Preparing the CNC Program Before Machining
Before the workpiece is loaded, the machining program must be fully prepared.
For long or complex machining sequences, avoid creating G-code directly on the CNC machine to prevent unnecessary machine downtime.
Instead, use offline programming or CAM software.
Even for short programs, drafting a program sheet is recommended for review and verification.
Powering On the CNC Machine
The standard start-up process requires switching on the machine power first, followed by the CNC control system.
Certain machines feature interlock designs, meaning the CRT or display will not show data unless the main power is fully activated.
Performing Machine Referencing (Homing)
For machines equipped with incremental encoders or incremental measurement systems, referencing must be completed before operation.
This step establishes the machine’s reference point for each axis, ensuring positional accuracy for all subsequent movements.
Transferring or Inputting the CNC Program
Depending on the storage medium—tape, disk, USB, or serial communication—the program can be imported through:
- Tape reader or cassette drive
- External programming units
- RS-232 or network transfer
- Direct input via the CNC panel
For simple or one-time jobs, operators may use MDI (Manual Data Input) to enter and execute the program line by line.
Before machining, input the correct workpiece zero point, tool offsets, tool length compensation, and other related machining parameters.
Editing and Modifying the Program
If the code requires adjustments, switch the mode selector to Edit.
Use the editing keys to add, modify, or delete lines.
Refer to the machine’s programming manual to ensure compliance with valid G-code and editing rules.
Running a Dry-Run with Machine Lock
Before executing actual machining, perform a machine-lock or dry-run test.
This allows verification of tool paths, feed movements, and overall program safety without moving the machine axes.
If errors occur, revise the code accordingly and retest.
Mounting the Workpiece and Setting the Tool
Secure the workpiece on the fixture or vise.
Use incremental jog, continuous jog, or the handwheel to move the tool into position.
Set the starting point and establish the reference surface for tool length and cutter compensation.
Starting Coordinate Feed and Machining
Most CNC machines perform continuous machining directly from memory, which is more reliable than tape-based input.
Operators may adjust the feed rate using the feed override switch.
During machining, press Feed Hold to pause for inspection or measurement. Press Cycle Start to resume.
For contour milling, operators may use a pencil to trace the tool path on paper placed over the workpiece outline, making verification more intuitive.
If the CNC system includes a tool-path simulation function, use it to confirm program accuracy before cutting.
Monitoring Operation on the Display Panel
The CNC display (CRT) provides real-time information such as:
- Tool or worktable position
- Program execution status
- Machine conditions and alarms
Monitoring these indicators ensures safe, stable machining.
Saving or Outputting the Machining Program
When machining is complete, save the program in the CNC memory if it will be reused.
For longer programs, export the code to external storage such as tape, disk, USB drive, or network storage for backup and future use.
Shutting Down the CNC Machine
After all operations are complete, shut down the CNC control system first.
Then turn off the machine’s main power following the manufacturer’s recommended shutdown sequence.
English