How to ensure collision-free table rotations in RTCP
Mastercam programmers have various options (clearance, retract, feed plane) for defining approach and exit moves, however all these options can only generate motions along the tool axis.
On a machine with a C rotary table, 5-axes contouring operations such as the one illustrated below pose a significant problem when the machine is programmed in RTCP (Rotating Tool Centerpoint Programming). This type of programming (G43.4 or G43.5 on FANUC controls, TRAORI on Siemens 840D, etc.) uses a built-in linearization function which ensures that the tool tip always follows a straight line. As a result, all positioning moves between passes will result in collisions, as the machine will interpolate all 5 axes “through the part”.
The solution, when using an ICAM post-processor, consists in setting the post to automatically turn off RTCP at the end of each pass, rotate the C table to the start of the next cut, then turn on RTCP again.
Below is a macro example which captures the Mastercam-generated NCI record 1000 between passes and issues the commands that temporarily disable RTCP:
MODE/TLVEC,OFF $$ Turn off RTCP
CLAMP/OFF,CAXIS,TABLE,$NCM $$ Rotate the C table
MODE/TLVEC,ON $$ Turn on RTCP
Benefit to User
Prevent collisions when rotating the C table in RTCP mode.