HEIDENHAIN TNC 640 (34059x-04) Cycle programming - Manual (Page 139)

RECTANGULAR POCKET (Cycle 251, DIN/ISO: G251) 5.2
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TNC 640 | User's Manual Cycle Programming | 3/2014
139
5.2 RECTANGULAR POCKET (Cycle 251,
DIN/ISO: G251)
Cycle run
Use Cycle 251 RECTANGULAR POCKET to completely machine
rectangular pockets. Depending on the cycle parameters, the
following machining alternatives are available:
Complete machining: Roughing, floor finishing, side finishing
Only roughing
Only floor finishing and side finishing
Only floor finishing
Only side finishing
Roughing
1 The tool plunges the workpiece at the pocket center and
advances to the first plunging depth. Specify the plunging
strategy with parameter Q366.
2 The TNC roughs out the pocket from the inside out, taking the
overlap factor (parameter Q370) and the finishing allowance
(parameters Q368 and Q369) into account.
3 At the end of the roughing operation, the TNC moves the tool
tangentially away from the pocket wall, then moves by the set-
up clearance above the current plunging depth and returns from
there at rapid traverse to the pocket center.
4 This process is repeated until the programmed pocket depth is
reached.
Finishing
5 If finishing allowances are defined, the tool plunges the
workpiece at the pocket center and moves to the plunging
depth for finishing. The TNC first finishes the pocket walls, in
multiple infeeds if so specified. The pocket wall is approached
tangentially.
6 Then the TNC finishes the floor of the pocket from the inside
out. The pocket floor is approached tangentially.