Parameter Restoration and Debugging o

Parameter Restoration and Debugging of FANUC 18M CNC System for Machining Centers

1. Common Issues During Equipment Debugging

In 2003, our machining workshop purchased a JET-40H vertical machining center, equipped with a CNCT-40JF worktable from Genlong Precision Machinery Co., Ltd. The machining center uses the FANUC 18M control system, which is a 5-axis vertical machining center (X, Y, Z, A, C axes) with an RS232 interface for PC connection.

Due to staffing changes and incomplete handover, the post-commissioning data backup for this machining center was lost. Recently, due to an operator error, all programs and parameters were wiped. Only the original factory backup data was available. While most parameters could be reused, some needed adjustment for normal machining.

2. Debugging Steps

The CNC memory card stores the following data: CNC parameters, PMC parameters, pitch error compensation values, custom macro variable values, tool compensation values, and part programs (machining and macro programs). Among them, CNC and PMC parameters are core to the machine’s proper operation and axis coordination.

Data should be exported from the control unit to an I/O device while the system is functioning correctly. We used PCIN software version 4.2, set to COM1, baud rate 4800, 7 data bits, and 2 stop bits.

2.1 CNC Parameter Input

CNC parameters are crucial and typically imported first. The machine must be in Emergency Stop mode to input data. Steps:

Press the OFFSET/SETTING key multiple times, then press softkey [SETTING] to access the setting screen.
Set “PARAMETER WRITE = 1”.
Press the SYSTEM key, enter the parameter screen.
Set parameter 0103 for baud rate (e.g., 11 = 9600 baud).
Use RS232 for serial transfer. Press [READ], then [EXEC] to begin.
Once done, power cycle the machine.

2.2 PMC Parameter Input

PMC parameters (PLC ladder logic) control logic, timing, and counting. Steps:

Set Emergency Stop, disable protection key (KEY4 = 1).
Go to [SETTING], confirm “PARAMETER WRITE = 1”.
Press SYSTEM, go to [PMC] > [PMCPRM] > [KEEPRL].
On K900/K17, set first bit to “1” (Input: 0000001 INPUT).
Open I/O menu, set CHANNEL = 1, DEVICE = FDCAS (floppy).
Press [READ], then [EXEC] to import PMC parameters.

2.3 Pitch Compensation Input

Each machine’s lead screw pitch is not perfectly consistent due to manufacturing tolerances. Therefore, pitch error compensation is essential for precision.

Steps:

Release Emergency Stop, enter EDIT mode.
Set “PARAMETER WRITE = 1”.
Press PROG, then [PRGRM] to view programs.
Press [OPRT] > [F SRH], enter 3, press [EXEC] to select pitch file.
Press SYSTEM > [PARAM] > [PITCH] to open pitch screen.
Press [OPRT] > [READ] > [EXEC] to input data.
After input, reset “PARAMETER WRITE = 0”.

2.4 Macro Program Input

Macro programs are stored in No.9000–9999. These are protected and will raise alarms if transferred without proper settings.

To allow transfer:

Ensure PASSWD = 0, modify parameter NO3202#4 to unprotect.
Enter EDIT mode, disable protection (KEY2 = 1).
Press PROG > [PRGRM], then [OPRT].
Input macro program number (e.g., O9000), press [READ] > [EXEC].
After input, switch to MEMORY mode, run the program to apply variables.
Press OFFSET/SETTING > [MACRO], then search 9000 to confirm values are set.

2.5 Machining Center Calibration and Commissioning

After parameters and macros are restored, further calibration is required:

(1) Mechanical Home Position Adjustment:

In manual mode, move X, Y, Z axes to desired home positions.
Modify parameter 1815#5#4 for each axis to “1”.
Power off/on to finalize origin setup.

(2) Backlash Compensation:

Fix a dial indicator base on a static point.
Rotate handwheel (×10 scale) in one direction and note value.
Rotate in the reverse direction until table first moves, record handwheel rotation.
Multiply by 10 and input into parameter 1851 for that axis.

(3) Work Coordinate System Origin Calibration:

Macro programs rely on the work coordinate system (WCS).
Carefully calibrate the WCS zero point to ensure program accuracy.