CNC machining is widely used in various industries due to its high accuracy. In the CNC machining process, CNC machine tools contribute a lot to product accuracy. There are many types of CNC machine-cutting tools used for different applications. In this blog, KUSLA will share with you everything about CNC machine tools.
What is a CNC machine tool?
A CNC machine tool is a cutting device used on a CNC machine to remove material from a solid block of material. It rotates or moves with the spindle of the CNC machine to cut materials from the workpiece. The CNC machining tools are divided into turning tools, milling tools, and more.
Structure of CNC machine tools
The structure of various tools consists of the clamping part and the working part. In integral structure tools, both the clamping part and the working part are made on the tool body; for inserted-tooth structure tools, the working part (teeth or blades) is inserted into the tool body.
There are two types of clamping parts for tools: with holes and with shanks. Tools with holes are mounted on the main or sub spindles of the machine tool through internal holes, transmitting torsional torque via axial or end keys, such as cylindrical milling cutters, modular face milling cutters, and so on.
Tools with shanks usually come in three types: rectangular shank, cylindrical shank, and taper shank. Turning tools, planers, and the like generally have a rectangular shank; taper shank relies on the taper to withstand axial thrust and transmits torque through frictional force; cylindrical shank is generally suitable for smaller tools like twist drills and end mills, and torque is transmitted through the frictional force generated during clamping. The shank of many shank-type tools is made of low alloy steel, while the working part is made of high-speed steel and welded to the shank.
Types of CNC machine tools
CNC machines have gradually become standardized and serialized. There are various methods for classifying CNC tools.
Based on tool structure, they can be divided into:
- Integral type;
- Inserted type, using welding or mechanical clamping connection, with mechanical clamping further divided into non-indexable and indexable types;
- Special types, such as composite tools, damping tools, and so on.
Based on the cutting process, they can be divided into:
- CNC Turning tools, including outer circle, inner hole, thread, etc.
- CNC Drilling tools, including drills, reamers, taps, etc.
- CNC Milling tools.
Common CNC Milling Tools
Face Milling Cutter (Flat Mill)
A face milling cutter, also known as a flat mill, is surrounded by primary cutting edges with secondary cutting edges at the bottom. It is used for milling, grooving, and contouring surfaces.
Ball End Mill
A ball end mill, also referred to as an R mill, with a spherical bottom edge. The ball end mill is primarily used on 3D mold milling machines, especially for precision machining and corner cleaning.
Bull Nose Cutter
A bull nose cutter, also known as a flat-bottomed R mill, is used for rough machining, flat surface finishing, and contour profiling. Compared to face milling cutters and ball end mills, the bull nose cutter combines the advantages of both offering better work efficiency.
Common CNC Turning Tools
External Turning Tool
The external turning tool is used for CNC turning external cylindrical surfaces, end faces, hole bottoms, and more. Common types include straight-edge external turning tools, V-edge external turning tools, and chamfered-edge external turning tools.
Internal Turning Tool
The internal turning tool is used for turning the inner surface of holes and is divided into blade-type and lathe-type for cutting.
Grooving Tool
The grooving tool is used for turning axial grooves on parts like slots and gears. Depending on the groove shape and application, grooving tools are divided into various types such as saw-tooth grooving tools, cylindrical-tooth grooving tools, orthogonal grooving tools, and arc-shaped grooving tools.
Thread Turning Tool
The thread-turning tool is used for turning internal and external threads and is divided into insert-type and groove-type. Cemented carbide is commonly used as the material for thread-turning tools.
Parting Tool
The parting tool is used to cut through workpieces during turning operations and is commonly made from cemented carbide or high-speed steel.
Common CNC Drilling Tool
Drilling tools are hole machining tools used for drilling holes in solid materials or enlarging existing holes. Depending on the construction and purpose of the drill bit, drilling tools can be divided into twist drills, flat drills, center drills, and deep hole drills.
Twist Drill
A twist drill is a tool that cuts round holes in a workpiece by rotating around its fixed axis. Its name comes from the helical shape of the chip flutes which is similar to a “twisted” appearance.
Flat Drill
The flat drill is the earliest type of drill used for hole machining. The flat drill has a simple structure, easy manufacturing, low cost, small axial dimensions, and good rigidity.
Center Drill
The center drill is a type of drill used for machining round holes, suitable for processing harder materials such as metal, ceramics, glass, etc.
Deep Hole Drill
A deep hole drill is a type of drill specifically designed for machining deep holes, and it can be divided into external chip removal and internal chip removal types.
Reaming Drill
A reaming drill is a tool used to enlarge the hole diameter and improve machining quality.
Reamer
A reamer is a rotating cutting tool with one or more teeth used to remove a thin layer of metal from the surface of an existing hole to improve the quality of the hole.
Boring Tool
A boring tool is used for internal hole machining, hole enlargement, contour replication, and similar applications. Generally, with a round shank, it is commonly seen in vertical lathes.
Thread Tap
A thread tap is a tool used for machining internal threads. It can be categorized based on its design into spiral flute taps, helical angle taps, straight flute taps, and pipe thread taps.
CNC machine tool materials
Carbon Steel
Carbon steel is an alloy made of iron and carbon. Tools made from carbon steel material have good wear resistance. They are used for machining soft metals like aluminum, copper, and magnesium.
High-Speed Steel (HSS)
High-speed steel has high strength, toughness, and a certain level of hardness and wear resistance which can meet various tool requirements. HSS tool is commonly used for machining iron risers, milling slots, and drilling oil holes in piston manufacturing.
Cemented Carbide (Hard Alloy)
Cemented carbide is produced by powder metallurgy using hard metal carbides(such as WC, TiC, TaC, NbC) and a metallic binder(such as Co, Ni). The hardness of cemented carbides is higher than that of HSS, Therefore, the cemented carbide tool has a much higher cutting performance than the HSS tool with increased tool durability and 4-10 times higher cutting speeds.
Diamond
Diamond is the hardest mineral material with excellent thermal conductivity. Its wear rate when paired with various metals or non-metal materials in friction is only 1/50 to 1/800 of that of cemented carbide. It is the ideal material for making cutting tools.
Polycrystalline Cubic Boron Nitride (PCBN)
PCBN is formed by sintering CBN micro-powder with a small amount of binding phase (Co, Ni, or TiC, TiN, Al2O3) using a catalyst at high temperature and pressure. It has high hardness (second only to diamond), heat resistance (1300-1500°C), excellent chemical stability, much higher thermal stability (up to 1400°C) and thermal conductivity than diamond tools, and low friction coefficient, but its strength is lower.
Ceramics
The main advantages of ceramic cutting tool materials are their high hardness and wear resistance, with a room temperature hardness of 91-95 HRC. They exhibit high heat resistance, maintaining a hardness of 80 HRC at 1200°C.
Properties of CNC machine tools
High Hardness
The hardness of tool materials must be higher than that of the workpiece material. Otherwise, the geometric shape of the tool edge cannot be maintained at high temperatures. This is a characteristic table of tool materials.
| CNC Tool Material | Hardness (HV) |
| Diamond | 8500-10000 |
| Polycrystalline Cubic Boron Nitride (PCBN) | 4700-5000 |
| Ceramics | 1900-2200 |
| Cemented Carbide (Hard Alloy) | 1800-2000 |
| High-Speed Steel (HSS) | 850-1100 |
| Carbon Tool Steel | 600-700 |
High Strength And Toughness
The material in the cutting part of the tool must withstand significant cutting forces and impacts during machining which means tool materials must possess sufficient strength and toughness.
High Wear And Heat Resistance
The higher the hardness of the tool material, the better its wear resistance. A higher high-temperature hardness indicates better heat resistance and stronger resistance to plastic deformation and wear at high temperatures.
Good Thermal Conductivity
Higher thermal conductivity indicates better heat conduction, allowing heat generated during cutting to dissipate more easily, thus lowering the temperature of the cutting area and reducing tool wear.
Good Processability And Economy
Tool materials should easily be machined so that the cost of CNC machine tools will not be high which is good for business.
Chemical Stability
Tool materials need to be stable without any chemical reactions with the surrounding media at high temperatures.
Coatings for CNC machine tools
Titanium Nitride Coating
Abbreviated as TiN coating, it is a hard and thin film coating applied to the surface of tools. The TiN coating is golden and often used for milling and drilling tools, it can improve the performance and durability of tools.
Titanium Carbonitride Coating
Titanium carbonitride coating, abbreviated as TiCN coating, is used to enhance tool hardness and achieve good surface lubrication. It is commonly used on high-speed cutting tools.
Diamond Coating
Diamond coatings improve the wear resistance of non-metallic material cutting tools. They are ideal for processing graphite, metal matrix composites (MMC), high-silicon aluminum alloys, and many other highly abrasive materials.
General-Purpose PVD Coating
General-purpose PVD coatings enhance tool hardness and elevate oxidation temperature. They are suitable for high-speed steel cutting tools and forming tools, resulting in improved machining performance.
Chromium Nitride Coating
Chromium nitride coating, abbreviated as CrN coating, has excellent anti-bonding properties. It is an ideal choice for applications prone to chip buildup. This coating enhances the performance of high-speed steel tools, cemented carbide tools, and forming tools.
Zirconium Nitride Coating
Zirconium nitride coating, abbreviated as ZrN coating, is an anti-adhesive coating without titanium or chromium. It is suitable for processing aluminum, copper, and titanium.
Titanium Aluminum Nitride / Aluminum Titanium Nitride Coating
Titanium aluminum nitride/aluminum titanium nitride (TiAlN/AlTiN) coatings can extend a high-temperature tool’s lifetime by incorporating an aluminum oxide layer. These coatings are particularly suitable for dry or semi-dry cutting of cemented carbide tools.
| Comparison of Various Coatings | ||||
| Types of coating | Color | hardness (HV) | coefficient of friction | Oxidation temperature(℃） |
| TiN | Golden | 2000 | 0.4 | 500 |
| TiCN | Blue-Purple | 2700 | 0.3 | 400 |
| TiAIN | Black-Purple | 2800 | 0.3 | 850 |
| CrN | Gray | 1800 | 0.25 | 700 |
| Diamond | Black | 9000 | 0.15 | 600 |
| ZrN | Dark Purple | 2500 | 0.4 | 800 |
How to choose the right CNC machine tool
Choosing the right cutter for your machining project, you need to identify the machining requirements such as understanding the materials of the workpieces and the types of operations you will perform. Here are some tips for choosing the right CNC cutter.
The Material Of Tool
Take the information we have listed above as a reference, high-speed steel is one of the best options of tools. However, If you need a hard tool, you can consider a cemented ceramide tool.
Coating Of Tool
Using coatings like titanium nitride improves the tool’s lifespan. But you need to balance the cost.
Machining Process
According to the types of CNC machine tools listed above, choose the right type of tool for your project according to the machining process you need to use such as CNC turning milling, or drilling.
Work with CNC machining shop – KUSLA
At KUSLA, we almost have all kinds of CNC machine tools stored in our shop. We can meet different kinds of requirements for the parts that need to be machined. Kusla can be your one-stop shop for every CNC machining project, we offer various types of CNC machining services, including milling, turning, drilling, EDM, etc. not only prototype CNC machining but also low-volume CNC machining projects, and you can be sure to get high-quality production parts.
FAQ
What is the most common material used for CNC machine tools?
Carbon Steel and High-Speed Steel are the most common materials used for CNC machine tools because they have good wear resistance and are suitable for most of the commonly used metals such as aluminum, titanium, brass, stainless steel, and plastics.
What are the differences between CNC milling tools and CNC drilling tools?
The main difference between CNC milling tools and CNC drilling tools is that they are used for different functions. CNC milling tools are used for cutting the shapes of parts and CNC drilling tools are used to create holes on the parts. So these functions make them have different tool structures and materials.
