I. Introduction In various CNC systems, drilling programs are given in the form of drilling cycles. However, different companies' CNC systems generally define the same drilling cycle differently. Below, I will use three of the world's most well-known CNC systems as examples to detail their definition formats for drilling cycles and provide illustrations. These three CNC systems are: the NUM 760F from SCHNEMER ELEIC (France), the SINUMERIK 810D from SIEMENS (Germany), and the ACRAMATIC 2100E from CINCINNATI (USA). II. Definition of Drilling Cycles Hole machining cycles include various forms such as standard drilling, center drilling, deep drilling, and boring. This article uses standard drilling as an example. 1. NUM 760F CNC system G81X..Y..ER..Z..F.. X..Y.. X ..Y ..Z.. G80 X..Y..Z.. Where G81: Drilling cycle command x.., Y..: Coordinates of the hole center on the XY plane z..: Coordinates of the hole bottom ER..: Value of the safety plane, which is valid for all statements in the same cycle F..: Feed rate in mm/min G80: Cancel drilling cycle command, where x, Y, and z values ​​are the coordinates of the tool retraction point 2. SINUMERIK 810D CNC system CYCLE81 ​​(RTP, RFP, SDIS, DP, DPR) Where CYCLE81: Drilling cycle command RTP: Retraction plane (absolute coordinate value) RFP: Reference plane (absolute coordinate value) SDIS: Safety plane (relative distance, no sign) DP: Final drilling depth (absolute coordinate value of hole bottom) DPR: Final drilling depth relative to the reference plane (no sign) Notes: RFP and RTP: Generally, the values ​​of the reference plane (RFP) and the retraction plane (RTP) are different. In the same cycle, the retraction plane is set higher than the reference plane; therefore, the distance between the retraction plane and the hole bottom is greater than the distance between the reference plane and the hole bottom. SDIS: The safety plane (SDIS) is the relative distance to the reference plane; its direction is automatically determined by the drilling cycle. DP and DPR: Drilling depth can be defined using either DP or DPR. If both DP and DPR are defined in the program statements, and the depths defined by the two are different, then the depth value is determined by DPR. At this time, the system displays the following information in the prompt line: "Depth: C(1Hesp∞ ds to value for relative depth. 3. ACRAMATIC 2100E CNC system G81 X..Y..Z..R..W..F.. X..Y..W.. Where X.., Y..: x and Y coordinate values ​​of the hole center z..: drilling depth (distance relative to R) R..: drilling plane position (parallel to the XY plane), modal W..: retraction distance relative to the drilling plane, non-modal III. Example Illustration The above describes the specific definitions of drilling instructions for three CNC systems: NUM 760F, SINUMERIK 81OD, and ACRAMATIC 2100E. Below, I will give a simple example to illustrate that a workpiece as shown in the figure needs to be drilled with multiple holes, and the program zero point is shown in the figure. The drilling programs in the above three CNC systems are as follows. 1. NUM 760F CNC system % 100 N2 M 1OM41 N4 D1M3S1300 N6 M8 N8 G90 Nl0 G0OX30Y0Z17OBOC0 N12 G01X3OYOZ125Fl50O N14 6；81Z99F'200 Nl6 ER 125 N18 X15Y25．981 N20 X一15 22 X一3OY0 N24 X一15Y一25．981 N25 X15 N26 G8O Z160I）0 N28 M 2 2． SINUMERIK 810D CNC System%_N_100_MPF N2 T1D1 N4 M6 N8 G90（ 4 N10 M3S1300 N12 M7 N14 G71 N16 G0X30Y0Z5O N18 MCALL CYCLE81 ​​(10, -15, 20, 6) N20 HOLES2 (0, 0, 30, 0, 6) N22 MCALL N24 M2 Here, MCALL and HOLES2 (CPA, CPO, RAD, STAL, INDA, NUM) instructions are used. These are two very important instructions for drilling cycles in the SINUMERIK CNC system. MCALL is a modal subroutine call, and HOLES2 drills holes distributed on a circle. These will not be discussed in detail here. 3. ACRAMATIC 21+E CNC System: 100 (pGM, NAME = 100.PTP) N2 TlM6 N4 M3S1300 N6 M8 N8 G7lG90 NlO X3OYOZ50F2ooO Nl2 G81X3OYOZ-6R-15W 2OF2OO Nl4 Xl5Y25.981W 20 N16 X-15Y25.981W 20 N18 X-30Y0W 20 N20 X-15Y-25.981W 20 N22 X15Y-25.981 N24 G1Z5OF15oo N26 M 2 IV. Conclusion In programming CNC machine tools and machining centers, it is essential not only to be familiar with the usage of various machining instructions and cycles, but also to be adept at comparing the same machining instructions and cycles from different types of CNC systems, identifying their similarities and differences. This ensures that, given the large variety of CNC systems in the company, the numerous machining instructions are not confused, reducing program error rates, saving program debugging time, and ultimately improving production efficiency.