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Drilling Feeds and Speeds Planning Worksheet

Most drilling programs start with a guess carried over from the last job. This worksheet makes the arithmetic visible: enter diameter, surface speed, feed per revolution and depth, and it returns RPM, feed rate and drilling time.

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Spindle speed (RPM)	Feed rate (in/min)	Drill time per part (sec)
1,019	7.1301	20.6168
1,222	6.1115	48.5967
1,019	3.0558	25.771
2,292	27.5018	9.163

Total drilling time per part (sec)

104.1476

Total drilling time (minutes)

1.7358

Starting values only. Surface speeds and feeds in the example rows are typical starting points for solid carbide or coated HSS drills in rigid setups; use the tool maker's data for your drill. Time adds 0.3 x diameter for the drill point and excludes rapids, peck retracts and dwell.

Feed planned cycle times into routings

Optional: ask how planned cycle times could update routings and quotes in your ERP.

Optional. The tool and every export work without this. No spam.

How to use the worksheet

Add one row per hole size, set material and the surface speed in SFM from your tooling data, then enter feed in inches per revolution and the depth. The sheet calculates spindle speed as SFM x 3.82 divided by diameter, feed rate as RPM x feed per revolution, and the time to drill all holes of that size. Totals show drilling time per part so you can compare to the cycle target.

Use the drill maker's SFM range as the start
Reduce feed for deep holes and add pecking
Add 0.3 x diameter for the point
Keep rapids and peck retracts separate

The formulas

Spindle speed in RPM equals 12 x SFM divided by pi x diameter in inches, which is about 3.82 x SFM divided by diameter. Feed rate in inches per minute equals RPM x feed per revolution. Time in cut equals depth plus the point allowance divided by feed rate. Metric users can convert: RPM = 1000 x m/min divided by pi x diameter in mm.

Reading the output

Check that RPM is within the machine and tool holder limit, and that feed rate in inches per minute is not so high that the machine cannot hold it through acceleration on shallow holes. Small drills at the calculated RPM may exceed spindle capability, in which case lower the RPM and use the actual feed per revolution to recompute. Compare times by hole size to see which operation dominates the cycle.

Common mistakes

Do not apply the same SFM to every material in a family; stainless and titanium need far less than mild steel. Do not forget through-spindle coolant or pecking on holes deeper than about three diameters. Avoid entering depth that excludes the point for blind holes where drill depth matters, and watch for programs that dwell at the bottom, which adds time the worksheet does not show.

Frequently Asked Questions

How do I convert SFM to RPM for a drill?

Use RPM = SFM x 3.82 / diameter in inches. For a 0.375 inch drill at 100 SFM, RPM is about 1019. The worksheet does this for every row and rounds for display.

What feed per revolution should I use?

Use the drill manufacturer's recommendation for diameter and material. As a rough guide, feed per revolution rises with diameter, so small drills use a few thousandths and half inch drills about 0.010 or more depending on material and drill type.

Does the time include peck cycles?

No. It is a straight-through feed time plus point allowance. Peck cycles add retract and rapid moves; add that time separately or increase the allowance in your own program estimate.

Can I use metric units?

Yes, if you change the formula constants. Easier is to convert diameter to inches and surface speed to SFM (1 m/min is about 3.28 SFM) before entering, then convert feed rate back.

If you want planned cycle times to flow into routings and quotes inside your ERP, Netray can help connect them.

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