The phrase speeds and feeds is a term of art in the field of machine tooling that refers to the parameters of a machining operation that are necessary to calculate or reference externally. The wording is derived from two commonly encountered values in machining processes, cutting speed and feed rate, but there are additional inputs that fit the .
During a machining operation, there are large forces present between the cutting edge of the tool and the workpiece, and large amounts of heat are generated by friction and deformation of the material as it is removed. If those factors are not accounted for when executing a toolpath, either manually or by a computer control system, thermal and mechanical stresses can lead to premature tool wear, loss of surface quality in the workpiece, or damage to the tool. Additionally, economic considerations typically motivate cutting operations to be performed as efficiently as possible.
Cutting speed is the relative speed at the point of contact between the cutting edge of the tool and the material of the workpiece, and is typically expressed in units of surface feet per minute (sfm) or meters per minute (m/min).
Feed rate is the rate at which the cutting tool traverses the material, and is expressed in different units depending on the context. When independent of spindle speed, the units are typically revolution (ipr) or inches per tooth (ipt).
Cutting speed (also called surface speed or simply speed) is the speed difference (relative velocity) between the cutting tool and the surface of the workpiece it is operating on. It is expressed in units of distance across the workpiece surface per unit of time, typically surface feet per minute (sfm) or meters per minute (m/min).[1] Feed rate (also often styled as a solid compound, feedrate, or called simply feed) is the relative velocity at which the cutter is advanced along the workpiece; its vector is perpendicular to the vector of cutting speed. Feed rate units depend on the motion of the tool and workpiece; when the workpiece rotates (e.g., in turning and boring), the units are almost always distance per spindle revolution (inches per revolution [in/rev or ipr] or millimeters per revolution [mm/rev]).[2] When the workpiece does not rotate (e.g., in milling), the units are typically distance per time (inches per minute [in/min or ipm] or millimeters per minute [mm/min]), although distance per revolution or per cutter tooth are also sometimes used.[2]
If variables such as cutter geometry and the rigidity of the machine tool and its tooling setup could be ideally maximized (and reduced to negligible constants), then only a lack of power (that is, kilowatts or horsepower) available to the spindle would prevent the use of the maximum possible speeds and feeds for any given workpiece material and cutter material. Of course, in reality those other variables are dynamic and not negligible, but there is still a correlation between power available and feeds and speeds employed. In practice, lack of rigidity is usually the limiting constraint.
Outside of the context of machine tooling, "speeds and feeds" can be used colloquially to refer to the technical details of a product or process.[3]