it is the cheapest time to fix a drawing. Insist on a DFM note in the quote, and you get the design problems surfaced before they are machined into metal.

Which machining services does a turned-part program actually need?

Most turned-part programs are not one service; they are a routing across several, and the routing is the decision you are really making. A simple pin needs only turning. A shaft with a bearing seat needs turning plus a grind on the seat. A flange with a bore and bolt holes needs mill-turn. A part that starts as a casting or a near-net blank needs milling to finish it. The service list is the answer to "how does this part get from stock to finished," and a supplier that can show the routing is showing you its cost structure.

Part	Routing	Critical evidence
Simple turned pin	Turning	SPC chart on the diameter
Shaft with bearing seat	Turning + cylindrical / centerless grind	Roundness trace + Ra on the seat
Flange with bore and holes	Mill-turn, single setup	CMM report on bore-to-face squareness
Near-net blank	Milling to finish	CMM report on critical features

The routing is also where the tolerance ladder shows up: the turning holds ±0.002 mm, the grind takes the seat to ±0.002 mm, and each step is a line item with its own evidence. A supplier that can show the routing with the evidence per step is a supplier you can audit; one that offers "machining" as a single opaque service is not.

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 B348/B348M-21 — Standard Specification for Titanium and Titanium Alloy Bars and Billets
• ISO 9001 — Quality management systems — Requirements