Chatter

Background

Chatter is one the most common issues in machining. However, finding the proper resolution, can be difficult to track down. The main disadvantage in troubleshooting chatter, is that the catalyst can be mechanical, tooling, programming, coolant, etc. Below, we will cover some of the more common causes that you can watch out for.

Check you Tooling for Wear

Reason: Tool wear

Tool wear is an unavoidable aspect of machining, no matter what kind of machine you are running. As a rule of thumb, always check your tooling before inserting it into the machine. Worn edges, chipped corners, and thermal cracking are common signs of a need to change up your tooling.

Click here to learn more about tool wear, and how to avoid it.

Inspect for Lack of Rigidity

Toolholders

Proper tool holding is a basic, yet, vastly overlooked key to machining. Using proper fitting collets, tool holders, chucks, etc, along with choking up as much as possible on your tool, will give you the most rigid set up as possible. Rigidity in your tooling, gives your tool its best chance at performing to its maximum ability. A common error is ER collets not seating properly. Below is a helpful graphic, that shows the correct alignment of the collet system.

Work Holding

Work Holding plays a similar role to toolholding. Holding as much of your workpiece as possible, through whatever means you are using (vises, clamps, chuck, collets), gives you the most possible rigidity. As stated previously having the most rigidity possible, allows your tool the best chance the perform at peak performance.

Chip Load/Toolpath

In conjunction with all listed solutions above, proper tool selection and running the correct technical specs, can make or break your production time and part quality. Always refer to the manufacturers recommendations for specific materials when running parts. In conjunction with proper tool selection and proper technical specs being used, using the proper toolpathing to distribute the cutting pressure on the cutter properly, is key to long tool life, as well as a quality finish. Utilizing High Efficiency Milling, and other newer cutting techniques, can help best utilize your tooling, and improve performance.

Drawbar Washer Stack

The washer stack on top of your drawbar should be periodically checked for cracks in the washers, as well as making sure the correct amount of washers are present from install. Damaged or missing washers have been known to cause chatter. It is also recommended that the stack be replaced once a year.

Power Draw Bar Pressure Deficiency

If you have a power drawbar, we recommend at least 90 PSI to obtain the proper amount of tool holding force in the spindle.

Z-Axis Gib

Please reference Mill Gib/AC Bearing Adjustment and Backlash Compensation - PCNC 770 for guidance on the adjustment process.

X or Y-Axis Gib

If you have chatter in a straight line move in one axis, and chatter is present. Vet out all other factors first. If all else fails, a gib in the opposite gib from the direction you are running, could be loose, causing chatter. For example: Straight line tool path in X chatters - check for Y axis gib.