Calculate cutting data for CNC milling: correctly classify speed, feed and spindle power

Suitable cutting data are an important basis for a stable CNC milling process. Speed and feed must not be considered in isolation. Tool diameter, number of cutting edges, material, intervention ratios, delivery and the actual available spindle power work together.

The free ABEL cut data calculator supports this computational classification. It not only calculates the speed and feed speed, but also shows the thickness of the machining, the volume of the time, the cutting force, the power requirement and the torque. The determined requirement can then be compared with the inputed spindle data via the integrated spindle test.

What are cutting data for CNC milling?

Cut data refers to the technical quantities with which a machining process is described and interpreted computationally. The most well-known values include the cutting speed vc, the speed n, the tooth feed fz and the feed speed vf.

The cutting speed describes the relative speed at the tool edge. It and the tool diameter result in the required speed:

N = (vc × 1,000) / (π × D)

The feed speed then results from speed, cutting edge number and tooth feed:

Vf = n × z × fz

These relationships already show why individual values should not be changed independently of each other. A higher speed also leads to a higher feed with unchanged tooth feed and the same number of cutting edges. If only the speed is increased without adjusting the feed accordingly, the load on the cutting edge changes.

What values does the ABEL CNC cut data calculator calculate?

The ABEL cutting data calculator for milling machining and spindle testing maps several levels of a milling process:

Speed: derived from cutting speed and tool diameter

Feed speed: derived from speed, tooth feed and cutting edge number

Medium chipping thickness: for classifying the actual chip formation in the selected intervention conditions

Time span volume: as a calculated quantity for the material delay per unit of time

Specific cutting force and main cutting force: to estimate the occurring load

Machining power and required motor power: taking into account the input efficiency

Cutting torque and required motor torque: for the assessment of the torque requirement at the operating point

The calculator goes beyond a simple speed feed calculator. It combines the classic cutting data calculation with a computational consideration of the spindle utilization.

Calculate cutting data: a simplified example

Assume that a milling cutter with a diameter of 6 mm and two cutting edges is to be used with a cutting speed of 300 m/min. Calculatingly, this results in a speed of around 15,900 rpm. With a tooth feed of 0.04 mm, the feed speed is around 1,270 mm/min.

This example shows the mathematical relationship. However, these four values are not yet sufficient for the actual processing. The milling cutter geometry, the cantilever length, tool holder, axial and radial delivery, workpiece tension, cooling or lubrication as well as the dynamics of the machine and spindle also influence the result.

Why the tension thickness says more than the tooth feed alone

The tooth feed is a starting value. The actual resulting chipping thickness additionally depends on the intervention of the tool. Especially in the case of small radial deliveries, the average chipping thickness can differ significantly from the entered tooth feed.

This is relevant, for example, in dynamic milling or trochoidal strategies. If this effect is not taken into account, the cutting edge can be loaded less than intended. Instead of cutting cleanly, the tool can rub harder. This can promote heat development, wear and an unfavorable surface.

Spindle test: Compare power and torque at the operating point

A spindle does not have the same available power and the same available torque at every speed. Therefore, a mere indication of the rated power is not always sufficient for the assessment of a concrete milling process.

In the spindle test, the input spindle parameters are compared to the computationally determined demand. The calculator shows how the process is classified in relation to the available power and the available torque.

This assessment is for technical guidance. The actual spindle characteristic, the operating limits and the specifications of the spindle manufacturer remain decisive. Even short-term load states, tool condition, concentricity, voltage and real material properties cannot be fully represented by a calculation model.

How to use the cut data calculator sensibly

Select material group: The stored characteristic values form the calculation basis.

Enter tool data: Diameter, edge number, and geometry must match the tool actually used.

Set cutting dates: Cutting speed and tooth feed should come from reliable tool manufacturer information or documented empirical values.

Supplementing delivery: Axial and radial delivery influence material removement, force and power requirements.

Look at results together: speed, feed, torque thickness, power, power and torque only together result in a meaningful picture.

Check spindle data: Rated power, rated speed and, if applicable, rated torque must match the actual spindle.

Process validated in a controlled manner: calculation results are initial values. The actual processing must be observed under safe conditions and adjusted step by step.

Common errors in cutting data calculation

Increase speed without adjusting the feed accordingly

Incorrectly enter the number of cuts or effective tool diameter

Apply manufacturer values of another tool or geometry

Do not select radial and axial delivery appropriate to the machining strategy

Only look at the spindle power and neglect the torque requirement

Do not take into account the concentricity, extension length and stability of the tension

Understand computational results as binding approval for the real process

For the secure workpiece tension, the ABEL clamping force calculator can be used in addition. There, too, the result is a mathematical orientation and does not replace a professional interpretation of the concrete clamping situation.

Which CNC machine is suitable for high speeds and small tools?

In micro-processing and small tool diameters, high required speeds often occur due to the small diameter. At the same time, concentricity, dynamic behavior, tool recording and process stability are particularly relevant.

ABEL develops compact 3 axis CNC milling machines and 5 axis CNC milling machines for different machining tasks. Which spindle, axle configuration and equipment is suitable depends on the material, component, tool, required result and planned process.

Frequently asked questions about the CNC cutting data calculator

Is the ABEL editing data calculator free of charge?

Yes. The online version can be used free of charge in the browser. On the computer page there are also download options for a Windows and a mobile version.

Can the calculator automatically specify cutting values for each tool?

The computer processes the entered tool and process data as well as stored material characteristics. Resilient starting values for cutting speed and tooth feed should preferably come from the information of the respective tool manufacturer or from documented practical experience.

What is the difference between tooth feed and feed speed?

The tooth feed describes the computational feed per cutting edge. The feed speed describes the total feed per minute and results from tooth feed, cutting number and speed.

Why does the computer check both power and torque?

A process can appear inconspicuous with regard to performance and nevertheless have a relevant torque requirement at the operating point. Both sizes are important for the technical classification of a spindle.

Does the calculation replace a milling test?

No. The computer supports the technical estimation. Tool manufacturer information, machine and spindle data, a professional process design and controlled practical validation remain necessary.

Calculate cutting data online

With the ABEL CNC Calculator, essential process variables can be viewed together and compared with the input spindle data. This creates a comprehensible computational basis for the further interpretation of the process.

Open the free CNC cutting data calculator now

Are you planning a concrete machining task or would you like to classify the requirements for a compact CNC milling machine? Via the contact page you can send us the most important information about material, workpiece, tools and desired processing.

Note: All calculation results are for technical guidance. They do not replace professional process design, machine or tool manufacturer information, tests or the assessment by qualified personnel.