Automatically lifting off upon an NC stop or a power failure with M148

Application

With M148 the control automatically retracts the tool from the workpiece in the following situations:

  • Manually triggered NC stop
  • NC stop triggered by the software, for example if an error has occurred in the drive system
  • Power interruption
 
Tip

Instead of M148, HEIDENHAIN recommends using the more powerful function FUNCTION LIFTOFF.

Requirement

  • LIFTOFF column in the tool management
  • You must define the value Y in the LIFTOFF column of the tool management.

  • Tool management

Description of function

Effect

M148 takes effect at the start of the block.

You can reset M148 with the following functions:

  • M149
  • FUNCTION LIFTOFF RESET

Application example

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.

11 M148

; Activate automatic retraction

This NC block activates M148. If an NC stop is triggered during machining, the tool is retracted by up to 2 mm in the positive direction in the tool axis. This avoids possible damage due to the tool or workpiece.

Without M148 the axes come to a stop upon an NC stop, meaning that the tool remains at the workpiece, which might result in surfaces blemishes on the workpiece.

Notes

  • When lifting the tool off with M148, the control will not necessarily lift it off in the tool axis direction.
  • The control uses the M149 function to deactivate the FUNCTION LIFTOFF function without resetting the liftoff direction. If you program M148, the control will automatically liftoff the tool in the direction defined by the FUNCTION LIFTOFF function.

  • Please note that for some tools, such as side milling cutters, automatic retraction does not make sense.
  • In machine parameter on (no. 201401), the machine manufacturer defines whether automatic liftoff is active.
  • In machine parameter distance (no. 201402), the machine manufacturer defines the maximum liftoff height.
  • In machine parameter feed (no. 201405), the machine manufacturer defines the speed of liftoff movement.