What is the simple CYCLE TIME calculation formula on machines?

Absolutely!

All the information is available. But, and this is important, there is a lot more going on than the simple formulas used to derive feedrate and spindle rpm can account for.

In the spirit of full disclosure, you can find the simple formulas in a lot of places, but I'll link to Wikipedia. These formulas accept as inputs surface speed and tool diameter to calculate spindle rpm, and they accept number of flutes, spindle rpm, and chipload to calculate feedrate.

Seems pretty simple, so where is the problem?

We've already seen one fly in the ointment in the form of radial chip thinning. Those formulas on Wikipedia don't account for chip thinning, so anytime you're cutting less than half the diameter of the cutter as your stepover or cut width, they're wrong. The thinner the cut, the more they're wrong, and ultimately they will be very wrong.

So, you'll need to go research the formulas for chip thinning so you can add them too. You'll also want to find a large table of materials, with chiploads and surface speeds. Ideally your table is large enough to be a materials database that considers not just broad classes of materials, but individual alloys as well as the condition of the alloy, and adjusts the figures accordingly. You will want to scale back your figures if you are slotting. In fact, you want to adjust based on how wide the cut is as well as how deep. There are manufacturer's tables out there to help you do that, it's just one more step to add to your process.

Speaking of steps, this stuff all adds up, and eventually, you have an awful lot of steps to be punching numbers into a calculator while rabidly flipping back and forth to look at various charts. I recommend using an Excel spreadsheet. In fact, that's how my G-Wizard feeds and speeds software started out, but I'll warn you, you will outgrow Excel if you keep adding bells and whistles like I did. More on that below.