Feed refers to the depth of penetration of the tooth into the material being cut. For cost effective cutting, you want to remove as much material as possible as quickly as possible by using as high a feed rate/pressure as the machine can handle. However, feed will be limited by the machinability of the material being cut and blade life expectancy.
A deeper feed results in a lower shear plane angle. Cutting may be faster, but blade life will be reduced dramatically. Light feed will increase the shear plane angle, but increase cost per cut. How can you tell if you are using the right feed rate? Examine the chips and evaluate their shape and color.
If you see very fine or pulverized chips, this indicates the blade feed rate should be increased.
If you see thick, heavy or blue-colored chips, your blade is being overloaded.
Loosely coiled chips indicates ideal cutting conditions.