Mill Tips to Prevent Chatter


Consider the overall job when you have a problem with chatter. Chatter always comes down to these aspects of the application:


Compromises required in one aspect of the job will require adjustments to the other aspects of the job.



Toolpaths with slotting and large corner engagement can cause chatter at a given speed/feed combination. Note how tool engagement increases through the internal corner [1] and in a slot cut [2].

Toolpath Types

With a conventional toolpath, cutting forces increase as tool engagement increases with the direction changes.

Constant engagement toolpaths do not require adjustments to speeds and feeds through direction changes.

Tool Selection

Tool Selection - Tool Length

If the cut chatters and reducing the tool length is practical, reduce the tool length. A 10% reduction in the length-to-diameter ratio results in a 25% increase in tool stiffness.

Unless absolutely necessary, the tool should not be more than 3 times longer than it is wide.

Tool Length and Deep Pockets

Deep pockets require deviation from the normal length-to-diameter ratio for tools. Lower the cutting load with program adjustments: reduce the depth-of-cut, the width-of-cut, feed, or change to a constant-engagement toolpath.

Tool Types

Use the highest-performance tool possible, ideally with variable helix and cutting angles. High-performance tooling uses tool geometry designed to dampen the vibrations that cause chatter.


Workholding Example:

Fragile workholding, a long, skinny part, overhangs, etc.—Lower the cutting load through adjustments to the tool selection or program. Stiffen the workholding with supports if possible.

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.