Custom Online CNC Machining Services

Get instant quote for rapid prototypes and production parts with Unionfab’s Online CNC Machining Service. We are ISO 9001:2015, ISO 13485 and AS9100D certified.

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Why Use Unionfab for Custom Online CNC Machining Services?

Unionfab acquired Midea's machining factory in 2019. It has more than 400 sets of various types of machining equipment. The factory is good at precision parts processing and small batch parts processing. At the same time, we have a professional supply chain department, using China's excellent machining suppliers to meet the needs of different industries. We are committed to helping you bring products to market quickly, providing rapid prototyping, small-batch machining, and high-volume production. Simply upload your CAD files to Unionfab's Instant Quote system, and you will receive competitive prices and a fast lead time in just a minute. For your manufacturing needs, we provide instant quotations for a variety of metals and plastics.

Unionfab ensures consistent, expected quality in our products with our ISO 9001:2015, ISO 13485, and AS9100D certified quality management system. We also accept technical drawings, and our engineering team will ensure you receive quality CNC machined parts on time.

Use the 3D viewer above to preview Unionfab's part rendering features.

What is CNC Machining?

CNC, or computer numerical control machining, is a subtractive manufacturing process that employs automated, high-speed cutting tools to create custom shapes and designs from metal or plastic stock. Standard CNC machines mainly comprise 3-axis, 4-axis, and 5-axis milling machines, lathes, and routers. The way these machines cut CNC parts may vary. In the case of milling machines, the workpiece remains stationary while the tool is moved; with lathes, the tool remains stationary while the workpiece is rotated and moved; and in the case of routers, both parts move together.

The basic CNC process involves three steps. First, the engineer designs the CAD model of the part. Then, the machinist converts it into a CNC program (G-code), which is used to set up the machine. Finally, the program guides the machine throughout the process as it executes the necessary machine operations to produce a custom-designed part or product. CNC machines can process almost every material, including metals and plastics, as well as foam, composites, and wood. Custom machined parts are suitable for a wide variety of industries, including automotive, aerospace, electronics, industrial, robotics, construction, and agriculture. Unionfab offers CNC services and provides custom CNC quotes for hundreds of materials, including ordinary aluminum alloy, high-strength aircraft-grade aluminum alloy 7075, brass, red copper, bronze, beryllium copper, ordinary steel, maraging steel, stainless steel, powdered high-speed steel, etc. We also work with various plastics, such as Peek, Teflon, nylon, anti-static plastic, and other engineering plastics. Additionally, we offer a range of synthetic materials, including synthetic stone, glass fiber, tungsten steel, ceramics, titanium alloys, and more.

Custom CNC Machining Services: Machining, Turning and Milling

Custom CNC Milling Services

CNC milled prototypes and production parts in days | ISO 9001:2015 | ISO 13485 | AS9100D

Custom CNC Milling Services

CNC Turning Service

CNC turned prototypes and production parts in days | ISO 9001:2015 | ISO 13485 | AS9100D

CNC Turning Service

High Volume CNC Machining Services by Unionfab

High Volume CNC Machined prototypes and production parts in days | ISO 9001:2015 | ISO 13485 | AS9100D

CNC Machining Tolerances

Maximum Part Size: Milled parts can be as large as 80” x 48” x 24” (2,032 x 1,219 x 610 mm). Lathe parts can reach up to 62” (1,575 mm) in length and 32” (813 mm) in diameter.

Standard Lead Time: 7 business days.

General Tolerances: Tolerances for metals will be maintained within +/- 0.005” (+/- 0.127 mm) in accordance with ISO 2768, unless otherwise specified. Tolerances for plastics and composites will be +/- 0.010”.

Precision Tolerances: Unionfab can manufacture and inspect to tight tolerances as per your drawing specifications, including GD&T callouts.

Minimum Feature Size: 0.010” (0.254 mm), dependent on part geometry and chosen material.

Threads and Tapped Holes: Unionfab can accommodate any standard thread size. We also offer the service of machining custom threads. Consequently, these requests will undergo a manual quote review process.

Edge Condition: Sharp edges are broken and deburred by default.

Surface Finish: The standard finish is “as machined”, with a surface finish of 125 Ra or better. Additional finishing options can be specified when obtaining a quote.

Metal CNC Machining Materials
Plastic CNC Machining Materials
CNC Machining Finishes
CNC Machining Design Guidelines

Internal Corner Fillets

Design internal corner fillets with a size that is 0.020” - 0.050” greater than the radii of a standard drill. Use a drill diameter to depth ratio of 1:6 (1:4 recommended) as a reference for determining internal corner radii.

Floor Fillets

Design floor fillets smaller than corner fillets to ensure that the same tool used for creating corner fillets can effectively clear material from the interior.


Design undercuts to standard sizes and position them away from corners to enable the cutting tool to easily reach and remove material during the manufacturing process.

Tapped/Threaded Hole Depth

Provide tool clearance slightly beyond the tapped hole depth to ensure that the threading tool has adequate space to fully form threads without interference from the hole bottom.


By minimizing the number of small cuts in CNC machining, CNC machining costs can be significantly reduced. When considering necessary features, focus on the product’s core functionality to strike a balance between function and aesthetics.

CNC Machining FAQs

Advantages and Challenges of CNC Machining

CNC milling and turning offer numerous advantages in terms of accuracy, repeatability, and production efficiency. Tight tolerances ranging from +/- 0.001″ to 0.005″ can be achieved, depending on specifications. Once a machine is programmed with the necessary instructions, it can operate continuously for extended periods, including 24 hours a day, 7 days a week if required. This capability ensures a steady supply of parts on demand, making CNC milling an excellent choice for industries with high production requirements or tight deadlines.

One of the key advantages of CNC machining is the ability to create one-off parts or custom CNC parts. This is particularly valuable when dealing with legacy components that are no longer in production or require modifications to meet specific requirements. It is now possible to scale single-part production to meet the demands of runs exceeding 10,000 units. The turnaround time for CNC machined parts largely depends on factors such as the unit number, size, and complexity. In some cases, manufacturers can deliver CNC machined parts within a day. With shipping and delivery, deadlines can be met within a week.

CNC machined parts have the same excellent physical properties as bulk materials. More than 50 industrial-grade metals, alloys, and plastics can be machined with CNC milling and turning. The selection includes aluminum, brass, bronze, titanium, stainless steel, PEEK, ABS, and zinc. The only material requirement for CNC machining is that the part must be hard enough to be fixtured and cut.

CNC Machining Applications

Rapid Tooling

Using CNC machining to cut a wide variety of fully dense materials, such as aluminum 5052 and stainless steel, ensures that the resulting fixtures or molds will be strong and durable.

Rapid Prototyping

We offer a range of affordable metal alloys (like Aluminum 6061) and plastics (like acetal and ABS). By leveraging the expertise of our skilled machinists, we can ensure the precise and accurate manufacturing of prototypes.

End-Use Production

The combination of performance-enhancing finishes, precision tolerances as low as +/- 0.001”, and a wide range of certifiable material options makes CNC machining an exceptional technology for producing end-use parts.