Siemens SINUMERIK 840D sl Turning Operating Manual page 365

Pilot hole
The cycle optionally takes into account the depth of a pilot hole. This can be programmed with
abs/inc – or a multiple of the hole diameter (1.5 to 5*D is typical, for example) – and is assumed
that it is available.
If a pilot hole exists, the 1st drilling depth must be between the pilot hole and the final drilling
depth. The tool enters the pilot hole with reduced feedrate and reduced speed; these values
can be programmed.
Direction of spindle rotation
The direction of spindle rotation with which the tool enters and withdraws from the pilot hole can
be programmed as follows:
● with stationary spindle
● with clockwise rotating spindle
● with counterclockwise rotating spindle
This avoids long or thin drills from being broken.
Horizontal drilling
For horizontal drilling using spiral drills, entering the pilot hole is improved if the cutting edges
of the drill are also in the horizontal position. To support this, the alignment of the drill in the
spindle can be programmed for a specific position (SPOS).
The feedrate is stopped before reaching the pilot hole depth, the speed increased to the drilling
speed and the coolant switched in.
Soft first cut into the material
The entry into the material can be influenced, depending on the tool and the material.
The soft first cut comprises two partial distances:
● The first cut feedrate is maintained to a programmable first feed distance ZS1.
● An additional programmable feed distance ZS2 immediately following ZS1 is used to
continuously increase the first cut feedrate (with FLIN) to the drilling feedrate.
With chip breaking / swarf removal, this mechanism takes effect at each infeed.
The input parameters ZS1 and ZS2 are maximum values that are limited by the cycle to the
infeed depth to be executed.
Deep-hole drilling at the exit from the hole
It makes sense to reduce the feedrate when for through drilling the exit is inclined with respect
to the tool axis.
● Through drilling "no"
The machining feedrate is used when drilling to the final drilling depth. You then have the
option of programming a dwell time at the drilling depth.
● Through drilling "yes"
Up to the remaining drilling depth, you program drilling with the drilling feedrate and, from
that point onward, you program drilling with a special feedrate FD.
Turning
Operating Manual, 06/2019, A5E44903486B AB
Programming technology functions (cycles)
10.1 Drilling
365