3-axis milling
Three-axis milling covers most prismatic parts: plates, flanges, brackets, housings. It is the most economical process when the faces can be reached in one to three set-ups.
Expertise
CNC machining subcontracting
Milling, turning, 5-axis machining: describe your parts once and compare quotes from CNC machining workshops across Europe.
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Outsourcing your parts to a CNC machining workshop gives you access to machines, programmers and inspection equipment that would be costly to bring in-house. Whether it is a single turned shaft to get a line running again, an aluminium bracket in batches of twenty or a run of several thousand precision parts, machining subcontracting rests on the same logic: a material, a drawing, a quantity and a level of requirement.
Workshops fall into three broad families. Milling shops machine prismatic parts on 3, 4 or 5-axis machining centres; turning shops make round parts, from bar feed to chuck work; mixed workshops run mill-turn centres able to finish a complex part in a single clamping. Many complete their machine park with grinding, spark erosion (EDM) or deep-hole drilling.
This page helps you prepare a clear CNC machining quote request: available processes, common materials, realistic tolerances, the factors that drive price and the documents to attach. The more precise your request, the more comparable the quotes you receive, and the faster you find the workshop that really fits your need.
Common services
4 and 5-axis milling
A rotary table or tilting table lets you machine several faces in a single clamping (3+2 positioning) or follow free-form surfaces continuously, for complex one-piece parts.
CNC turning
Shafts, bushes, fittings, spacers: turning produces round parts, one at a time on a CNC lathe or in volume on a bar-fed sliding-head lathe.
Mill-turn
Turning centres fitted with driven tools and a Y axis produce flats, off-centre holes and tapped threads without changing machine, which improves concentricity and reduces handling.
Grinding
When the tolerance drops to a hundredth of a millimetre or the surface finish must be very fine, cylindrical or surface grinding finishes the part after heat treatment.
Spark erosion (EDM)
Wire EDM cuts precise profiles in hardened steels; die-sinking produces shapes a cutting tool cannot reach, such as sharp internal corners.
Deep-hole drilling
Gun drilling produces holes whose length is far more than ten times the diameter, useful for cooling circuits or cylinder bodies.
Materials worked
Aluminium (6061, 6082, 7075, 2017A, 5083)Structural and engineering steels (S235, S355, C45)Alloy steels for heat treatment (42CrMo4, 16MnCr5)Stainless steels (304L, 316L, 17-4PH)Brass, bronze and copperTitanium Ti-6Al-4V and nickel-based alloys (Inconel)Cast irons (EN-GJL, EN-GJS)Engineering plastics (POM-C, PA6, PEEK, PTFE, PE-UHMW)
Common applications
- Spare parts and emergency repairs for production machinery
- Functional prototypes and validation parts for design offices
- Tooling, jigs and inspection fixtures for the workshop
- Precision parts for aerospace, space and defence
- Components for medical devices and laboratory instruments
- Parts for special-purpose machines and automation
- Parts for automotive, motorsport and electric mobility
- Hydraulic, pneumatic and valve components
What affects the price
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1
Material and stock size
The cost of the material, the size of the raw stock (bar, plate, forging) and the chip removal rate weigh heavily: a part that removes 80% of a block costs more than one cut close to its final shape.
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2
Machine time
This is generally the biggest cost item. It depends on the number of operations, re-clampings and special tools, and on the type of machine used, as a 5-axis centre is charged at a higher hourly rate than a 3-axis one.
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3
Programming and set-up
CAM programming, the clamping fixture and the first validated part are fixed costs. Spread over a batch they weigh little; on a single part they explain the higher unit price.
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4
Tolerances and surface finishes
Every tight dimension may require finishing passes, dedicated inspection, even grinding. Reserving tight tolerances for functional dimensions is the simplest way to control cost.
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5
Quantity and repeat orders
A batch launched in one go, or a contract for repeat orders, lets the workshop optimise set-up and material purchasing, and therefore lower the unit price.
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6
Treatments, inspection and certificates
Heat or surface treatment, dimensional report, material certificate, special packaging: these additional services come on top of machining and should be requested from the outset.
Tips for a successful request
Post a request- Attach a 3D model in STEP format and a dimensioned PDF drawing: the first is used for programming, the second specifies tolerances, threads and surface finishes.
- State the exact material grade (for example 6082-T6 or 316L) rather than just “aluminium” or “stainless steel”.
- State the quantity for this order, but also the annual volumes you expect: this changes the machining strategy and the price.
- Mark the critical dimensions (fits, seal seats, H7 bores) and leave the general ISO 2768 tolerance for the rest.
- Mention post-machining treatments (anodising, hardening, zinc plating) and the inspection you expect, such as a dimensional report or a 3.1 material certificate.
- State the delivery date you want and say whether it is firm: a realistic lead time opens up more quotes.
Tolerances and surface finishes: what CNC machining can hold
Without specific instructions, most workshops apply the general tolerance of the ISO 2768 standard, often in the medium class “m”. This rule is enough for the vast majority of non-functional dimensions. For mating surfaces, you specify an ISO tolerance (H7 bore, g6 shaft) or a numerical value. Here are some usual benchmarks, given as a guide:
| Level of requirement | Order of magnitude | Usual means |
|---|---|---|
| General tolerances | ±0.1 to ±0.5 mm depending on the dimension (ISO 2768-m) | Standard milling and turning |
| Fitted dimensions | H7: a few hundredths of a millimetre, i.e. +0.021/0 mm for a 25 mm bore | Bore finished with a tool, careful finishing |
| High precision | ±0.01 mm or better on targeted dimensions | Grinding, temperature-controlled workshop, 3D measurement |
Surface finish follows the same logic. A roughness of Ra 3.2 µm is common straight off the machine; Ra 1.6 µm calls for careful finishing; below 0.8 µm you need specific passes, grinding or polishing. The lower you go, the higher the cost climbs: only require it on sealing, bearing or sliding surfaces.
Finally, think about the material itself. Aluminium expands, thin parts distort under cutting forces, and a heat or surface treatment changes dimensions. To go further, read our guide to machining tolerances and ISO 2768.
Milling, turning or mill-turn: which process for which part?
The right process depends first on geometry. A round part (shaft, bush, pulley) is turned; a prismatic part (plate, block, housing) is milled; a hybrid part, with a round form and cross holes or flats, is best made on a mill-turn centre, which avoids re-clamping and guarantees concentricity between surfaces.
The number of axes also affects quality. 5-axis machining in positioning mode lets you reach several faces without removing the part: the accumulated re-clamping errors disappear, but the machine hour is more expensive and programming takes longer. For a large run of small round parts, the bar-fed sliding-head lathe, often called screw machining, sharply cuts cycle time; this speciality is particularly established in France’s Arve Valley, in Haute-Savoie.
- One-offs or very small batches: favour a versatile, responsive workshop that accepts set-up for just a few parts.
- Repeat production runs: look for a workshop equipped with dedicated machines, automatic loading or quick-clamping systems.
- Very high-precision parts: check for a grinding machine, a measuring room and a track record in your sector.
After machining, the part often goes on to a surface treatment or a dimensional inspection. Ask the workshop how it organises these steps: a single coordinator simplifies logistics and responsibility.
Preparing your quote request and comparing offers
A complete file follows a simple order: the 3D model (STEP), the dimensioned PDF drawing with its tolerances, the material grade, the quantity, the treatments, the inspection requirements and the date you want. Add a sentence on what the part is used for: an experienced machinist will often spot a dimension to relax or a fillet to add that saves everyone time.
On Meaflow, you post this request for free as a project request. Interested workshops ask their questions by messaging, then send you their quotes; you view them side by side before choosing. For a first order, do not hesitate to ask for a few references close to your part.
When comparing, do not stop at the total price. Check what is included (material, deburring, inspection, packaging, transport), the tolerance assumptions used, the lead time quoted and how long the quote is valid. Our guide to the price of CNC machining explains how a quote is built, and the one on writing a subcontracting quote helps you ask the right questions. Ready to launch your project? Post your request.
Guides to go further
CNC machining prices: how is a quote calculated?
Programming, setup, cycle time, material, finishing, inspection: what a CNC machining quote contains, why quantity changes everything and how to reduce the cost.
Machining tolerances: ISO 2768, fits and dimensioning
ISO 2768 general tolerances, ISO 286 fits, ISO 1101 geometric tolerancing, Ra roughness: read a drawing and dimension sensibly to control the cost of a machined part.
Aluminium, stainless steel, steel, engineering plastics: choosing the right material for your parts
Aluminium 6082 or 7075, stainless 304L or 316L, POM or PA6: the criteria for choosing the right material, a comparison table and the effect of this choice on price and lead times.
Related expertise
Sheet metalwork & cutting
Laser, plasma and waterjet cutting, bending
Inspection & metrology
Dimensional inspection, NDT, reports
Surface treatment
Painting, powder coating, anodising, galvanising
Prototyping
Functional prototypes, pre-series, models
Frequently asked questions
A question not answered here? Visit the help centre or write to us.
How much does a CNC-machined part cost?
There is no price per kilo or single rate: the cost depends on the material, machine time, set-up, tolerances and quantity. A single part bears all the programming and set-up on its own, whereas in a batch these costs are spread. The most reliable approach is to compare several quotes based on the same complete file, with a dimensioned drawing and 3D model.
What is the lead time for machining a part?
As a guide, allow from a few days for a simple part in a common material to several weeks for a batch, a material that has to be sourced or an associated treatment. The lead time depends mostly on the workshop’s workload when you order. State your desired date in the request to receive realistic quotes.
Can I have just one part machined?
Yes, many workshops accept one-off parts, especially for maintenance and prototyping, even though the unit price is higher than in a batch. There is no common minimum quantity: each workshop sets its own terms. Simply say it is a single part, and say whether a batch could follow.
Which files should I provide for a machining quote?
Ideally provide a 3D model in STEP format and a dimensioned PDF drawing stating the tolerances, threads, surface finishes, material and treatments. Without a 3D model, a complete, legible 2D drawing is often enough. If you only have a sketch or a sample part, say so: some workshops offer a dimension survey.
What tolerance can be achieved in CNC machining?
In standard machining, ±0.1 mm is held without particular difficulty and corresponds to the ISO 2768-m general tolerances on small dimensions. On targeted dimensions, a careful workshop can get down to a few hundredths of a millimetre. Beyond that you need grinding, 3D measurement and sometimes a temperature-controlled workshop: the price rises accordingly.
Can the workshop supply a material certificate and an inspection report?
Yes, provided you ask for it at the quote stage. A type 3.1 material certificate under the EN 10204 standard and a dimensional report are common services, charged extra. State the number of parts to inspect (first article, sampling or all of them) so that every workshop quotes the same thing.
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