G21 Code For Milling

G21 CODE FOR MILLING WITH FANUC CONTROLLER

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The G21 code is basically used to convert dimension to millimeter(mm).
G20 Code For Milling

APPLICATION:-

• In CNC Milling machine, we use both G21 and G20 Code. These codes are used to declare the dimension in our program. Because in our program we never consider dimensional units after X... Y... Z... co-ordinates. So this G21 and G20 Codes are used to declare dimensions to our program. 
• As per the G21 Code, this Code is used to declare that our program works upon the millimeter dimension. All the X... Y... Z... coordinates are works upon millimeter dimension.
• Now if the G21 Code is applied in the safety block of the CNC program. Then the whole program is working upon millimeter dimension.
• In case, you want to change dimensional unit at any block from millimeter to inches. Then you just have to write G20 code in front of the desired block.

Learn About G81 Code For Milling

G21 Code

EXAMPLE-1:- 

In this example, we are going to add G21 Code in the safety block of the program. 

G-CODE for Milling

G17G21G54G90

MO6T01

M08

M03S1000

G00X0Y0F40

G01Z-5

G01X40

Y50

Y60

X70

Y80

Z10

G28X0Y0Z0

M05

M09

M30

M-CODE for Milling

So, in this program, we add G21 code in the safety block of the program. so the G21 code is applicable for all the coordinate units. Now all the units in this program work upon the millimeter unit. 

EXAMPLE-2:-

Now, in this Program, we are going to change the dimension from millimeter to inches.

G17G21G54G90

MO6T01

M08

M03S1000

G00X0Y0F40

G01Z-5

G20G01X40

Y50

Y60

X70

Y80

G21Z10

G28X0Y0Z0

M05

M09

M30

Lots Of Drawings For CNC Machining Practice.. Click Here

So as we can see the G21 code is written in the safety block. So that the millimeter dimension is applicable upon all the program. But I just add G20 code in front of G01 code before starting the cutting procedure. Now the cutting procedure works upon the inches dimensions as we required. 

So, in this way, we can use both the G21 Code and G20 Code in a single program.