01
Sharp inserts can be used to decrease the cutting force of CNC milling machines.
Pinned inserts come in coated and uncoated varieties. Uncoated inserts are typically sharper than coated inserts because if the inserts are coated, the edges must be passivated (ER treated) first.
This is because a sharp edge can weaken the adhesion strength of the coating to the edge.
02
When cutting to a specific depth, using a small nose radius can significantly reduce cutting forces, especially radial forces.
Radial cutting force is the main cause of vibrations in tools or workpieces with thin shanks.
Regardless of whether it is grinding or milling, the greater the radius of the tip arc, the greater the tendency of the thin rods to vibrate at the same cutting depth.
03
When selecting the cutting depth, it should be avoided that the cutting depth is equal to the arc radius of the tool tip.
04
For cutting keys with thin knife shanks or external turning of thin shafts, using a tool with a 90° primary inclination is beneficial in reducing vibration.
Whether it is an external turning tool rotating a slender shaft or a keyhole in a slender tool holder, a 90° tool with the main offset angle generates the lowest radial cutting force while producing the highest axial force at the edge of the blade. .
05
For cutters with thin shanks, cutters with round inserts are more effective in reducing vibration.
Milling cutters are the opposite of shaker cutters.
The closer the main rake angle is to 90°, the greater the radial cutting force and the more the rod will vibrate.
06
When CNC milling machines use slender shank end mills to mill deep cavities, plunge milling is often employed. Insert milling refers to the axial advancement of a drill-like tool when milling deep cavities.
For a long bar with an overhang greater than 3 times its diameter, it is recommended to use insertion milling with axial feed.
However, the end mill insert has a radial cutting edge of a certain width.
The tool supplier has technical data indicating the maximum tool width when using insert milling.
07
When milling thin-walled parts, the cause of vibrations comes exclusively from the workpiece, also known as the box or bowl part.
Since vibration originates from the part itself, the main focus when handling milling of such parts is to improve the clamping of the part.
08
When drilling internal holes, the smaller the angle of the blade edge, the better.
This occurs because the secondary slope becomes too large, reducing the chatter contact area between the secondary cutting edge and the surface being machined, making it difficult for the chatter to transform into vibration.
Furthermore, the probability of the secondary cutting edge compressing a chip is also low.
09
If a face mill employs a cutter with uneven pitch and sparse teeth, milling vibrations can be reduced.
The term “tooth” refers to the blade.
For example, a 100mm diameter face mill with a 5-blade cutter should generate 50% less milling force compared to a 10-blade cutter if both cut all three elements equally.
10
Use the large front and back corners of the blade with a light chipbreaker groove.
These inserts have the smallest cutting angle during filing or milling, resulting in a lighter and faster cut.
11
Adjust the cutting parameters, which can only be effective if the cutting vibration is not severe.
The general adjustment method involves reducing the rotational speed of the tool or workpiece, decreasing the depth of cut, and increasing the feed of the tool by rotation or abusive tooth displacement.
In case of vibration during internal thread turning, the feed rate to complete thread turning can be reduced by 1 or 2 cuts.
12
Streamline the blade process path. Proper process routing is very important for milling operations.
There is a distinction between straight and reverse milling, and traditional milling theory suggests that reverse milling reduces milling vibration. However, this is only effective in suppressing vibrations generated by screw play.
With most modern milling machines equipped with ball screws or rollers, the damping effect of reverse milling is minimal.
Whether it is down milling or up milling, as long as the direction of the milling force is consistent with the clamping direction of the workpiece, it can help eliminate vibration in bent plate parts.
