CNC Milling

Intro

In this article I will runover the basics of CNC, and then I will dive into some of the specifics.

A CNC machine is a form of Subtractive manufacturing, meaning you will start with a solid stock of material. Then remove stock with a spinning cutter, which is controlled by some high torque motors.

(MachiningToday, 2023)

Core Components of CNC machine

The material being cut is known as the workpiece, it is normally held down with fixtures or clamps. (12 Types of CNC Machines You Should Know About , 2024)

Cutting tools are the parts that actually do the removal of material. They come in different shapes and sizes depending on the task. End mills are used for removing stock of varying sizes, drills are for holes and lathe specific tools. (12 Types of CNC Machines You Should Know About , 2024)

 Tools & Tooling Basics

• Square End Mills

  • Square end mills are commonly used. They are often used for plunge cutting, where the end mill is pushed straight down into material. This is particularly handy when machining closed pockets.

    

• Ball End Mills

  • Ball end mills have a rounded tip. making them perfect for filleting or curvy, complex geometry. Ball end mills are great for the final finishing passes.

    

• Corner Radius End Mills

  • These are somewhere between Square End Mills and Ball End Mills. They are like a square end mill however they have a small radius in the corners. They are well suited for mould making (mould release). They are also good for reducing stress in a corner.

  • Corner Radius End Mills also have another advantage, square end mills are prone to getting chips on the corners of the mill. The rounded edges get rid of the weakest part of the design.

• Roughing End Mills

  • These are all about removing large amounts of material, quickly. Ready for a finishing pass once completed.

• Finishing End Mills

  • For producing a high quality finish on a part. These tools are often small and take a long time to remove material.

• Tapered End Mills

  • Ideal for making draft angles, especially if its just on a 3axis machine. It can cut deeply and precisely.

    

• Drill End Mills

  • For Drilling holes Precisely.

• Weldon End Mills

  • Iconic feature is flat side for agressive cutting

    

(matt-tools, 2024)

By using machining specific machining end bits, you can massively cut down in machining efficiency.

Machining efficiency is achieved through optimising tool path and what end mill is used for the job. Most often this means by removing bulk of material with a large, roughing end mill and then finishing with a smaller, rounded end mill.

 Materials

There are a large range of materials but I am going to break it down into Metals, Plastics And Natural fibres(wood)

Metals

Aluminium is the most used metal when it come to CNC. This is not only because it is extremly versitile, but also that it is easy to work with. Some key grades of allumiunium include:

• 7075 - Strong, Difficult to manufacture

• 6061 - Atmospheric Corrosion Resistant, Good all round alluminium. Great for moulds.

• 2042 - Super easy to manufacture. Can get damaged easily.

Stainless Steel

Stainless Steel is known for being strong and corrosion resistant, here are some common CNC:

• SS304 - High Corrosion Resistance - Used for pipes

• SS303 - Often used for gears, nuts and bolts

• SS316 - Strong and Weldable

Titanium

Titanium has a brilliant strength to weight ratio, its a great conductor and it is a popular choice for aircraft industry parts, biomedical and military. A grade which is oftenly used is Ti6Al4V.

.... (Smoothy, 2025)

Plastics

Injection moulding is great for complex plastic shapes, however CNC machining reduces upfront costs and quicker to produce. Making it ideal for prototypes.

CNCing plastic can be wasteful, especially if on scale. CNCing can be made more sustainable by using recyclable plastics (ABS, PETG, Acrylic , HDPE) and optimising tool path and stock material to avoid wastage.

Hard plastics CNC very well, soft or elastic ones like silicone or TPU arent suitable due to their deformation during cutting.

(Admin, 2025)

References

Intro

MachiningToday. (2023). Introduction to CNC Milling: What Beginners Need to Know. [online] Available at: https://machiningtoday.com/introduction-to-cnc-milling/ [Accessed 21 Dec. 2025].

‌

Core Components of CNC machine

12 Types of CNC Machines You Should Know About (2024). 12 Types of CNC Machines You Should Know About. [online] Shengen Sheet Metal. Available at: https://shengenfab.com/types-of-cnc-machines [Accessed 21 Dec. 2025].

‌

Tools & Tooling Basics

matt-tools (2024). 8 Different Types of End Mills: What You Need to Know - Toolholdernow. [online] Toolholdernow. Available at: https://toolholdernow.com/types-of-end-mills/.

‌

Materials

Smoothy, L. (2025). Choosing the Right Metal for CNC Machining | Get It Made. [online] Get-it-made.co.uk. Available at: https://get-it-made.co.uk/resources/choosing-the-right-metal-for-cnc-machining [Accessed 12 Jan. 2026].

Admin (2025). A Professional’s Guide To Cutting Plastics With CNC Machines - CNC World. [online] CNC World. Available at: https://cnc-world.co.uk/professional-guide-to-cutting-plastics-cnc-machines/ [Accessed 12 Jan. 2026].

‌

‌

Add another expandable item