# Common calculation formulas for CNC precision machining

Common calculation formulas for CNC machiningI. Trigonometric Function Calculation

1.tanθ = b / a θ = tan-1b / a

2.Sinθ = b / c Cos = a / c

Calculation of cutting speed for cavity machining Vc = (π * D * S) / 1000

Vc: Linear velocity (m / min) π: Pi ratio (3.14159) D: Tool diameter (mm)

S: speed (rpm)

Example. Using a Φ25 milling cutter with Vc as (m / min) 25, find S =? Rpm

Vc = πds / 1000

25 = π * 25 * S / 1000

S = 1000 * 25 / π * 25

S = 320rpm

Third, the calculation of the cavity processing feed (F value) F = S * * * Fz

F: Feed amount (mm / min) S: Speed (rpm) Z: Number of blades Fz: (Actual feed per blade)

Example. A standard 2-blade end mill cuts the workpiece at a speed of 2000 rpm and finds the feed rate (F

Value)? (Fz = 0.25mm)

F = S ＊ Ｚ ＊ Fz

F = 2000 * 2 * 0.25

F = 1000 (mm / min)

Fourth, the calculation of residual material height

Scallop = (ae ＊ ae) / 8R

Scallop: Residual material height (mm) ae: XYpitch (mm) R Tool radius (mm)

Example. Φ20R10 finishes 2 blades, the pre-residue height is 0.002mm, what is the pitch? mm

Scallop = ae2 / 8R

0.002 = ae2 / 8 * 10

ae = 0.4mm

V. Calculation of escape hole Φ = √2R2 X, Y = D ／ 4

Φ: Escape hole diameter (mm) R Tool radius (mm) D: Tool diameter (mm)

Example. It is known that a mold cavity must be machined (see picture). CNC computer gong machining is the driving part of the CNC machine tool actuator, including the spindle drive unit, feed unit, spindle motor and feed motor. He realizes the spindle and feed drive through electric or electro-hydraulic servo system under the control of numerical control device. When several feeds are linked, processing of positioning, straight line, plane curve and space curve can be completed. Huizhou CNC machining tools for CNC milling are called CNC milling machines or CNC machining centers. A lathe that performs CNC turning is called a CNC turning center. NC machining G code can be programmed manually, but usually the machining workshop uses CAM (Computer Aided Manufacturing) software to automatically read CAD (Computer Aided Design) files and generate G code programs to control CNC machine tools. Shenzhen CNC machining is actually a CNC milling machine. It is called "CNC machining center" in Guangzhou, Jiangsu, Zhejiang and Shanghai. It is an automatic machine tool with a program control system. , (NC machine tool) is the abbreviation of Computer Numerical Control Machine Tool (Computer numerical control), which is an automatic machine tool controlled by a program. The control system can logically process the program specified by the control code or other symbolic instructions, and decode it by the computer to make the machine tool operate and process the part. Cutting of raw materials into semi-finished products by tool cutting.

The milling cutter used is & PHOTOSHOPi; 10; What is the smallest angle hole? What is the center coordinate?

Φ = √2R2

Φ = √2 * 52

Φ = 7.1 (mm)

X, Y = D / 4

X, Y = 10/4

X, Y = 2.5 mm

The center coordinates are (2.5, -2.5)

6. Calculation of reclaiming amount = (ae * ap * F) / 1000

Ｑ: Receiving amount (cm3 / min) ae: XYpitch (mm) ap: Zpitch (mm)

Example. It is known that the height of a mold must be cavity. The XYpitch of the Φ35R5 knife is 60% of the tool. Each layer is cut by 1.5mm and the feed is 2000mm / min. What is the material withdrawal of this tool?

Ｑ = (ae * ap * F) / 1000

Ｑ = 35 * 0.6 * 1.5 * 2000 ／ 1000

Ｑ = 63 cm3 / min

Seven, the calculation of the feed amount per blade Fz = hm * √ (D / ap)

Fz: Implement feed amount per blade hm: Theoretical feed amount per blade ap: Zpitch (mm)

D: Blade diameter (mm)

Example problem (assuming that depo XYpitch is 60% of the tool)

For the depoΦ35R5 cutter, cutting NAK80 material (Material) hm is 0.15mm, Z-axis cutting depth is 1.5mm, what is the feed amount per blade?

Fz = hm * √ (D ／ ap)

Fz = 0.2 * √10 / 1.5

Fz = 0.5mm

Cutting edge processing method of die edge processing depth = plate thickness-cutting edge height + drill tip (0.3D)

D represents the drilling time formula of the tool diameter drill bit T (min) = L (min) / N (rpm) * f (mm / rev)

= ΠDL / 1000vf

L: full length of drilling N: number of revolutions f: feed amount coefficient D: drill diameter v: cutting speed as shown in hole depth l full length of drill hole L then L = l + D / 3

T = L / Nf = πDL / 1000vf

Coefficient table f diameter mm feed mm / rev

1.6 ~ 3.2 0.025 ~ 0.075

3.2 ~ 6.4 0.05 ~ 0.15

6.4 ~ 12.8 0.10 ~ 0.25

12.8 ~ 25 0.175 ~ 0.375

Above 25 0.376 ~ 0.625

The calculation formula of the tube tooth is 1 inch = 25.4mm = 8 minutes 25.4 / number of teeth = pitch. For example, 25.4 / 18 = 1.414. The pitch is 5/16 wire attack horsepower (commonly known as: horse) (gun drill)

W = Md * N / 97.410

W: required power (KW)

Md: Torque (kg-cm)

N: number of revolutions (r.p.m)

The torque calculation formula is as follows:

Md = 1/20 * f * ps *

f is the feed amount mm / rev coefficient r is the drill radius race (mm)

α: Cutting resistance ratio (value obtained by comparing two numbers) ps. At small feeds, the general steel is 500 kg / m2; the general cast iron is 300 kg / m2.

Have you written down the above CNC machining formulas, the cavity machining feed and cutting volume hope to help you in your work!