Check out this great tool from Norseman Drills web site
While different drilling conditions make it impossible to develop any rigid rules for feeds and speeds. Norseman has put together some great charts on their website that can serve as “rules of thumb” to determine proper feeds and speeds for drilling ferrous materials.
They also provide a calculator where you can enter variables such as tool diameter and cutting speed to determine feed rates and cut times.
CLICK HERE to open the Feed and Speed Calculator
NOTE: Varying conditions can easily require adjustments.
• Feed equals .001″ per revolution for every 1/16″ of drill diameter, plus or minus .001″ on the total.
• Speed equals 80 surface feet per minute in 100 Brinell hardness material and the speed should be reduced 10 surface feet per minute for each additional 50 points Brinell hardness.
• Feed and speed rates should be reduced up to 45-50‰ when drilling holes deeper than 4 drill diameters.
Feeds and Speeds – Formulas:
R.P.M.= (3.8197 / Drill Diameter) x S.F.M.
S.F.M.= 0.2618 x Drill Diameter x R.P.M.
I.P.M.= I.P.R. (feed) x R.P.M. (speed)
Machine Time (seconds) = (60 x Feed minus Stroke) / I.P.M.