Balance Impact on Spindle Life

​I hesitate to post this, but there has been a lot of questions about balancing and this is interesting information. This is from a 12 year old defense industry presentation. I could not find our original research documents, so don't bust me with questions about the test parameters. Be assured that we would have never presented unsubstantiated data to the DoD. Also, no need to mention the damage to your spindle that chatter causes

"In our test example, every ONE HOUR of use of an UNBALANCED tool assembly (G20 vs. G5) reduces the life of the spindle by FOUR HOURS. 

In other words, use unbalanced tools for three months and you will have to change or rebuild your spindle, the most expensive component on the machine, one year sooner. Plus, days or weeks of downtime."