Speeds are in Surface Feet per Minute, are specified for High-Speed Steel drill bits, and are approximate for normal drilling operations.
Speeds should be halved when using Carbon Steel bits, and can be doubled for Carbide bits. Use coolant judiciously.
For Milling operations speeds may be increased by 50%. Lathe turning speeds may be increased by 100%.
The best rule of thumb for proper cutting speed is the color of the chip (when cutting steels). Using a high-speed steel drill bit the chips should never be turning brown or blue. Straw colored chips indicate that you are on the maximum edge of the cutting speed for your cutting conditions. When using Carbide bits, chip colors can range from amber to blue, but never black. A dark purple color will indicate that you are on the maximum edge of your cutting conditions.