Our CNC Milling Capabilities

RapidDirect provides 3 axis, 4 axis CNC milling, and 5-axis CNC milling centers according to your custom needs, from rapid prototyping to production parts.

3-axis, 4-axis CNC Milling

3-axis and 4-axis CNC milling machines are the most commonly used CNC milling process, which has lower tolerance level, but more affordable price. We recommend 3-axis or 4-axis CNC mill machining for producing parts with simple geometries.

Maximum part size

Aluminum, copper, brass, and plastics2000x1500x200mm78.7×59.0x7.8 in
Stainless steel, tool steel, alloy steel & mild steel1200x800x500mm47.2×31.4×27.5 in
Minimum feature sizeØ 0.50 mmØ 0.019 in


Metal materials+/-.005 in+/-.127 mm
Plastic materials+/-.010 in+/-.254 mm
3-axis, 4-axis CNC Milling

5-axis CNC Milling

5-axis CNC milling center represents the highest manufacturing capabilities that CNC milling service could reach. It has higher price, but significantly higer efficiency comparing with 3-axis CNC milling, more suitable for producing parts with complex geometries.

Maximum part size

Maximum part size650 x 650 x 300 mm25.5 x 25.5 x 11.8 in
Minimum feature sizeØ 0.50 mmØ 0.019 in


Metal materials+/-.005 in+/-.127 mm
Plastic materials+/-.010 in+/-.254 mm

5-axis CNC Milling

Why CNC Milling with RapidDirect

dmf feedback and online quote

Instant Quoting

No more email back-and-forth, by simply uploading your design files and selecting the material and surface finish, our big-data-driven platform calculates an accurate and competitive CNC quotation in real-time.

strong capabilities

Strong Capacity

Having been in this industry for nearly 2 decades, RapidDirect has developed a team of engineers with profound CNC project experience. Get machining parts suggestions that achieve the same function at a lower cost.

Engineering support icon

Engineering Support

It is our tenet to always put the customers at the first place. We proudly have a dedicated customer success team that restlessly offers online chatting, email, and the phone supports to ensure the parts meet your expectations.

1M +
Parts Produced
10,000 +
Customers Served

Real Customer Feedback

The parts arrived on Monday. Thanks for the prompt service and attention to our order. We have inspected the parts and installed them in one of our assemblies. The quality, fit, and finish are excellent. I will place an order for a larger quantity.

— Jessie Beck

Getting the quotation online is a mind-blowing experience, and the result turned out to be impressive. It saves me a lot of time and efforts on communicating. 

— Toby Dalton

I have received the parts yesterday. Thanks for supporting my project within such urgent lead-time. The manufacturing process updates, and logistics tracking helped a lot. I can see that everything’s under control, very practical function! 

— Laurel Rivas

Materials for CNC Milling Parts

The various available materials is another advantage of CNC milling. At RapidDirect, you can choose from over 50 milling metals and plastics. In addition, we also provide material certification at your request.

Aluminum is a highly ductile metal, making it easy to machine. The material has a good strength-to-weight ratio and is available in many types for a range of applications.

Available Subtypes

  • Aluminum 6061

  • Aluminum 6061-T651

  • Aluminum 6063

  • Aluminum 7075

  • Aluminum 6082

  • Aluminum 2024

  • Aluminum 5052

  • Aluminum 5083

  • Aluminum ADC12 (A380)

cnc machining raw material - aluminum

Copper displays excellent thermal conductivity, electrical conductivity and plasticity. It is also highly ductile, corrosion resistant and can be easily welded.

Available Subtypes

  • Copper
  • Copper 101
  • Copper for EDM
  • Beryllium copper
  • Chromium zirconium copper
  • Tungsten copper
  • Antimony copper
cnc machining raw material - copper

Brass has desirable properties for a number of applications. It is low friction, has excellent electrical conductivity and has a golden (brass) appearance.

Available Subtypes

  • Brass 2680
  • Brass H59
  • Brass H62
  • Brass 260
  • Brass 385
  • Brass CAD260
  • Brass 360
  • Tin phosphor bronze
  • Aluminum bronze plate
  • Tin bronze
cnc machining raw material - brass

Steel is known for its high tensile strength and low costs. It is a ubiquitous material in the construction, infrastructure, automotive, maritime, tooling, manufacturing and defense industries.

Available Subtypes

  • 1045 Steel (45 #)

  • 1008 Steel

  • 1018 Steel

  • 1020 Steel

  • 1025 Steel

  • 11Smn30 Steel

  • 1215 Steel

  • 4041 Steel

  • 40Cr Steel

  • 4130 Steel

  • 4137 Steel

  • 4140 Steel

  • 42 Crmo Steel

  • 4340 Steel

  • 4J36 Steel Alloy

  • 5140 Steel

  • 5160 Steel

  • 60Si2Mn Steel

  • 65Mn Steel

  • A2 Tool Steel

  • A36 Steel

  • C3600

  • Class 8 Gray iron

  • Cr12Mov Steel

  • D2 mould steel

  • DC-01 Steel Cold rolled steel

  • EN16T Steel

  • EN3B Steel

  • EN8T Steel

  • H13 Steel

  • Inconel Steel

  • Invar 36 Steel

  • NAK80 Steel

  • P20 Steel

  • S136 Steel

  • S7 Steel Tool Steel

  • SK5 Steel

  • SKD11 Steel

  • SKD61 Steel

  • SKH51 Steel

  • ST37 (Q235) Steel

  • ZGmn13-5

  • Galvanized Steel / SGCC / SECC

  • S7 Steel

  • SCM440 (40CrMo) Steel alloy

  • 52100 Bearing Steel

cnc machining raw material- steel

Stainless steel typically contains a minimum of 10% chromium by weight. It is a popular metal within a broad range of industries, including construction, automotive, aerospace and more.

Available Subtypes

  • SUS304

  • SUS303

  • SUS301

  • SUS316

  • SUS316L

  • SUS401

  • SUS416L

  • SUS416

  • SUS420

  • SUS201

  • SUS430

  • SUS431

  • SUS440C

  • SUS410

  • SUS630 / 17-4PH

  • PP631 / 17-7PH

raw material - stainless steel bar / rod

Titanium is resistance to corrosion, chemicals and extreme temperatures, and has excellent strength-to-weight ratio. It has broad adoption in the aerospace, medical and defense industries.

Available Subtypes

  • TC4 Titannium Alloy
  • TC5 Titanium Alloy
  • Military-grade titanium Alloy
  • Food-grade titanium Alloy
  • R53400 Titanium Alloy 9
cnc machining product - titanium

Plastic is an indispensable part of our everyday world. It is known for its lightweight, high strength-to-weight ratio, electric insulation, low price, suitable for mass production, etc. The application of plastics is so wide that you can always see it in all industries.

Available Subtypes

  • ABS
  • PC
  • ABS+PC
  • PMMA
  • POM
  • PP
  • PA
  • PEEK
  • PET
  • PVC
  • PPSU
  • PPS
  • PTFE
  • PBT
  • PE
  • PEI
  • HDPE
  • UPE
  • CPVC
  • EPP
  • FR-4
  • HIPS
  • LDPE
  • PAI
  • PETG
  • PPA
  • PS
  • PVDF
  • Bakelite
Engineering Plastics

Surface Finishes for CNC Milling

CNC milling parts are left as-milled, and surface finish can change the appearance, surface roughness, hardness and chemical resistance of the produced parts. Determined by the material using, a part can have one to serval available surface finishing options. Learn more at our surface finish page.

Anodizing changes the surface state and performance of the material, thus improving corrosion resistance, enhancing wear resistance and hardness, and protecting the metal surface.

Available materials:

surface finish - anodizing

Bead blasting directs abrasive material onto the surface, so as to alter and improved the properties of the workpiece surface - such as roughness and uniformity.

Available materials:
Aluminum, stainless steel, steel, copper, bronze, titanium, magnesium, zinc, all plastics

surface finish - bead blasting

Powder coating is a surface finishing technique used to create a hard finish tougher than normal paint. Commonly used for coat metal parts.

Available materials:
Aluminum, stainless steel, steel, copper, bronze, titanium, magnesium, zinc

surface finish - powder coating

Electroplating bonds fine layers of metal to the surface of another metal, thus reaching either functional, decorative, or corrosion-related properties.

Available materials:
Aluminum, stainless steel, steel, copper, bronze, titanium, magnesium, zinc

Electroplating Image

Polishing is the process of creating a smooth and shiny surface, it produces a surface with significant specular reflection, so as to improve the appearance of new or used metal parts.

Available materials:
Aluminum, stainless steel, steel, copper, bronze, titanium, magnesium, zinc, all plastics

Polishing Image

Brushing is a surface treatment process in which abrasive belts are used to draw traces on the surface of a material, usually for aesthetic purposes. Most commonly applied to aluminum.

Available materials:
Aluminum, stainless steel, steel, copper, bronze, titanium, magnesium, zinc, all plastics

Brushing Image

Painting involves spraying a layer of paint onto the surface of the part. It can improve the part's aesthetic appearance and can add a protective layer on the parts.

Available materials:
Aluminum, stainless steel, steel, copper, bronze, titanium, magnesium, zinc

Painting Image

Quality Reports & Certifications

full dimensional quality reports


During the production of every project, we strictly obey the ISO 9001:2015 requirements. We can provide material certifications, SGS, and ROHS certifications, please contact our sales team at your request.

Material certification

Quality inspection

We have a team of dedicated engineers who always feedback best practices for you. During CNC milling processes, the quality team conducts In-Process Quality Control every 30 minutes to minimize risks.

First part verification

Additional service

RapidDirect respects your intellectual properties, we always welcome NDA agreements for all order. For production orders, you can apply First-Article Inspection. In the end, you can always enjoy our Rework & Refund Policy.

CNC Milling Design Recommendations

The table below summarizes some basic guidelines in the design of CNC milling. Following these recommendations can greatly benefit the production efficiency and reduce cost. Learn more about CNC design guides.

Recommended: β…“ times cavity depth (or larger)

By ultilizing the recommended value for internal corner radii, it is sure that a suitable diameter tool is available and aligns with the guidelines for the recommended cavity depth.

Internal Edges Image

Recommended: 0.8 mm (metals), 1.5 mm (plastics)

The less wall thickness, the less material stiffness. It will lead to the vibrations during machining and lower accuracy. We recommend you use even larger minimum wall thickness for plastics.

Thin Walls Image

Recommended Diameter: standard drill bit sizes

Recommended Depth: 4 - 40 times nominal diameter

The tools used for drilling holes are either drill bit or end mill tool. For high accuracy holes smaller than βŒ€20 mm, using a standard diameter is recommended.

Holes Image

Recommended size: M6 or larger

Recommended length: 3 times nominal diameter

Threads are divided into internal and external ones. Internal threads are cut with taps, while external threads with dies. Taps and dies can be used to cut threads down to M2. CNC threading tools are common and they are preferred, as they limit the risk of tap breakage.

threads cnc milling machine Image

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CNC Milling Applications

As a result of its wide options of materials and high tolerances standard, CNC milling is a crucial process in many industries such as aerospace, automotive, energy, industrial machinery, medical, robotics, etc. Furthermore, CNC milling doesn't come along, it is also vital to many other manufacturing processes.

Rapid Tooling
Rapid Tooling

Our CNC machining service is ideal for rapid tooling, we specialize in the production of injection molding tools and other tooling applications.

Rapid Prototyping
Rapid Prototyping

CNC Machining is ideal for prototyping applications. We work with our customers to meet their manufacturing requirements and quality standards.

Direct Manufacturing
End-Use Production

CNC Machining is commonly used for end-use production because of its precision, high-quality finishes, and broad material compatibility.

Instant Quote & Order

Only 4 simple steps to complete your project. Follow the instruction and give it a try!

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Place an order
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