How is the cutting speed when CNC milling calculated?

Cutting speed is defined as the speed on the outer edge of the instrument when it is cutting. The cutting speed depends mainly on the type of material you are cutting and the type of cutting tool you are using. The hardness of the machining material is greatly related to the proposed cutting speed. The harder the working material, the slower the cutting speed. The softer the working material, the faster the proposed cutting speed. If two cutting tools of different sizes rotate at the same rotation rate per minute (RPM), then the larger tool has a greater surface speed. Surface speed, surface cutting step and surface area are all directly related.

Considering the hardness of the machining material, the cutting speed can be indicated as follows:

Aluminum > Lead > Iron > Steel

Judging by the hardness of the cutting tool, the cutting speed can be indicated as follows:

Carbon > Carbide > > Wind Steel

Cutting speed spreadsheet

Material type	Cutting Speed (SFM)
Low Carbon Steel	40-140
Medium Carbon Steel	70-120
High Carbon Steel	65-100
Free-machining Steel	100-150
Stainless Steel, C1 302, 304	60
Stainless Steel, C1 310, 316	70
Stainless Steel, C1 410	100
Stainless Steel, C1 416	140
Stainless Steel, C1 17-4, pH	50
Alloy Steel, SAE 4130, 4140	70
Alloy Steel, SAE 4030	90
Tool Steel	40-70
Cast Iron–Regular	80-120
Cast Iron–Hard	5-30
Gray Cast Iron	50-80
Aluminum Alloys	300-400
Nickel Alloy, Monel 400	40-60
Nickel Alloy, Monel K500	30-60
Nickel Alloy, Inconel	5-10
Cobalt Base Alloys	5-10
Titanium Alloy	20-60
Unalloyed Titanium	35-55
Copper	100-500
Bronze–Regular	90-150
Bronze–Hard	30-70
Zirconium	70-90
Brass and Aluminum	200-350
Silicon Free Non-Metallics	100-300
Silicon Containing Non-Metallics	30-70

Spindle Speed

When calculating the SFM cutting speed for a given material and tool is determined, the spindle can be calculated because this value depends on the cutting speed and knife diameter. We have the formula below:

RPM = (CS X 4) / D, in which:

• RPM = Revolutions per minute: Number of spins per minute.
• CS = Cutter speed in SFM: Cutting speed in SFM.
• D = Tool Diameter inches: Instrument diameter in inches.

Speed of purification in milling machine

The speed of purification can be defined as the distance calculated in mm/min when moving working in a milling machine. The progress rate is capable of operating independently of the rotational speed of the spindle, in order to ensure maneuverability as well as a reasonable arrangement so that when the mill operates with different details the adjustment will become easier.

A number of factors affect the speed of purification of the milling machine:

1. The depth and width of the cut.
2. Types of cutters.
3. Sharpness of the cutting knife.
4. Embryonic materials.
5. The strength and uniformity of the embryo.
6. Requires fine processing.
7. The necessary accuracy.
8. The strength and hardness of the machine, the device holds and sets up the instrument.

Knife progression speed in milling machine

Knife progression speed is the amount of material that should be removed by each tooth of the knife as it rotates and enters the machining area.

As the cutting knife enters the machining area, each tooth of the cutter enters the machining area in equal amounts creating chips of equal thickness.

Chip thickness or machining salary per tooth, along with the number of teeth in the cutting knife, form the basis for determining the speed of knife progression.

The ideal knife progression rate for milling is measured in inches per minute (IPM) and is calculated according to this formula:

IPM = F X N X X RPM in which:

• IPM = Feed rate in inches per minute: Knife progress rate per inch per minute
• F = Feed per tooth: The amount of processing per tooth
• N = Number of teeth: Number of teeth
• RPM = Revolutions per minute: Rotation every minute

The conclusion

As such, we can already better understand how to calculate the cutting speed when milling CNC properly. To be able to accurately process the types of materials and product details you need to train a lot to be able to form a habitual mindset to operate correctly on CNC machines.

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