Tips to Prevent Coining


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



When a direction change is programmed as a straight linear motion (G01) into another straight linear motion, the sudden direction change can cause the tool to leave coining marks on the surface of the part. Use a toolpath that has smooth transitions on change of direction. Consider using your CAM system's constant-engagement toolpath options.

Feedrates may be too high to cut smoothly through the programmed direction changes. Reduce the feederate.

Tool Selection

Cutting tools with sharp corners [1] can leave coining marks on the surface being machined.

Change to a tool that has a corner radius or a corner chamfer [2].


The FIR (Finite Impulse Response) filter is a Haas software feature that uses the servo motor to achieve higher acceleration rates with smoother transitions, reduced cycle times, and reduced vibration from machine motion. FIR filters come standard and are always active on all Haas mills with M17.00 and newer software and Haas lathes with L10.00 and newer software.

On mills, Haas software has a notch filter feature that adjusts the acceleration rates of the axes to compensate for the machine's vibration. The amount of adjustment is based on machine frame size. The notch filters are available on mills with M18.00 and newer software.

Contact your Haas Factory Outlet to check that these filters are on and correctly set for your machine.

Machine accessories like the chip conveyor, chip auger or, Side Mount Tool Changer (SMTC) can introduce vibration into the machine causing coining to appear. Before you start the finish cut, turn off the chip auger and chip conveyor; and pre-stage the next tool.


Vibrations from external sources can transfer into the machined finish and appear as coining.

Before you start the finish cut, stop nearby forklift traffic, crane operation, and welding operations.

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.