What is chatter, and what do I do about it?

Chatter is a screeching or singing sound that occurs when a machining operation hits its resonant frequency. It’s unpleasant to the ears and is bad for your part and the machine. Vibrations can create wavy patterns on your part (poor surface finish), the waviness results in wider chips that are harder to break (shortens tool life), and the vibrations increase wear on the spindle (shortens machine life).

One potential solution is to change the spindle speed or feed rate of the machine, either by speeding it up or slowing it down. This change in speed could alter the frequency enough so that it doesn’t resonate. Another option is to choose a cutting piece with fewer flutes, or to change how far the tool sticks out of the chuck to alter the rigidity of the system. Think of chatter in terms of a beam bending equation-more energy into the system increases likelihood of chatter. Listen here.