In manufacturing and engineering, milling is a cutting process where a machinist uses a milling cutter to remove material from the surface of a workpiece. Milling cutters are available in different shapes and sizes —a necessary feature to accommodate the variety of axes, cutter head speeds and pressures required to machine custom parts to precise tolerances.
For decades, milling was performed manually by humans using heavy machinery. But modern milling is mainly done through a Computer Numerical Control (CNC) machine, which uses a computer to control the milling process. This introduces higher precision, better accuracy and improved production rates to your cutting projects. It’s no surprise then that the global CNC machining market is predicted to reach $76.22 billion by the end of 2021.
However, there are still cases when manual milling is useful, such as when a piece needs a shorter turnaround (manual milling requires fewer steps than CNC milling). However, manual milling requires a high degree of technical skill and experience to get the same results as a CNC machine.
Types of Milling Cutters to Get
Either way, your shop will need various milling cutters to accommodate different types of cutting jobs and materials. Here are six types of milling cutters worth getting for your CNC machine shop.
1. Face Mills
A face mill or shell mill is a circular milling tool with a flat end and carbide-tipped teeth along its circumference. These tips can be replaced when they wear out or sustain damage. These cutters are typically used to create a flat face on the surface of a metal plate or bar workpiece. Their wider diameter makes them ideal for cutting away more material from a surface.
2. Slab Mills
Also known as plain or surface mills, slab milling cutters are often used with horizontal manual milling machines for machining large surfaces. These mills typically have two types of teeth (coarse teeth and fine teeth), distributed evenly across the circumference of the milling cutter.
3. End Mill Cutters
End mill cutters are used for machining the sides and faces of metal workpieces. They feature a rotating cylindrical shank with teeth at the tip. Although they look similar to drills, the cutters are specifically used for end milling operations. This is a machining process for creating cut features such as channels, slots, fins, and columns. For this reason, end mills are often called the cutters of the milling world.
4. Roughing End Mills
Also known as “rippa” cutters and hog mills, roughing end mills are designed for deep splitting and heavy side cuts, removing large amounts of material in the process. They are not a finesse tool and should only be used for heavier operations.
Roughing end mills also have a serrated cutting edge that produces little to no vibration during machining. They leave behind a rougher finish, hence the name.
5. Porcupine Mills
Porcupine mills, also known as flute milling cutters, are typically used for heavy-duty machining of wide and rough edges, cavities, and deep shoulders. Their soft cutting ability allow them to remove large amounts of material, even on low-performance machines.
6. Side and Face Cutters
Side and face cutting tools (sometimes erroneously called slide and face cutters) have cutting teeth along their circumference and sides. These milling cutters come in a wide variety of widths and diameters and are generally used for making unbalanced cuts (i.e., cuts on one side of the tool).
Choose the Right Milling Tool for Your CNC Operation
Ultimately, the right milling tool depends on your specific machining operation. While you’re likely to come across other types of devices as you take more work, this list of CNC milling tools should serve as a good foundation that you can build upon.
Gary Clegg has been in the manufacturing and engineering industry for over 35 years, having worked his way up from an apprentice to production manager. Gary is a time-served CNC machine engineer and has experience in all engineering fields, including milling, drilling, turning and threading. After leaving the shop floor to join the tool supply industry, he gained additional knowledge and experience in the tool and work holding category. This makes him an expert in static and driven tools, with contacts with all leading CNC manufacturers.