Causes and Countermeasures of CNC Machining Vibration Problems

In CNC milling, vibration may occur due to the limitations of cutting tools, tool holders, machine tools, workpieces or fixtures, which will have certain adverse effects on machining accuracy, surface quality, and machining efficiency. To reduce cutting vibration, related factors need to be considered. The following is a summary for your reference.

Poorly rigid fixtures:

1) Evaluate the direction of the cutting force, provide adequate support or improve the fixture

2) Reduce the cutting force by reducing the depth of cut ap

3) Choose sparse and unequal pitch cutters with sharper cutting edges

4) Choose a geometry with a small nose radius and a small parallel land

5) Choose fine grain uncoated inserts or thin coated inserts

6) Avoid machining when the workpiece is not supported enough to resist cutting forces

Workpieces with poor axial rigidity

1) Consider using a shoulder cutter with a positive rake geometry (90° entering angle)

2) Choose inserts with L geometry

3) Reduced axial cutting forces - smaller depth of cut, smaller nose radius and parallel land

4) Select unequal tooth pitch sparse tooth milling cutter

5) Check tool wear

6) Check the runout of the tool holder

7) Improve tool clamping

Tool overhang is too long

1) Make the overhang small

2) Use unequal pitch milling cutter

3) Balance radial and axial cutting forces - 45° entering angle, large nose radius or round insert milling cutter

4) Increase the feed per tooth

5) Use light cutting insert geometry

6) Reduce the axial depth of cut af

7) Use up-cut milling in finishing

8) Use oversized cutters and adaptors with Coromant Capto® interface

9) For solid carbide end mills and interchangeable head mills, try a cutter with fewer teeth and/or a larger helix angle

Milling square shoulders with a poorly rigid spindle

1) Choose the smallest possible diameter milling cutter

2) Choose light-cutting cutters and inserts with sharp cutting edges

3) Try up milling

4) Check the spindle deflection to see if it is within the acceptable range of the machine tool

Unstable table feed

1) Try up milling

2) Tighten the feed mechanism of the machine tool: For CNC machine tools, adjust the feed screw

3) For conventional machines, adjust the locking screw or replace the ball screw

Cutting parameters

1) Reduce the cutting speed (vc)

2) Increase the feed (fz)

3) Change the depth of cut ap

poor stability

1) Shorten the overhang

2) Improve stability

Vibration in corners

1) Use large programmed fillets at lower feed rates