HEIDENHAIN SW 68894x-02 - Manual (Page 530)

530 Organization mode of operation
8.2
Pa
ra
met
ers
 BBG (drilling limitation elements): Contour elements intersected by
UBD1/UBD2
Centric predrilling – Oversizes
 UBD1/UBD2 have no effect when "Centric predrilling"
has been defined as main machining operation followed
by "Finish-drilling" as submachining operation in the
machining sequence (see smart.Turn and DIN
Programming User's Manual).
 Prerequisite: UBD1 > UBD2
 UBD2 must permit subsequent inside machining with
boring bars.
Oversizes
Point angle tolerance [SWT]
If the drilling limitation element is a diagonal element, TURN
PLUS prefers using a twist drill with suitable point angle. If no
suitable twist drill is available, an indexable-insert drill is
selected for the predrilling operation. SWT defines the
permissible point angle tolerance.
Drilling oversize – Diameter [BAX]
Machining oversize on drilling diameter (X direction – radius
value).
Drilling oversize – Depth [BAZ]
Machining oversize on drilling depth (Z direction – radius value).
BAZ is not considered if:
 A subsequent inside finishing operation is not possible
due to the small diameter.
 "dimin < 2* UBD2" in the finish-drilling step for blind
holes.