CNC Machining

Unionfab provides custom CNC Machining Services to engineers, product developers, designers, and more. We work with an extensive network of manufacturing partners that together have over 1,000 milling machines, which means we always have the capacity and very competitive prices.

We offer rapid CNC prototypes, small-batch machining, and high-volume production, with all orders serviced by Unionfab from end to end. Upload a CAD file to the Unionfab Instant Quoting Portal to get a price, lead time, and design-for-manufacturability feedback on your custom CNC parts.

Our CNC service offers metals and plastics and flexible production and shipping options to meet you at the perfect price and product development stage.

How CNC Machining  Works

CNC (computer numerical controlled) machining is a widely used manufacturing process that uses automated, high-speed cutting tools to form metal or plastic stock material designs. Standard CNC machines include 3-axis, 4-axis, and 5-axis milling machines, lathes, and routers. Appliances may vary in how parts are cut—the workpiece may remain in place while the tool moves, the tool may stay in place while the workpiece is rotated and moved, or both the cutting tool and workpiece may move together.

Skilled machinists operate CNC machines by programming tool paths based on the geometry of the final part. The part geometry information is provided by a CAD (computer-aided design) model. CNC machines can cut almost any metal alloy and rigid plastic with high precision and repeatability, making CNC machined parts suitable for nearly every industry, including aerospace, medical, robotics, electronics, and industrial. Unionfab offers CNC machining quotes on over 40 materials, from commodity aluminum and acetal to advanced titanium and engineered plastics like PEEK and Teflon.

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CNC Machining

CNC Machining Service is a widely used manufacturing process that uses automated, high-speed cutting tools to form metal or plastic stock material designs

Using advanced CNC Machines Service, we produce high-quality parts for a wide range of applications in the aerospace & defense, automotive, electronics, and other demanding industries.

Our technicians are highly-skilled operators and our organizational focus on quality and customer satisfaction at every level enables us to produce the precision parts you require for your project.

Why Make your CNC Machining at Unionfab?

  • Endless Options Choose from millions of possible combinations of materials, finishes, tolerances, markings, and certifications for your order.
  • Easy to Use Get your parts delivered right to your door without the hassle of sourcing, project management, logistics, or shipping.
  • Vetted Network We are ISO 9001:2015 certified and AS9100D compliant. Only the top shops that apply to become Suppliers make it through our qualification process.

Design Guidelines: CNC Machining

CNC Machining Capabilities
Feature Description
Maximum Part Size Milled parts up to 80” x 48” x 24” (2,032 x 1,219 x 610 mm). Lathe parts up to 62” (1,575 mm) length and 32” (813 mm) diameter.
Standard Lead Time 3 business days
General Tolerances Tolerances on metals will be held to +/- 0.005″ (+/- 0.127 mm) in accordance with ISO 2768 unless otherwise specified. Plastics and composites will be +/- 0.010”.
Precision Tolerances Unionfab can manufacture and inspect to tight tolerances per your drawing specifications including GD&T callouts.
Minimum Feature Size 0.020” (0.50 mm). This may vary depending on part geometry and chosen material.
Threads and Tapped Holes Unionfab can accommodate any standard thread size. We can also machine custom threads; these will require a manual quote review.
Edge Condition Sharp edges are broken and deburred by default
Surface Finish The standard finish is as-machined: 125 Ra or better. Additional finishing options can be specified when getting a quote.
US Metric
2.6 in. x 2.9 in. x 3.9 in. 66mm x 73mm x 99mm
SIZE 0.25 in. x 0.25 in. 6.35mm x 6.35mm
NOMINAL THICKNESS 0.040 in. 1.02mm
PLASTIC Edges broken with visible tool marks
ALUMINUM Edges broken with visible tool marks, edges broken with light bead blast, or sharp edges with visible tool marks
ALL OTHER METALS Edges broken with visible toolmarks or edges broken with light bead blast

Recommended text considerations for CNC milling:

  • Plastic and soft metals: Minimum width of 0.018 in. (0.457mm), depth of 0.0118 in. (0.3mm).

    Example text size would be 16 point Arial Rounded MT font.

  • Hard metals: Minimum width of 0.033 in. (0.838mm) and depth of 0.0118 in. (0.3mm).

    Example text size would be 22 point Arial Rounded MT font.

  • If design permits it, opt for recessed text versus raised.

CNC Machining Material Options

Nylon 66

Nylon 66


Nylon 66 is a type of polyamide or nylon. It, and nylon 6, are the two most common for textile and plastic industries. Nylon 66 is made of two monomers each containing 6 carbon atoms, hexamethylenediamine and adipic acid, which give nylon 66 its name.


Nylon 6/6 is one of the most versatile engineering thermoplastics. It is popular in every major market using thermoplastic materials. Because of its excellent balance of strength, ductility and heat resistance, nylon 6/6 is an outstanding candidate for metal replacement applications. Nylon 6/6 is very easy to process with a very wide process window. This allows it to be used for everything from complex, thin walled components to large thick walled housings




Tensile Strength, Yield (MPa)
Elongation at Break (%)
Hardness (Shore D)
Heat Deflection Temperature (°C)
Melting Point (°C)

Multi Color

Acrylic is a tough material that has numerous benefits over glass. For one, acrylic can be easily machined whereas glass cannot. This gives you the option of CNC machining in acrylic when the task requires both complex geometry and high levels of optical clarity in the final part. Acrylic’s clarity makes it ideal for inspection windows, chemical testing hardware, and instrumentation covers.

Compare our 3D Printing Services

Service Lead Times Materials Tolerances Max Part Size
SLA 1 – 3 days Resin / Somos +/- 0.003 in. 800 x 800 x 550 mm
SLS 2 – 5 days PA12/ PA12GB +/- 0.002 in. 350 x 350 x 400 mm
MJF 2 – 5 days PA12/ PA12GB +/- 0.002 in. 380 x 280 x 380 mm
FDM 2 – 5 days PLA / ABS  +/- 0.003 in. 500 x 500 x 400 mm
Poly Jet 2 – 5 days Resin +/- 0.003 in. 490 x 390 x 200 mm