What is Chatter?


Under certain conditions, a cutting tool or workpiece begins to vibrate. These vibrations begin to feed back on themselves and resonate, transferring into the machined surface and causing a wavy finish. This surface finish flaw is commonly referred to as “chatter”. Chatter is a complex phenomenon, and its causes and solutions are not always intuitive—nearly every aspect of your application can play a role in chatter.

How does Chatter “Feed on Itself and Resonate”?

When chatter begins, it leaves a wavy surface behind. A second cut through this surface, for example by the next flute, insert, or tooth on the tool, causes a variable load on the cutting edge. The vibration from this cut spreads to the next cut, amplifying and intensifying the vibration with each successive cut.

How Can I Correct Chatter?

Look at your application as a whole when you investigate a chatter issue. Generally, there are three aspects of the application that you can control to stop chatter:

  • The Program: Feeds, Speeds, depth- and width-of-cut and Toolpaths
  • Tooling: Tool Geometry, Material, Size, Number of Flutes
  • Workholding: Connection to the Table, Connection to the Part

Ideally, you would have optimal solutions for all of these aspects, but in the real world, you may have to make compromises—for example, maybe you have a deep pocket to machine and so a tool is longer than ideal, or your workholding cannot grip a thin-walled part as firmly as the application demands. In these cases, to prevent chatter, you need to change the parts of the application that you do have control over: For example: to compromise for the long tool, maybe you would back off your depth-and width-of cut; for the light-grip workholding, you might choose tooling with geometry that reduces cutting forces.

Why is it Important to Correct Chatter?

Aside from the noise and bad surface finish, chatter causes accuracy issues. It can also shorten the service life of your tooling, your workholding, and the machine tool itself.

More Information

Refer to the chatter prevention and troubleshooting documents on the Haas Customer Resource Center.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.