QianJiu machining

Thread milling programming

Release time:May 14, 2019 Visits:

Key words: G02/G03;macro program;screw thread milling

Thread milling is a new process for thread machining since the development of CNC systems. Compared with the traditional thread processing method, it has great advantages in machining precision and machining efficiency, and is not restricted by the thread structure and thread rotation during machining. A thread milling cutter can process a variety of different directions of rotation, External thread.

1 circular interpolation command G02/G03 format




G02/G03: round/reverse circle. In the arc coordinate plane, the positive direction of the unspecified coordinate axis (G17 plane: Z axis; G18 plane: Y axis; G19 plane: X axis) is observed in the negative direction, the clockwise arc is G02; and the counterclockwise circle The arc is G03. R: arc radius. When the arc center angle is less than 180°, R is a positive value; when the arc center angle is greater than or equal to 180°, R is a negative value; the full circle cannot use the R command, only I, J, K instruction. I, J, K: Applicable to any arc, which represents the displacement of the center of the arc relative to the starting point of the arc in the X, Y and Z directions.

2 thread milling machining program

2.1 Milling programming format for single pitch threads G17G02X_Y_I_J_Z_F_

2.2 Milling programming of multiple pitch threads

2.2.1 General programming format for multiple pitch threads (B1, B2, Bn are shown in Figure 2).

G17 G02 I_ J_ ZB1F_;

G17 G02 I_ J_ ZB2F_;

G17 G02 I_ J_ ZBnF_;

2.2.2 The parameter meaning of the multi-pitch thread parameterized programming format program is shown in Figure 3.

3 thread milling processing parametric programming example

3.1 Preparation before processing The internal thread shown in Figure 3, blank initial hole: Φ39; blank: 100mmX100mmX20mm nylon block, bottom hole: Φ40.376; processing equipment: HCK714D machining center; clamping method: flat jaw clamp; used tool :I13-Single-blade thread milling cutter, radius of gyration 13.5, I11-45° chamfering cutter, T12 镗 boring tool.

3.2 Processing Step 1 Invert the 45° angle - T11 knife. 2 boring Φ40.376 ―T12 knife. 3 milling thread - T13 knife (three times processing: roughing, semi-finishing, finishing). Unilateral machining allowance = (42-40.376) / 2 = 0.812. The first machining allowance was 0.512, rough machining. The second machining allowance is 0.20, semi-finished. The third machining allowance is 0.10, finishing.

3.3 Threading program

3.3.1 Main program:

01000; (program name)

G21G80G69G40G17G49; (Metric, cancel fixed cycle cancel rotation cancel radius compensation, XY plane, cancel length compensation)

T11M06; (for the 11th chamfering knife)

G54G90G00G43Z100H1; (establish the workpiece coordinate system and quickly locate it at Z100)

G00X0Y0M13S400; (quick positioning to zero point, cutting fluid open spindle forward rotation 400 revolutions per minute)

G99G81X0Y0Z-1.5R5F50; (threaded hole chamfer)

G00G80Z100; (cancel the fixed cycle and lift the knife)

M05; (spindle stop)


T12M06; (for the 12th sickle)


G00 X0 Y0 M13 S600;

G99 G76 X0 Y0 Z-22 Q0.3 R5 F60; (pupil)

G00 G80 Z100;



T13 M06 (for single-blade thread milling cutter)

G00 G54 G90 G43 Z100 H13;

G00 X0 Y0 M13 S1600;


G65 P2000 A20.7 B-20 C13.5 E1.0 H1.5; (roughing, as shown in Figure 5)

G65 P2000 A20.9 B-20 C13.5 E1.0 H1.5: (semi-finishing, Figure 6)

G65 P2000 A21.0 B-20 C13.5 E1.0 H1.5; (finishing, as shown in Figure 7)


3.3.2 Macro program

O2000 (macro program name)

#5= #1- #3;(Thread milling cutter radius of gyration)

G00 X#5;


G01 Z#8 F200;

WHILE [#8 GT #2] DO1 (macro program conditional statement)

#8=#8 - #11; (assigned in the Z-axis direction)

G02 I-#5 Z#8 F400; (XYZ three-axis linkage milling thread)

END 1; (conditional statement terminated)

G01 X[#5-3];

G00 Z30;


  4 Conclusion 

In the above, we introduced the use of G02/G03 circular interpolation command and the application of macro program to write milling CNC machining programs, and their different programming methods. Through the example, the internal thread is processed on an aluminum block. In the actual production process, the two programming methods should be used correctly and flexibly according to the processing characteristics and requirements of the workpiece.

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