Part Program

A part program is a series of coded instruction that are needed to the movement of the machine tools and the ON/OFF controls of auxiliary functions such like spindle rotation and coolant for producing a part. The fundamental commands of coded instructions are M- codes, G-codes, T-function, and F-function. Any part program, simple or complexes, is coded from these instructions. A word is the fundamental building unit of the part program. It always begins with an address followed though a numeric value, for example.

G01   -  Linear interpolation mode

X5.0   - X-dimension (5.0 in + X direction)

F15.0  - Feed rate at 15 inches per minute

The coded instructions are formed of letters, numbers, and symbol and are arranged in the format of functional words and blocks, for example

N5 G00 X2.0 Y3.0 S1000 M3

Here                

N5 = sequence number

G00 = rapid traverse mode

X2.0 = X-coordinate (2.0′′)

Y3.0 = Y-coordinate (3.0′′)

S1000 = spindle rate (1000 rpm)

M3 = spindle on (Clockwise direction)

There are four methods of generating CNC part programs, such as:

• Manual programming method,
• Computer-assisted programming method,
• Conversational programming method, and
• CAD/CAM programming method.

In the manual programming method, standard M-codes, G-codes, T-function, and F-function are utilized to create the part program block-by-block. A computer program permits the programmer to pre-define part-geometry, tool-path movements and auxiliary functions, in computer-assisted programming method. Most of modern CNC controls provide conversational programming function to permits part-programmers to interact along with the control for producing part programs. CAD/CAM programming method basically consists of three components CAD, CAM and post processor. CAD creates part geometry; CAM utilizes that part geometry to generate tool paths. At last, the post-processors convert the toolpaths to CNC part programs for specific CNC machine.