How to Estimate Machining Time in CNC Milling

Estimating machining time is essential for planning production and quoting jobs.

For simple cases, you can estimate machining time from path length and feed rate. This is useful for early planning and for comparing different strategies in CAM.

The basic formula

For a straight line toolpath, machining time is:

time (min) = path length (mm) / feed rate (mm/min)
    

You can automate this calculation with the Machining Time Estimator.

Factors that increase machining time

• Acceleration and deceleration of axes
• Changes in tool engagement along the path
• Z-moves, retracts and linking moves
• Tool changes, probing cycles and pauses

While CAM simulation provides the most accurate results, this quick formula is great for early estimates and for comparing the relative impact of different feeds and strategies.