I just read this study from Ryerson University by Drs. Omar Garber and Seyed Hashemi.
“The aim of this paper is to present a semi-analytical stability technique, developed to incorporate the spindle’s dynamic behavior variations in the stability lobes diagram. The change in the spindle’s dynamic behavior, also referred to as aging, is generally caused by system’s bearings wear, translated through a reduction in the system’s natural frequencies.”
Since our new SpeedCast Dashboard is an automated and interactive visualization of the stability lobe diagram, it could be used to track a spindle’s condition.
An initial baseline tap-test of a tool assembly produces a Dashboard that is used to establish the program’s speed, width and depth of cut. Periodic tap-tests of that same tool will either; 1) verify the cutting parameters are still good, or 2) expose that the parameters, likely the speed, must be adjusted to maintain stability.
If 2 is true, the user has two choices. They can slow the speed and keep running parts or have the spindle serviced. When should they pick the latter? If the speed reduction, and the impact on productivity, is small, then probably not. A quick cost per cubic inch calculation will determine if the loss in revenue will justify fixing the spindle.
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