Cycle 21 PILOT DRILLING

ISO programming

G121

Application

Use Cycle 21 PILOT DRILLING if you machine a contour and then use a tool for roughing it out which has no center-cut end mill (ISO 1641). This cycle drills a hole in the area that will be roughed out later with a cycle such as Cycle 22. Cycle 21 takes the finishing allowance for side and the finishing allowance for floor as well as the radius of the rough-out tool into account for the cutter infeed points. The cutter infeed points also serve as starting points for roughing.

Before programming the call of Cycle 21 you need to program two further cycles:

  • Cycle 14 CONTOUR or SEL CONTOUR—required by Cycle 21 PILOT DRILLING to determine the drilling position in the plane
  • Cycle 20 CONTOUR DATA—required by Cycle 21 PILOT DRILLING to determine parameters such as the hole depth and the set-up clearance

Cycle sequence

  1. The control first positions the tool in the plane (the position results from the contour that you previously defined with Cycle 14 or SEL CONTOUR, and from the information on the rough-out tool)
  2. The tool then moves at rapid traverse FMAX to set-up clearance. (specify the set-up clearance in Cycle 20 CONTOUR DATA)
  3. The tool drills from the current position to the first plunging depth at the programmed feed rate F.
  4. Then, the tool retracts at rapid traverse FMAX to the starting position and advances again to the first plunging depth minus the advanced stop distance t
  5. The advanced stop distance is automatically calculated by the control:
    • At a total hole depth up to 30 mm: t = 0.6 mm
    • At a total hole depth exceeding 30 mm: t = hole depth / 50
    • Maximum advanced stop distance: 7 mm
  6. The tool then advances with another infeed at the programmed feed rate F.
  7. The control repeats this procedure (steps 1 to 4) until the total hole depth is reached. The finishing allowance for floor is taken into account
  8. Finally, the tool retracts in the tool axis to the clearance height or to the position last programmed before the cycle. This behavior depends on the machine parameter posAfterContPocket (no. 201007).

Notes

  • This cycle can be executed only in the FUNCTION MODE MILL machining mode.
  • When calculating the infeed points, the control does not account for the delta value DR programmed in a TOOL CALL block.
  • In narrow areas, the control may not be able to carry out pilot drilling with a tool that is larger than the rough-out tool.
  • If Q13=0, the control uses the data of the tool that is currently in the spindle.

Note regarding machine parameters

  • Use the machine parameter posAfterContPocket (no. 201007) to define how to move the tool after machining. After the end of the cycle, do not position the tool in the plane incrementally, but rather to an absolute position if you have programmed ToolAxClearanceHeight.

Cycle parameters

Help graphic

Parameter

Q10 Plunging depth?

Tool infeed per cut (minus sign for negative machining direction). This value has an incremental effect.

Input: –99999.9999...+99999.9999

Q11 Feed rate for plunging?

Tool traversing speed in mm/min during plunging

Input: 0...99999.9999 or FAUTO, FU, FZ

Q13 or QS13 Rough-out tool number/name?

Number or name of the rough-out tool. You are able to transfer the tool directly from the tool table via the selection option in the action bar.

Input: 0...999999.9 or max. 255 characters

NC programs contained in this User's Manual are suggestions for solutions. The NC programs or individual NC blocks must be adapted before being used on a machine.

Change the following contents as needed:

  • Tools
  • Cutting parameters
  • Feed rates
  • Clearance height or safe position
  • Machine-specific positions (e.g., with M91)
  • Paths of program calls

Some NC programs depend on the machine kinematics. Adapt these NC programs to your machine kinematics before the first test run.

In addition, test the NC programs using the simulation before the actual program run.

 
Tip

With a program test you determine whether the NC program can be used with the available software options, the active machine kinematics and the current machine configuration.

Example

11 CYCL DEF 21 PILOT DRILLING ~

Q10=-5

;PLUNGING DEPTH ~

Q11=+150

;FEED RATE FOR PLNGNG ~

Q13=+0

;ROUGH-OUT TOOL