Programming of CNC Machines. Ken Evans
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The operator may input small programs via the keypad at the control. The size of the program is limited to 10 lines on the control that is described in this book and is determined by the parameter setting from the manufacturer. It is an excellent method of executing simple commands like tool changes, controlling the spindle r/min and its rotation direction, etc. To enter the MDI mode of operations follow these steps:
1. Press the MDI button on the operator panel.
2. Press the PROGRAM function key.
3. Enter the desired program number preceded by the letter address O.
4. Enter the data to be executed by using the methods described later in PROGRAM EDITING FUNCTIONS.
As soon as the program number is entered, you can begin to enter program data. If a program number is not input, the control assumes O0000, and the data may be entered. Each block ends with end of block (EOB) character (;) so that individual blocks of information can be kept separately. For example: N1G50S1000;
5. Press the EOB function key to insert the semicolon at the end of each line.
6. Press the INSERT edit key.
7. Press CYCLE START to execute the program information.
If a typographical error is made while entering a given block, you can eliminate the error by pressing the CAN key to CANCEL the error and then reenter the correct value.
The MDI program may be executed just as with automatic operation and the same control functions apply except that an M30 (tape rewind) command does not return the control to the program head instead M99 is used to perform this function. Please refer to the machine tool manufacturer manual for specific instructions.
Erasure of an entire program created in MDI mode may be accomplished as follows:
1. Use the alphanumeric keypad to enter the address O.
2. Press the DELETE key on the MDI panel.
The same result may be accomplished by pressing the RESET key.
Also the program will be erased when execution of the last block of the program is completed by single–block operation.
To perform an individual MDI operation, use the methods described above. For the control described here use the display screen shown in Figure 34.
Example 1:
1. Turn on the spindle at 500 RPM in the clockwise direction.
2. Key in the following command:
3. S500M03
4. EOB
5. INPUT
6. CYCLE START
Figure 34 Program Screen in MDI Mode
Example 2:
Follow these directions to position tool number 5 to the active position on the turret (or to install tool 5 into the spindle on a milling machine).
Key in the following command:
1. T0500 (or T5M06 for a mill)
2. EOB
3. INPUT
4. CYCLE START
The codes listed along the bottom of the display pictured in Figure 34 are G-Codes that are active upon start up of the machine called defaults. They are also reinstated upon pressing of the RESET key.
MEASURING WORK OFFSETS, TURNING CENTER
It is necessary to establish a relationship between the machine coordinate system and the workpiece coordinate system. The following steps are necessary to input the measured values for the workpiece zero to the controls Work Coordinates offset page.
Measure the Z Axis Work Coordinate
1. Manually position the cutting tool and make a cut on the face of the workpiece.
2. Without moving the Z axis, stop the spindle and move the tool away from the part in X-axis direction.
3. Measure the distance along the Z axis from cut surface to the desired zero point.
4. Press the WORK soft key to display the WORK COORDINATES display screen.
5. Position the cursor to the desired Workpiece offset to be set.
6. Use the letter address key Z to select the axis to be measured
7. Use the value of the measurement taken to input the Z axis Work Coordinate
8. Press the MEASUR soft key.
The Work Coordinate for the Z axis will be input.
Measure the X Axis Work Coordinate
1. Manually position the cutting tool and make a cut along Z axis to create a diameter on the workpiece.
2. Without moving the X axis, stop the spindle and move the tool away from the part in Z axis direction.
3. Measure the diameter you just cut on the workpiece.
4. Use the value of the measurement taken to input the X axis Work Coordinate (enter the diameter).
5. Follow the same procedure for setting the Z axis Work Coordinate value as stated in steps six and seven above.
The Work Coordinate for the X axis will be input.
MEASURING WORK COORDINATE OFFSETS, MACHINING CENTER
Following is the procedure for setting the Work Offsets for each workpiece coordinate system G54 to G59. When the values are known you can:
1. Press the OFFSET/SETTING function key.
2. Press the WORK soft key.
The WORK COORDINATES setting screen is displayed as shown in the Figure 35. There are two display screens needed to handle the six offsets G54 to G59. To display a desired page, follow either of these two methods:
1. Press the PAGE up or PAGE down keys until the desired offset is shown.