Our CNC milling service delivers custom prototypes and production parts in as little as one day. We utilize both 3-axis and 5-axis indexed milling techniques to fabricate parts from over 30 types of engineering-grade plastics and metals. When ordering production parts, you can also benefit from competitive pricing for larger quantities, along with first article inspection (FAI) reporting, material certifications, and additional finishing options like anodizing and chromate plating.

Our CNC milling service is ideal for:

  • Functional prototypes
  • Jigs and fixtures
  • Low-volume production parts

CNC Milling Design Guidelines and Capabilities

Our standard CNC milling guidelines cover key design factors that can enhance part manufacturability, improve surface finish, and minimize production time.

Maximum Dimensions

The deepest cut achievable through milling is 2 inches (50.8mm) from either side of the part. For detailed milling dimensions based on different materials, refer to the maximum part size for CNC machining.

Material US Metric
3-axis** ABS
Acetal		 10 in. x 14 in. x 1.75 in. 254mm x 356mm x 44.5mm
3-axis** ABS
Acetal
Nylon		 22 in. x 14 in. x 0.75 in. 559mm x 356mm x 19.1mm
3-axis** Aluminum 22 in. x 14 in. x 3.75 in. 559mm x 356mm x 95.3mm
5-axis Hard metals*
Brass		 10 in. x 7 in. x 1.75 in. 254mm x 178mm x 44.5mm
5-axis Copper 10 in. x 7 in. x 2.75 in. 254mm x 178mm x 69.9mm
5-axis Aluminum
Plastic		 10 in. x 7 in. x 3.75 in. 254mm x 178mm 95.3mm

Hard Metals: Titanium (6Al-4V), Stainless Steel (303, 304, 316, 17-4PH), and Alloy Steel (4140)

Indicates two-sided machining is required.

Minimum Dimensions

US Metric
Size 0.25 in. x 0.25 in 6.35mm x 6.35mm
Nominal Thickness 0.040 in. 1.02mm

Threading

We offer UNC and UNF threads ranging from #2 to 0.5 inches, as well as metric threads from M2 to M12. It’s recommended to avoid designing internal threads directly in your part model.

We also offer the following for milled parts:

  • Helical inserts
  • Threaded key inserts
View Threading Options

Tolerances

We typically maintain a machining tolerance of ±0.005 in. (0.13mm). For optimal results, part features should be at least 0.020 in. (0.51mm) thick, with an overall part thickness of no less than 0.040 in.

Radii

Internal sharp corners will naturally become rounded during the CNC machining process. The resulting corner radii will be specified in your quote.

Text

  • Plastic and soft metals: Minimum line width of 0.018 in. (0.457mm) and depth of 0.0118 in. (0.3mm), with a recommended text size of 16 point Arial Rounded MT font.
  • Hard metals: Minimum line width of 0.033 in. (0.838mm) and depth of 0.0118 in. (0.3mm), with a recommended text size of 22 point Arial Rounded MT font.
  • For better results, recessed text is preferred over raised text when possible.

CNC Milling Materials

We offer a selection of over 30 high-quality plastic and metal materials, ideal for a wide range of part applications and industries.

Plastics

  • ABS
  • Acetal
  • CPVC
  • HDPE
  • LDPE
  • Nylon
  • PEEK
  • PEI
  • PET

Plastics

  • PMMA
  • Polycarbonate
  • Polypropylene
  • POM (Delrin)
  • PPSU
  • HIPS
  • PSU
  • PTFE
  • PVC

Metals

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

Anodizing and Chromate Coating Specifications

Anodize Hard Anodize Chromate
MIL-A-8625 Type II, Class 2 (Blk)
MIL-A-8625 Type II, Class 1(Clr)		 MIL-A-8625 Type III, Class 2 (Blk) MIL-DTL-5541 Type II, Class 3 (Clr)

Quick-turn Finishing

Here are the conditions to receive parts in as little as 4 days (1 day for expedited processing + 3 days for plating):

  • Eligibility for Aluminum 6061/6082 and 7075 materials
  • Threaded holes must be sealed
  • Masking not available

Premium Finishing Requirements

If you have AS9100 and ITAR compliance needs, consider our domestic precision machining service. For more intricate anodizing and plating needs, you can utilize our extensive digital network of manufacturers. This network is ideal for parts requiring specialized materials or finishes, like titanium or nickel, or unique color options.

Surface Finishing for Milled Parts

We generally debur (break) the edges on all machined parts. Machined plastic parts are typically left as-is, which may result in visible tool marks. For metal parts, however, there are more options available. Parts with sharp edges should be handled with caution.

Material: ABS Black

Finish: Broken edge

Material: ABS Natural

Finish: Broken edge

Material: Aluminum

Finish: Broken edge

Material: Aluminum

Finish: Bead Blast

Material: Aluminum

Finish: Sharp edge

Explore Our Digital CNC Machine Shop

Take a quick tour of our 215,000 sq. ft. CNC machining facility in Minnesota and discover how we produce parts in as little as 24 hours.

Understanding CNC Milling: Process and Functionality

CNC milling is a subtractive manufacturing process that involves securing a block of metal or plastic within a CNC machine. Guided by G-code, the machine swiftly removes material to shape the desired part. Our advanced 3-axis and 5-axis CNC mills are equipped with a variety of cutting tools to optimize efficiency and production speed.

Plastic parts are typically left with an as-machined finish, which may display visible tool marks. For metal parts, additional finishing options such as anodizing and chromate plating are available. Once machining and finishing are complete, parts are promptly packaged and shipped.