The G87 Back Boring cycle is used in CNC machining to create precise bores on the back side of a workpiece. This cycle is particularly useful for operations where traditional boring from the front is not possible due to part geometry or setup constraints.
Usage Format
The typical format for a G87 Back Boring cycle is as follows:
G87 X_ Y_ Z_ R_ P_ Q_ F_ L_;
Where:
- X and Y are the final bore position coordinates.
- Z is the final bore depth.
- R is the position above the hole where the boring tool waits before the operation.
- P is the dwell time at the bottom of the bore.
- Q is the amount to retract for chip breaking.
- F is the feed rate.
- L is the number of repeats for the cycle.
Explanation
The G87 cycle begins by moving the boring tool to the R position above the programmed X and Y coordinates. The tool then advances at the specified feed rate F to the Z depth. If a dwell time P is set, the tool will pause at the bottom of the bore. The tool retracts by the Q amount for chip breaking, then returns to the Z depth to continue the boring process. This cycle repeats L times if specified.
Example
Here’s a text diagram and an example of the G87 cycle in action:
(Starting position)
|
| R
| |
| | Q
| | |
| Z | |
| | | |
| | Q |
| | | |
| R | |
| | | |
+---X---Y
In this example, the tool will bore a hole at coordinates X100, Y50 to a depth of Z-25, with a retract distance of Q2 for chip breaking, and a dwell time of P1 second at the bottom of the bore.
G87 X100 Y50 Z-25 R5 P1 Q2 F10 L2;
This command will execute the back boring cycle twice at the specified location, creating a precise bore on the back side of the workpiece.