Depending on the application, the assortment of CNC machining tools can range from a single to dozens of tools. Each type of tool has its place in the machining process, of course, and the specific application will ultimately determine which tool or tool combination is best suited. The most common machining tools are discussed below.
Introduction to CNC Machine Tools
A CNC machine will only function with several tools in its arsenal. The specific machining tool or combination of tools that are used in any given machining operation will depend on the nature of the workpiece material, the required tolerances, the type of surface finish desired, and other factors.
What are CNC Machine Tools?
CNC machining tools are computer-controlled devices used in CNC machines to remove material from a workpiece by means of abrasion, cutting, or drilling. The CNC machine tool is typically operated via a computer program that tells the tool what and how to do it. This program is known as the G-code.
Classification of CNC Machine Tools
CNC machinists use many tools to cut, shape, and finish parts. These come in various shapes and sizes, each designed for a specific purpose. These CNC machinist tools can be broadly classified into three categories:
- Linear control CNC machining tools
- Point-to-point control CNC machining tools
- Multi-axis/contour control CNC machining tools.
Types of CNC Machining Tools
Different types of machine tools are used for different machining operations. CNC machine operators often change these during a machining process, or the machine will do so automatically. In this section, we will look at 9 of the most common machining tools and their capabilities. Note that this CNC machine tools list comprises the most used types.
1. End Mills
End mills are one of the most versatile types of machining tools. You can use them to mill flat surfaces, contoured surfaces, etc. They are available in various diameters, shank sizes, and cutting flutes to suit different machining needs.
End mills are typically used for roughing operations, where large amounts of material must be removed quickly. You can also use them for finishing processes, where precise tolerances and smooth finishes are required.
2. Face Mills
Face mills are used to remove material from flat surfaces. They typically consist of interchangeable carbide inserts mounted on a solid body. Face mills also use side-cutting lips to create a shearing action, which aids in material removal.
Face mills, with their side cutters, provide cost-effective CNC machining operations, given that you may not need to change the entire edge for each new machining job.
3. Thread Mills
These types of machining tools are used to create internal or external threads. They work like taps but are much more versatile, as they can create lines of different sizes and pitches.
Thread mills are also capable of creating left-handed or right-handed threads. These machining tools are ideal for cutting hard materials like a variety of metals.
4. Hollow Mills
As their name indicates, these CNC machine tools are cylindrical cutters with a hole in the center. With three or more cutting teeth, they machine cylindrical workpieces by enclosing the blank while it is being cut.
Hollow mills may be used to finish the exterior of a workpiece, or they may be used to create threaded interiors in the blank.
5. Slab mills
Slab mills are used to machine flat surfaces. They are similar to face mills but have a larger diameter body with more cutting teeth. Slab mills are also available in a variety of diameters and widths to suit different machining needs.
With their cutting located on the sides, these CNC machining tools are generally used to cut both small and large pieces of material.
6. Drill Bits
Drill bits primarily create holes in workpieces. They can be different sizes, depending on the type of hole that needs to be created. The most common types of CNC drill bits are twist drill bits, ejector drill bits, and center drill bits.
Twist drill bits are the most common type of drill bit and are used for drilling refined, cylindrical holes, while ejector drill bits are designed for drilling deep holes. Center drill bits are used to create a pilot hole for larger twist drill bits.
Reamers are used to enlarge and finish existing holes accurately. They are normally designed in a variety of sizes depending on the size and shape of the hole that needs to be reamed.
The main advantage of using these CNC machining tools is that you get higher precision and or accuracy for drilled holes. Reamers also help ensure tight tolerances are met, unlike when using a drill bit alone.
8. Gear Cutters
Gear cutters are used to create gears, splines, and sprockets. They come in a variety of sizes and shapes, depending on the number of teeth on the gear being cut.
Most often, these types of CNC machinist tools are employed in the manufacture of industrial equipment gears, automotive parts, and aerospace components.
9. Fly Cutters
Fly cutters are single-point cutting tools that are used to create large, flat surfaces. They consist of a solid body to which one or two cutting bits are attached.
Fly cutters are inexpensive CNC machining tools, despite providing a very smooth finish on the workpiece. However, multi-point cutting is more precise.
CNC Machine Tools Materials
Depending on the application and other requirements, CNC machine tools are made from various materials. The material type will dictate the machine tool’s overall strength and rigidity. The most common materials for devices used in CNC machine operations are high-speed steel (HSS), carbide, and carbon steel.
- High-Speed Steel (HSS): HSS is a steel alloy with carbon and other elements such as tungsten and chromium. It’s highly resistant to wear and can withstand high temperatures.
- Carbide: Carbide is a ceramic type made by bonding carbon with a metal, such as tungsten. It is extremely hard and can withstand high temperatures.
- Carbon Steel: This type of steel contains carbon and manganese. CNC machining tools made from this material are low-cost. These tools and commonly used to machine softer metals such as aluminum.
In addition to hardness and other attributes, a CNC machine tool’s price will usually depend on the type of material used to make it. Harder tools will generally cost more but will also last longer. Softer tools will be less expensive but must be replaced more often.
A machinist uses CNC machining tools to create parts and products from raw materials. Depending on the required type of part and its material, one tool may be better suited than another. For example, a face mill is best used to machine flat surfaces. In contrast, a hollow mill is better suited for machining cylindrical workpieces.