I searched all over and cannot find my answer. I am a total newbie - just got my machine running this weekend. Its a RF-45 by the way

I used the G-Wizard and set my feeds and speed accordingly and am wrecking bits faster then I can put em in there... lol

Here is how I had my last run setup.

3/16" flat end mill HSS-Co8 - 4 flutes- feed rate 6.737 - spindle speed 3,119rpm - plunge rate 1.6 - depth of cut .0188 - cutting cold rolled steel - Good Ole WD40as a lubricant.

The issue I am having is the tip turned black and wont cut no more. The run before that on a different bit turned bright orange and melted the bit.

What the heck am I doing wrong???