CNC MACHINING
CALCULATORS
FEEDS & SPEEDS

Feed rate is the linear velocity at which the cutting tool advances through or along the workpiece. In milling, it is commonly measured in millimeters per minute (mm/min) or inches per minute (IPM). In turning and drilling, feed is often expressed as feed per revolution (mm/rev or IPR).

Milling feed rate is calculated using the formula: Feed Rate = Spindle Speed (RPM) × Number of Flutes (Z) × Chip Load per Tooth (fz). For example, a 4-flute end mill running at 3,000 RPM with a chip load of 0.05 mm/tooth produces a feed rate of 3,000 × 4 × 0.05 = 600 mm/min.

Chip load here means nominal feed per tooth: fz = F / (n × z). Actual chip thickness varies with cutter geometry and engagement. Use the cutting tool supplier’s recommendations for your material and setup.

Feed rate is the tool’s linear travel speed, such as 600 mm/min. Feed per tooth is the advance per cutting tooth, such as 0.05 mm/tooth. They are related by F = n × z × fz; actual chip thickness also depends on cutter engagement.

Feed per revolution (fn) is the linear distance the tool advances for one complete 360-degree rotation of the spindle. It is the primary feed parameter in lathe turning and drilling, where multi-tooth chip distribution does not apply in the same manner as milling.

In metric units: RPM = (1,000 × Vc) / (π × Tool Diameter in mm). In imperial units: RPM = (12 × SFM) / (π × Tool Diameter in inches), commonly approximated as (SFM × 3.82) / Diameter.

SFM is the linear surface cutting speed at the outer perimeter of the cutting tool in feet per minute. It reflects how fast the cutting edge shears the material and determines cutting zone temperatures and tool wear rates.

Yes, in milling. Because each cutting flute shears a chip during each revolution, doubling the number of flutes doubles the total material advancement rate at the same chip load and RPM (Feed Rate = RPM × Flutes × Chip Load).

Material removal rate is the volume removed per unit of time. For rectangular milling, Q = ap × ae × F. With depths in mm and feed in mm/min, divide by 1000 to obtain cm³/min. With inches and inches/min, the result is in³/min.

In 90° peripheral milling, radial engagement below half the cutter diameter reduces maximum chip thickness below the programmed feed per tooth. Compensation raises the feed to approach the target thickness. This model does not apply to ball-nose or high-feed cutters. Always check tool and machine limits.

The calculated feed rate is a mathematical starting point. You must evaluate your specific machine rigidity, spindle horsepower, workholding rigidity, tool overhang, workpiece hardness, and coolant capabilities before applying cutting parameters.

Yes. You can switch between Metric (mm, mm/min, m/min, cm³/min) and Imperial (in, IPM, SFM, in³/min) at any time. Entered values are converted accurately without loss of engineering context.