Lathe cutting tools are tools that you can use with a CNC lathe to produce turned parts, remove excess material, and finally make the desired shape. They are an important part of CNC machining. Therefore, understanding the components of a turning tool, and the role of each part, is very important for choosing the right turning tool.
This article will introduce in detail the various components of CNC turning tools and their main roles in the turning process. After reading this article, you will have a complete understanding of the construction of turning tools. Let’s dive right in.
The picture above shows us clearly the various parts of the turning tool. Let’s take a look at a few key parts and what role they play in cutting.
Ⅰ. Effect of rake angle
The increase of the rake angle makes the cutting edge sharp, the chip flow resistance is small, the friction force is small, and the cutting deformation is small, so the cutting force and cutting power are small, the cutting temperature is low, the tool wear is small, and the machined surface quality is high. However, too large rake angle reduces the rigidity and strength of the tool, the heat is not easy to dissipate, the tool wear and tear are serious, and the tool life is low. When determining the rake angle of the tool, the selection should be considered according to the processing conditions.
Next we give a guidance for the choice of bigger rake angle and smaller rake angle for you:
|Small rake angle||1. When machining brittle and hard materials|
2. When roughing and interrupted cutting
|Big rake angle||1. When machining plastic and soft materials|
2. When finishing
Ⅱ. Effects of clearance angle
The main function of the clearance angle in machining is to reduce the friction between the tool flank and the machined surface. When the rake angle is fixed, the increase of the relief angle can increase the sharpness of the cutting edge, the cutting force is reduced, and the friction is reduced, so the machined surface quality is high; however, the excessive relief angle reduces the strength of the cutting edge, poor heat dissipation, and wear The amount is large, so the tool life is reduced.
The principle of rear angle selection is: in the case of less severe friction, choose a smaller rear angle.
Here we give a guidance for the choice of bigger clearance angle and smaller clearance angle for you:
|Small clearance angle||1. In order to increase nose strength when roughing|
2. When roughing and interrupted cutting
|Big clearance angle||1. In order to reduce friction when finishing|
2. When machining materials easy to be hardened
Ⅲ. Effects of inclined angle
The positive or negative edge inclination determines the direction of chip discharge, and also affects the strength and impact resistance of the tool tip.
As shown in the figure a. below, when the edge inclination angle is negative, that is, the tool tip is at the lowest point relative to the bottom plane of the turning tool, and the chips flow to the machined surface of the workpiece.
Reducing the main declination angle can improve the strength of the tool, the heat dissipation condition is good, and the roughness of the machined surface is small. This is because when the entering angle is small, the cutting width is long, so the force per unit cutting edge length is small. At the same time, reducing the entering angle can improve the life of the tool.
Usually, when turning slender shafts and stepped shafts, choose a 90° entering angle; when turning on the outer circle, end face and chamfering, choose a 45° entering angle.
Increase the main declination angle, the radial component force is reduced, the cutting is smooth, the cutting thickness is increased, and the chip breaking performance is good.
Below we have a guidance for the choice of bigger approach angle and smaller approach angle for you:
|Small approach angle||For those materials with high intensity, high hardness and hardened layer on the surface|
|Big approach angle||When rigidity of the machine is not enough|
The secondary declination angle is the main angle that affects the surface roughness, and its size also affects the tool strength. Too small secondary declination will increase the friction between the back of the secondary and the machined surface, causing vibration.
The selection principle of the secondary declination angle is that a smaller secondary declination angle should be selected under the conditions of rough machining or without affecting friction and vibration; a larger secondary declination angle can be selected during finishing.
Ⅵ. Nose radius
The radius of the tool nose arc has a great influence on the strength of the tool nose and the roughness of the machined surface.
The radius of the tool nose arc is large, the strength of the cutting edge increases, and the wear of the front and flank surfaces of the tool can be reduced to some extent. However, when the radius of the tool nose arc is too large, the radial cutting force increases, and vibration is easily generated, which affects the machining accuracy and the surface roughness of the workpiece.
Below we can see the difference between a bigger nose radius and a smaller nose radius:
|Small nose radius||Finishing at small cutting depth|
Machining parts such as slender shaft
When the rigidity of the machine is not enough
|Big nose radius||When roughing/When machining hard materials(intermittent cutting)|
When the rigidity of the machine is good
Take TNMG1604 CNC turning insert as an example: when you need to finish at smaller cutting depth, you may choose TNMG160404, and you may use TNMG160408 or TNMG160412 when for roughing.
If you’re new to CNC turning and don’t know much about the components of a turning tool, choosing the right type of tool to use with your lathe can be problematic. However, instead of worrying about how much you have to know, hire the services of professionals in this field. At UKO, we have engineers and R&D teams with many years of CNC machining experience who understand the different types of lathe cutting tools and their applications. By choosing us, you gain years of experience and an attitude towards quality delivery. Please contact us. We are always at your service!