Micro CNC machining lead times are quoted in tiers of roughly 3, 7, or 30 days, and on a micro part the tier is set by two things: the routing of the process steps and the metrology that the GD&T on the drawing demands. A simple part with few features and a loose geometric story runs fast; a micro part carrying tight position, cylindricity, and fit callouts against a datum structure runs long, because every geometric control is a measurement as well as a machining requirement. This guide walks the tiers, the callouts that own the schedule, and the ordering practices that keep a micro part date honest.
Why is a micro part lead time quoted as a tier rather than a date?
A meaningful date has to be built from the work, and on a micro part the work includes the measurement plan. A three-day part is simple — a few operations in a standard material with a handful of callouts and a routine inspection. A seven-day part is the typical order: more features, more operations, standard geometric controls, maybe a light finish. A thirty-day part is the complex route — many operations, a dense datum structure, tight position and form callouts, finishing or heat treatment, and a CMM program that takes real time to build and run.
The tiered quote is the honest form of a lead time because it names the workload behind the date, machining and metrology included. A shop that quotes one flat lead time for every micro part has not counted the steps or read the GD&T; one that quotes a tier with the routing explained has. The DFM review at quoting is where the steps are counted and the tier is set, which is why the review comes before the date, and on a micro part, the review should read the geometric controls as carefully as the dimensions.
Why do GD&T callouts drive the date on a micro part?
Each geometric control on a micro part is both a process requirement and a measurement requirement, and the measurement is often the harder of the two. A position tolerance against a datum needs a CMM run that builds its coordinate system from that datum; a cylindricity callout needs a roundness measurement along the feature; a concentricity between small diameters needs the metrology to resolve features measured in fractions of a millimetre. On a micro part the features are small enough that probing them reliably takes real time, and the inspection plan is part of the schedule.
The number of geometric callouts therefore decides how long the inspection owns the route. A drawing with a short list of key characteristics — a position on the mounting bore, a cylindricity on a journal — inspects quickly. A drawing with many tight geometric controls against several datums inspects slowly, because each control is a separate measurement against its frame, and each measurement has to be planned, run, and reported. When you ask what moves your part to a faster tier, the answer is often the datum structure and the count of geometric controls — simplifying them is the honest way to shorten the schedule.
Micro geometry adds its own schedule weight. Features measured in fractions of a millimetre need small tooling, careful feeds, and often more than one pass, and a micro hole or a thin web machined with the wrong strategy deflects or burns rather than cutting clean. The routing on a micro part is therefore not just a list of operations — it is a sequence built around the small features, and a sequence planned for those features holds tolerance the first time, while one that is improvised sends parts back to the machine for rework. Ask how the shop sequences the small features and which tools it plans to run; the answer separates a routing that was designed for the part from one that was simply applied to it.
Which step usually owns the schedule for a micro part?
For most micro parts the machining itself is not the bottleneck — the steps around it are. Material procurement owns the schedule when the stock is special-order or must arrive certified, because a micro part cannot start until its material is on the floor. Finishing owns it when the process runs at a specialist with its own queue. And the CMM metrology owns it on drawings with many geometric callouts, where the inspection is real time and a finding sends the part back to the machine.
your controls follow the owner. For material, ask at quoting whether the stock is in hand and, if not, what the procurement time is. For finishing, ask whether it is in-house or at a processor. For metrology, confirm which geometric controls carry measured values and whether the inspection plan is ready to run when the parts are — a CMM program that has to be written after the parts are machined adds days to the schedule. When the supplier names the owner of your date, it is running schedule discipline; a date quoted without an owner has not been counted.
How do process steps and material availability drive the date?
Each process step adds setup, run, and inspection time, and on a micro part the count of steps is the honest driver of the date. A simple micro part runs in a handful of operations; a complex one can carry many more, adding cross-features, secondary processes, and the measurements between them. The table below maps the common characteristics to the tier they usually land in.
| Part characteristic | Typical tier | What owns the schedule |
|---|---|---|
| Simple part, standard material, few callouts | About 3 days | A short routing and a quick inspection |
| Moderate features and geometric controls | About 7 days | More operations and standard CMM work |
| Dense datum structure, tight position and form | Toward 30 days | Sequencing plus real metrology time |
| Surface finishing or heat treatment in the route | 30-day tier | Processor queues and post-treatment work |
| Special-order or exotic material | 30 days or longer | Material procurement ahead of machining |
Material availability sits at the front of any schedule, because a micro part cannot start until its stock is on the floor. Standard alloys are in stock at most shops and start the moment the program is approved; a special-order alloy or a non-standard size moves procurement onto the critical path. Ask at quoting whether the material is in hand — the answer separates a start-now schedule from one that waits on a supplier, and on a micro part the same question applies to the small tooling and inserts the features demand.
How do quantity and release patterns interact with the tier?
For micro parts, the routing usually owns the schedule more than the count. A single part and a short run of the same geometry share a tier, because the process steps and the inspection plan are the same, and the extra parts add machine time that a shop schedules in blocks rather than day by day. The quantity only starts to move the date beyond a threshold, where the run occupies a machine for a measurable stretch. That is why you can validate a micro part on one piece and scale to a short run without restarting the lead-time clock from zero.
Beyond the threshold, the release pattern decides the schedule. A release that covers several weeks of consumption runs once, pays the setup once, and carries one lead time, while the same volume split into small releases restarts the setup and the tier on every batch. For a micro part in steady demand, consolidate the releases to the quantity your consumption supports, and share the forecast so the shop can plan the machines and the material around the program. If you order in isolation, you get the tail of the queue; if you share the program's shape, you get a schedule built around it.
What do drawing changes and quality gates do to the schedule?
A micro part schedule is built around a frozen drawing, and every change resets part of the clock. A revision that moves a feature or changes a datum means a program edit, a new first article, and usually a fresh CMM program, because the coordinate system of the measurement follows the geometry. Batch your changes into one release, ask what a revision does to the date before you send it, and treat the drawing as a controlled document — the design that stops changing is the fastest design there is.
Quality gates sit inside the schedule and are worth planning around. The first-article inspection on a new micro part, the CMM run on the geometric controls, and the material certificate check are the steps that keep a fast part from becoming a rejected one. Ask when the first article will be measured and reported, that date is the real proof point of the schedule. A shop that schedules the quality gates as part of the routing is running a schedule you can trust; one that treats inspection as spare time is promising dates it cannot hold.
How do you compress a micro part lead time without hurting quality?
Compression comes from removing steps and simplifying the measurement plan, not from rushing either. Run the DFM review with the schedule in view — every operation that a small design change eliminates is schedule recovered, and every geometric control that the function does not need is metrology time recovered. Approve the material and the finish at quoting so no decision waits on a later email, confirm the inspection plan so the CMM program is ready when the parts are, and tell the shop which date matters so it can plan the capacity around it.
Then use the drawing discipline that micro parts reward. A datum structure that is simple and unambiguous lets the metrology run once against a clear frame; a structure that buries features under stacked datums multiplies the measurement work. When a date is truly critical, say so early and ask what the fastest honest route is, not a rush on the process, but a routing and an inspection plan that reach the same result in fewer steps. The compression that happens at quoting is the only kind that is free, and the measurement plan that is ready on day one is the only kind that holds.
One more planning number belongs in the schedule: the buffer for first-article iteration on a new micro part. The first article is where a geometric control that the process cannot quite hold surfaces, and the fix — a fixture adjustment, a different finishing pass, a datum strategy change — takes time and may require a re-run. Plan for that iteration on a first order by adding a short margin to the internal target, because a new micro part with tight GD&T rarely passes first time with zero adjustment. A program that budgets for the first-article finding keeps its schedule; one that plans to the exact quoted day is surprised by it, and on a micro part the surprise usually lands on the CMM.
How do you plan a micro part program from prototype to repeat?
Lead time has to be planned at every stage of a micro part program. Prototype on a single part while the design is unproven, because a design error costs one part and the first article sets the process and the inspection plan. Move to a short validation batch once the drawing is stable, and use its report to lock the routing, the CMM program, and the documentation format. Then scale at the quantity your demand supports, with the first-article package as the baseline every repeat lot is measured against.
Plan backward from the need date at every stage: the machining tier, plus freight, plus receiving inspection, plus the buffer. Work the calendar back from the assembly or launch date and the placement date appears. The services page on this site explains how micro machining, finishing, and CMM inspection are combined into a route, and the GD&T FAQ covers how tolerances, fits, and geometric controls are verified in practice.
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). Chosen 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). Chosen 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). Chosen 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). Chosen for shafts, bushings, flanges up to ±0.002 mm.
- Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Chosen 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.
Have a micro part you want a date for — with the routing explained?
Email [email protected] or call +86 13126536955 and ask for the tier, the routing and inspection plan behind it, and what would move your part to a faster one.
Frequently Asked Questions
What is a realistic lead time for a micro CNC machined part?
Roughly 3, 7, or 30 days, set by part complexity, GD&T callouts, and process steps. Simple parts run about 3 days, standard parts about 7, and complex parts about 30. The tier follows the routing and the metrology the drawing demands.
Why do GD&T callouts affect the delivery date?
In short, Each geometric control is a process requirement and a measurement. A position tolerance needs a CMM run in its datum frame; a cylindricity callout needs roundness measurement.
Which step usually owns my micro part's schedule?
In short, Ask which operation is on the critical path. It is usually material procurement when the stock is special-order, a finishing step with its own queue, or the CMM metrology on a drawing with many geometric callouts.
Does a bigger order take longer than a small one?
In short, Up to a threshold, no — the tier is set by the process steps and the inspection plan, so the first piece and a production run share a tier. Beyond that threshold the quantity does move the date, which is why repeat volume is planned on its own schedule.
How do I get a shorter lead time without hurting quality?
In short, Compress the schedule by removing steps and simplifying the measurement plan. A design that machines in fewer operations ships faster; a datum structure that reduces geometric controls inspects faster.
How much buffer should I add beyond the quoted tier?
Add the freight transit to the machining tier for the delivery date, then a short buffer for the assumptions that can slip. The tier is machining days, not door-to-door days. A buffer absorbs the first slip without turning it into a crisis.
What should I send to get a fast, accurate date?
The complete package in one message — the drawing at a final revision with its datum structure, the material with its condition, the GD&T callouts, the quantity, and the target date. The fewer questions the shop must ask, the sooner the tier is set.
Standards referenced on this page
- ASTM A582/A582M-12 — Standard Specification for Free-Machining Stainless Steel Bars
- ISO 9001 — Quality management systems — Requirements
- ASTM E8/E8M-21 — Standard Test Methods for Tension Testing of Metallic Materials