Types of Lathe Tools Used in CNC Turning
If you know enough about CNC machining and want to learn more about cutting tools, you may find this guide helpful.
CNC turning is a well-known process of shaping components from workpieces of various types of materials. The essential point of CNC turning is the cutting tools utilized. However, readers are often given incomplete and confusing information about them, resulting in difficulty purchasing suitable ones for a particular purpose.
Read below about all existing cutting tools of lathe machines, their distinctive purposes, recommendations on choosing ones, and answers to some frequent questions.
The most significant distinctive feature of all lathe cutting tools is that they are fed to a spinning workpiece. Thus, they form symmetrical, from an axial perspective, designs in a cylindrical shape.
All lathe cutting instruments are single-point ones and are held by tool holders. The shaping outcomes depend on the angle they feed to a workpiece, cutting speed, feed rate, and depth.
Classification of Lathe Cutting Tools
One of the non-obvious ways to categorize lathe cutting tools is to divide them into two major groups. The first of which are ones that are fed at a certain angle for some operations and can be either right-hand or left-hand intended tools. Others are neutral tools and are fed perpendicularly to a workpiece.
Some tools can belong to both groups. You can see examples in the image and read descriptions of major groups of tools below.
- Roughing tools. They are designed to cut off the outside layer of the material of a workpiece to the approximately correct size.
- Turning/finishing tools. Being different in the matter of precision, turning and finishing tools are needed to remove material from the workpiece directly, making a sufficient surface with lower or higher accuracy, respectively.
- Facing tools. They are used to cut flat surfaces on a workpiece.
- Grooving tools. Such instruments are intended to cut external or internal grooves and other machining operations such as cutting slots.
- Forming tools. They are designed flat or circular and used to form a shape with the required dimensions.
- Thread cutting tools. They are necessary to create screw threads in a workpiece. It moves across the piece linearly, taking chips off the workpiece with each pass.
- Undercutting tools. Such instruments create recessed surfaces that are inaccessible using a straight tool.
- Boring tools. Their purpose is to produce holes by either detaching material or pushing it to one side, as a needle does, without removing.
- Chamfering tools. Such instruments are one of the most common ones and are used to eliminate sharp edges leaving a sloped surface.
- Reaming tools. They are used to enlarge an existing hole to achieve a new size and shape if needed.
- Parting tools. Such narrow-bladed tools are used in turning for cutting a piece in two.
How to Select Lathe Machine Tools
- A particular design intended to be shaped by a tool being selected.
- Speed of spinning a workpiece during the machining (some metal may not be sustainable enough).
- The angle at which a cutting tool is intended to be fed to a workpiece (neutral, left-hand, right-hand).
- Type of material a workpiece is made of (type of metal of a cutting tool is to be adjusted accordingly).
- Physical parameters of a tool, which include insert geometry of a tool, insert grade, insert shape, lead angle, and insert nose radius.
A cutting tool will suit a particular intended purpose and effectively function if chosen appropriately.
1. How to reduce vibration in cutting tools?
It is recommended to revise the CNC turning machine’s settings, so they are more optimal without compromising the quality of finished components.
2. Why do cutting tools need to bend?
The reasons why cutting tools bend or are deformed in any other ways are the following.
- Bending strength and toughness are low compared to the material being cut.
- Excessive force.
- High stresses and temperature.
- The hardness of a tool is not enough.
- Low pressure resistance of a tool.
- Tool wear is inappropriate.
3. What are two types of threading cutting tools?
Taps and dies are the cutting tools intended to create screw threads. The first ones are intended to form the female portion of the mating pair, while the second ones cut the male portion.
You can find additional information in the “Classification of Lathe Cutting Tools” section in the above text.
4. How to remove rust from cutting tools
It is not recommended to remove corrosion that mechanical methods cannot treat with chemical acids as it may damage processing accuracy. The acceptable ways to remove rust are immersion cleaning and wiping cleaning.
- Immersion cleaning. Add the professional cleaning stock solution into the plastic tank and heat it to 40-50°C with an electric heater (further maintenance is recommended but not obligatory). Soak a cutting tool into the tank. To improve the efficiency, agitate the bath by circulation pump or equal manual movement with any tool made of the neutral material – glass. Wait until the rust is completely dissolved, remove a tool from the tank, and rinse it. After natural drying and dehydrating, apply rustproof.
- Wiping and cleaning. Wipe repeatedly with a rag and a cleaning solution. After wiping, dry it with hot air or naturally dehydrate, and apply anti-rust oil.
5. What type of steel are lathe cutting tools?
Here is the list of all the materials lathe cutting tools can be made of.
- Carbon Steels
- High-speed steel (HSS)
- Cast cobalt alloys
- Ceramics, such as Alumina and Silicon Nitride
- Cubic Boron Nitride
It can also be noted that whisker reinforcement and coatings are applied to modify cutting tools made of some of the mentioned materials.
6. Why are coatings used on cutting tools?
Coatings are 2 -15 micro-m thick layers of material, including titanium nitride, titanium carbide, and aluminum oxide. Coatings are frequently applied, especially to carbide tools, to improve a cutting instrument’s life and/or to enable higher cutting speeds. Thus, coated tips typically live 10 times longer than uncoated ones.
7. What process is used most to coat cutting tools?
Techniques used for applying coatings are the following:
- Chemical vapor deposition (CVD). It is the use of thermally induced chemical reactions at the surface of a heated substrate with reagents supplied in gaseous form.
- Plasma enhanced CVD (PECVD). This method is the form of CVD with the use of plasma deposition to provide energy for the reaction enabling it to be conducted at a lower temperature.
- Physical vapor deposition (PVD). It is the use of a metal vapor that can be deposited on electrically conductive materials in a vacuum chamber.
Each cutting tool has its specific purpose, and all of them can be classified by the angle they are fed to a workpiece.
To select a sufficient cutting tool is vital to consider machining parameters and materials both a tool and workpieces are made of.