12 Methods to Reduce Cutting Vibration on CNC Milling Machines

12 Methods to Reduce Cutting Vibration on CNC Milling Machines

Vibration and tool tremors are common problems encountered during machining, resulting in chatter marks on the workpiece surface, high rework rates, and scrap rates. 

Yaogong products and solutions (CNC Boring Milling Machining Center, CNC Gantry Machining Center, Heavy-duty Lathe, Horizontal Machining Center, CNC Vertical Machining Center, CNC Turning & Milling Machine, CNC Grinding Machine, Special Machine) are meticulously designed, and we can develop customized automation solutions to meet the specific requirements of different scenarios and projects. 

Let's summarize 12 methods to reduce cutting vibration in CNC milling machines.

1. Use sharp inserts to reduce cutting forces on CNC milling machines. Indexable inserts are divided into coated and uncoated inserts. Uncoated inserts are generally sharper than coated inserts because if an insert is coated, the cutting edge must undergo an ER (Extended Edge) treatment. A sharp cutting edge will affect the adhesion strength of the coating at the cutting edge.

2. When the depth of cut is constant, using a small tool tip radius can undoubtedly reduce cutting forces, especially radial cutting forces. Radial cutting forces are the main cause of vibration in slender tools or workpieces, whether in impact cutting or milling. At the same depth of cut, the larger the tool tip radius, the greater the tendency for slender tool shanks to vibrate.

3. When the depth of cut is selectable, avoid setting the depth of cut equal to the tool tip radius. 4. For keying with slender cutting tools or turning the outer diameter of slender shafts, using a tool with a 90° principal cutting edge angle is beneficial for vibration reduction. Whether turning a slender shaft with an outer diameter tool or turning a keyed hole with a slender cutting tool, a tool with a 90° principal cutting edge angle always generates the smallest radial cutting force. At the same time, the axial force generated by the cutting edge of the insert is the largest.

5. For slender end mills, round insert end mills are most effective for vibration reduction. Unlike split cutters, the closer the principal cutting edge angle is to 90°, the greater the radial cutting force and the greater the vibration of the cutting tool. Therefore, in face milling of deep cavity molds on CNC milling machines, a 45° principal cutting edge angle end mill is usually selected. If the depth of cut is less than 1mm, round insert end mills or ball end mills are often used.

6. When using slender end mills to mill deep cavities on CNC milling machines, plunge milling is often used. Plunge milling is when the tool enters axially like a drill bit. When milling deep cavities... Typically, the overhang of a long end mill is greater than three times the diameter of the tool holder. We recommend using axial feed for plunge milling. However, end mill inserts have a certain width of radial cutting edge. Tool suppliers provide technical data demonstrating the maximum depth of cut for this tool during plunge milling.

7. In milling thin-walled workpieces, vibration originates entirely from the workpiece itself; these are called box-shaped or bowl-shaped parts. Since the vibration originates from the workpiece, improving workpiece clamping is the primary focus when milling these parts.

8. In internal boring, a smaller insert profile angle is better. This results in a larger secondary lead angle, a smaller contact area between the secondary cutting edge and the machined surface, making it less likely for chatter to convert into vibration. The chance of chip extrusion from the secondary cutting edge is also smaller.

9. Using a face mill with sparse teeth and unequal pitch can reduce milling vibration. Here, "teeth" refers to the insert. For face mills of the same diameter (e.g., 100mm). If their three cutting factors are equal, then a cutter head with 5 inserts will definitely produce 50% less milling force than a cutter head with 10 inserts.

10. Use inserts with a positive rake angle and a large clearance angle, coupled with a light chip breaker. Such inserts have the smallest cutting wedge angle in filing or milling, resulting in a lighter cut.

11. Adjust cutting parameters. Adjusting cutting parameters may only be effective when cutting vibration is not severe. General adjustment methods are as follows: reduce the rotational speed of the tool or workpiece, decrease the depth of cut, and increase the feed rate per revolution of the tool or the milling cutter. If vibration occurs during internal thread turning, the feed steps to complete the thread turning can be reduced by 1-2 passes.

12. Properly plan the toolpath. Properly planning the toolpath is very important for milling. Milling is divided into climb milling and conventional milling. Traditional milling theory describes conventional milling as beneficial for reducing milling vibration, which actually refers to its ability to suppress vibration caused by lead screw backlash. Most modern milling machines are equipped with ball or roller screws. Therefore, conventional milling is not very effective for vibration reduction. Whether it is climb milling or conventional milling, as long as the direction of the milling force is consistent with the clamping direction of the workpiece, it will help eliminate vibration of bent plate parts.