CNC Machined Part

CNC Machining

Ideal for prototypes and low volume production parts (1 to 40+).

Request an online quote today.


ISO 9001:2015 | JOSCAR

Plastic and metal materials
CNC machines
Machined parts each month

CNC Machining Processes

Looking for a reliable, quick-turn supplier of machined plastic and metal components? With hundreds of CNC machines, our unmatched in-house capacity ensures your parts are shipped on-time, every single time. At Protolabs, our CNC machining facilities are designed for both rapid prototyping and low-volume production of end-use components.

CNC Milling

CNC milling is a subtractive manufacturing process that uses 3-axis milling and 5-axis indexed milling processes to rapidly cut solid plastic and metal blocks into final parts.



CNC Turning

CNC turning with live tooling combines both lathe and mill capabilities to machine parts with cylindrical features from metal rod stock.



CNC Machining Materials




  • Aluminum
  • Brass
  • Carbon Steel
  • Copper
  • Mild Steel
  • Stainless Steel
  • Titanium



  • ABS 
  • Acetal
  • Delrin (POM)
  • HDPE 
  • Nylon
  • PEEK
  • PEI
  • PET



copper machined part

Design Guidelines for CNC Machining


Factory Capabilities

Network Capabilities

Maximum Part Size

3 axis: 254mm x 178mm x 95mm

5 axis: 66mm x 73mm x 99mm

(Max size for Aluminium 559mm x 356mm x 95mm)

650mm x 650mm x 300mm

Minimum Part Size 6.35mmx 6.35mm 0.50mm
Tolerances Typically, Protolabs can maintain a machining tolerance of +/- 0.1 mm. Parts may be as thin as 0.5 mm in regions as long as nominal part thickness is above 1 mm. Maximum depth that can be milled is 50 mm from either side of part. For specific milling dimensions by material, see maximum part extents for machining. +/-0.020mm
Radii Sharp inside corners on a part will be radiused (rounded) as a natural result of the CNC machining process.

Resulting radii will be identified before the part is milled.

A radii of 2 mm will be applied to sharp internal corners as standard.
Text • Recessed text should have a minimum stroke width of 0.5mm.
• The spacing between characters on raised text should be 0.5mm or greater.
• Minimum recessed text depth of 0.3mm.
• If design permits it, opt for recessed text versus raised.
Plastic and soft metals: Minimum width of 0.457mm, depth of 0.3mm. Example text size would be 16 point Arial Rounded MT font.

Hard metals: Minimum width of 0.838mm and depth of 0.3mm. Example text size would be 22 point Arial Rounded MT font.
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    Factory Capabilities Network Capabilities
Maximum Dimensions Diameter 75mm 431mm
Length 228mm 990mm
Minimum Dimensions Diameter 4mm 1mm
Length 1.27mm 0.5mm
Wall Thickness 0.5mm 0.5mm
Angle 30° Below 90° 
Tolerances +/- 0.1mm +/- 0.020mm
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Tolerances guaranteed through our digital network

Through our digital network of manufacturers powered by HUBS, we guarantee that our partners follow ISO 2768 standards for all CNC machined parts. For metal parts you have the choice of ISO 2768-m (medium) or ISO 2768-f (fine). Parts machined from plastics will follow 2768-m (medium). Geometric tolerances down to ±0.010 mm are possible but must be clearly indicated in technical drawings. Our network can achieve tighter tolerances on shafts and holes, with up to H7 fits (ISO 286-2), and on occasion even tighter tolerances via manual quoting.

All network partners follow ISO 2768 standards for CNC machining. It is possible to select medium or fine for metals. Further accuracy can be requested using 2D drawing tolerances. 
Our factory will either follow ISO 2768 standards for CNC machining or provide a general tolerance of ±0.1 mm. There are no selectable options, so 2D drawings are not required.

  Factory only Network metals only Network plastics or metals
Internal corner radii Detailed on 3D quote R2 mm as standard* R2 mm as standard*
Tolerance method nominal dimension# General Tolerance ISO 2768-f fine ISO 2768-m medium
0.5mm** to 3mm ±0.1 mm ±0.05 mm ±0.1 mm
Over 3mm to 6mm ±0.1 mm ±0.05 mm ±0.1 mm
Over 6mm to 30mm ±0.1 mm ±0.10 mm ±0.2 mm
Over 30mm to 120mm ±0.1 mm ±0.15 mm ±0.3 mm
Over 120mm to 400mm ±0.1 mm ±0.20 mm ±0.5 mm
Over 400mm to 1000mm ±0.1 mm ±0.30 mm ±0.8 mm
Over 1000mm to 2000mm Not applicable ±0.50 mm ±1.2 mm
Over 2000mm to 4000mm Not applicable Not applicable ±2.0 mm

# ISO 2768 is feature based: the tolerance band will apply to each and every feature on your part and is not related to overall part size.

*A radii of 2 mm will be applied to sharp internal corners as standard, more options can be requested.

** Please clearly indicate tolerances for nominal sizes below 0.5mm on your technical drawing

Tolerances guaranteed by Protolabs

Typically, Protolabs will maintain a general machining tolerance of ±0.1 mm or better.
The tolerance will be clearly stated on your quote, at this stage it is not possible to select tigher tolerances for factory options made in a few days, but our partner network can produce to tighter tolerances.
Parts may be as thin as 0.5 mm in regions as long as nominal part thickness is above 1 mm. Maximum tool depth that can be milled is 50 mm from any side of the part. For specific milling dimensions by material, see maximum part extents for machining.

Surface finish: Typically, Protolabs offer a surface finish of < 1.6 µm Ra (Roughness average) across the range of CNC materials. Ra 6.3 µm to Ra 0.8 µm are typical for general CNC machining. Optional bead blasting will result in a slightly rougher, but uniform, matt finish. See the surface finish guide for detailed images.

All components are inspected and measured, using calipers, micrometres, pin and thread gauges. Dimensional Inspection Reports (DIRs), using high accuracy Coordinate Measurement Machines (CMM’s) are also available on request.

ISO are the International Organisation for Standardisation and issue global standards to harmonise manufacturing. ISO 2768 defines three tolerances classes, fine, medium and course. Each class has a tolerance band proportional to the nominal dimension being measured. The main benefit of using a general tolerance, like ISO 2768-f, is that components can be produced directly from 3D CAD without the need for a 2D drawing. It also greatly simplifies producing a 2D drawing, as every dimension already has a tolerance applied, fewer tolerances need to be added to define critical dimensions.


CNC Threading

Threading Options and Guidelines

For machined parts, you can easily add threaded features, including key and coil inserts. These can be specified within your interactive quote. When a quote is returned, the 3D display will show which thread types are possible for each feature. Different threads (where possible) or no threads can be selected on a feature-by-feature basis.

Why Choose Protolabs for CNC Machining?

Advantages of CNC Machining

The subtractive process of CNC machining provides multiple benefits for both prototyping and low-volume production parts.

  • Precision and repeatability
  • Tight tolerances
  • Production-grade materials
  • Quick-turn parts within 1 day

CNC Machining Applications

CNC machining is widely used throughout the aerospace, medical, automotive industries for its ability to rapidly manufacture precise parts in production-grade materials. Typical CNC parts, include:

  • Housings and enclosures
  • Brackets
  • Fixtures for manufacturing
  • Gears and bearings
  • Internal mechanical components
  • Medical instrumentation

Have Complex Components for Machining?

Tighter tolerances down to ±0.020mm. Complete parts with no material left behind. Anodising at scale. Our manufacturing network of premium suppliers at Hubs can help. Get an instant quote for up to 1,000 parts today. 

Get Hubs Quote

What's in an Online CNC Quote?

Upload a 3D CAD file of your machined part and within a few hours we'll send you manufacturing analysis and an interactive quote. Within your quote you can modify materials and quantities and see pricing updates in real-time. Additionally, within your manufacturing analysis, you can assign threading with a click of your mouse.

Each CNC quote contains:

  • Real time, accurate pricing
  • Manufacturing analysis 
  • Threading assignments


How much does CNC machining cost?

Costs vary based on complexity, quantity and lead time. The best way to find out is to submit a 3D CAD model and get an interactive quote with design for manufacturability (DFM) feedback. Because we use proprietary software and automated fixturing processes, there are no up front non-recurring engineering (NRE) costs. This makes purchasing quantities as low as 1 to 200 parts cost effective. Prices compared to 3D printing are comparable to somewhat higher, but machining offers improved material properties and surfaces.

What types of threading options are available?

We offer UNF, UNC, and metric threads for machining along with coil and key inserts (but do not supply or install the inserts). These are available on both milled or turned CNC parts. View this page to see our complete threading options.

What is the maximum part size for CNC macining?

Maximum part size will vary based on your selected material. Our largest part size offered is 559mm x 356mm x 95.25mm and is available in Aluminiums. View this table to see maximum dimensions by material.

Where can I learn more about CNC design?

We have a variety of resources on CNC machining and how to design parts for the process. Here are some of our favorites:

What are the advantages of CNC machining?

Product designers and engineers choose CNC machining to rapidly produce prototypes and production parts. The manufacturing technology offers a high level of precision, engineering-grade materials, quick-turn lead times.

What is the digital network at Hubs?

Our global network of premium manufacturing partners powered by Hubs offers expanded capabilities, tighter tolerances, volume pricing, and the ability to handle more complex parts. You can visit and click on the ‘Capabilities’ tab in the navigation bar at the top of the page for the full list of capabilities available through Hubs.

CNC Cube

High Speed CNC Milling

Design for Speed

Following these design guidelines will result in an optimal and economical manufacturing time.


Design for Function

These features show off capabilities, but take longer to machine.

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