EngineerBenchCalculating drill RPM from diameter and material
For a drill diameter D in millimeters and cutting speed V in meters per minute, RPM is 1000 × V ÷ (π × D). A larger drill needs a lower RPM to keep the same speed at its outer edge. Choose the work material, enter the drill diameter, and check the calculated speed against the speeds available on your machine.
When to enter your own cutting speed
The material presets are starting values for the stated tool basis, not recommendations for every drill. Use the tool manufacturer's data for a coated, carbide, indexable, or otherwise specialized drill. Deep holes, interrupted cuts, poor support, and limited coolant may need a different process.
Feed and drilling time
Feed per revolution describes how far the drill advances in one turn. Multiplying it by RPM gives feed per minute. The drilling-time estimate covers the entered cutting travel; pecking, retracts, approach moves, and handling add time. Do not treat that estimate as a complete production cycle.
Moving from a calculated speed to a machine setting
For a 10 mm drill and a chosen cutting speed of 20 m/min, the equation gives about 637 RPM. At the same cutting speed, a 20 mm drill requires about 318 RPM. Diameter is in the denominator, so doubling diameter halves RPM. These examples use an assumed cutting speed to illustrate the relationship, not a material-specific recommendation.
A stepped-speed drill press may not offer the exact calculated RPM. Choose a setting using the tool and machine guidance, then use the surface-speed mode to see what that setting actually produces. If a drilling feed of 0.1 mm per revolution is used at 600 RPM, feed is 60 mm/min. A 30 mm cutting travel would take half a minute at that steady feed. The drill point, breakthrough, peck cycles, and approach allowance can change the travel or elapsed time needed. Record the selected machine speed rather than retaining an unattainable theoretical RPM in a job setup sheet.
Formula
RPM = 1000Vc/(πD). Feed = RPM × feed/rev; milling multiplies chip load by flute count.