8 Basic CNC Programming
8.4 NC Codes
98
Last movement command in
program
The last block of a program should move the tool back to the starting
position. The tool will then be in position to start cutting another part.
8.3.
REVIEWING AN NC PROGRAM
Once an NC program has been written, it must be checked carefully before the first part is machined.
Errors in an NC program can cause machine damage and injury to the operator.
Follow this procedure to check an NC program.
Procedure: Reviewing an NC Program
1.
Double-check all program blocks against your coding sheet to locate and correct typographical errors.
2.
Look for the typical coding error that places two X, Y, or Z codes in the same block.
3.
Be sure that all required coordinates have been written into appropriate blocks.
4.
Verify the part program to discover any program errors.
5.
Run the part program without mounting stock in the milling center to see if the tool movements are
logical.
0
.
8.4.
NC CODES
NC codes are divided according to category. Some categories consist of one code only (single category
type), while other categories include a large number of different codes (multiple category type).
This table lists all code categories. Information on all codes is presented in the sections referenced.
Info Table: G Code Categories
Code
Function
Type of Category
Section
Page
%
Incremental Arc Centers (Fanuc)
Single
$
Absolute Arc Centers
Single
\
Skip
Single
/
Optional skip
Single
F
Feed rate in inches per minute, with
G04, the number of seconds to dwell
Single
G
Preparatory codes
Multiple
H
Input and output selection number
Single
I
Arc center, X axis dimension (circular
interpolation)
Single
J
Arc center, Y axis dimension (circular
interpolation)
Single
K
Arc center, Z axis dimension (circular
interpolation)
Single
