Siemens SINUMERIK 808D User Manual page 223

Se quence of motions when finishing:
Finishing is performed in the order from the edge until the finishing allowance on the base is reached, and then the base is
finished. If one of the finishing allowances is equal to zero, this part of the finishing process is skipped.
● Finishing on the edge
While finishing on the edge, the tool traverses around the pocket contour only once.
For finishing on the edge, the path includes one quadrant reaching the corner radius. The radius of this path is normally 2
mm or, if "less space" is provided, equals to the difference between the corner radius and the mill radius.
If the final machining allowance on the edge is larger than 2 mm, the approach radius is increased accordingly.
The depth infeed is performed with G0 in the open towards the pocket center, and the starting point of the approach path
is also reached with G0.
● Finishing on the base
During finishing on the base, the machine performs G0 towards the pocket center until reaching a distance equal to
pocket depth + finishing allowance + safety clearance. From this point onwards, the tool is always fed in ve rtically at the
depth (since a tool with a front cutting edge is used for base finishing).
The base surface of the pocket is machined once.
In sertion strategies
● Inserting vertically to the pocket center means that the current infeed depth calculated internally in the cycle (≤ maximum
infeed depth programmed under _MID) is executed in a block containing G0 or G1.
● Insertion at a helical path means that the cutter center point traverses along the helical path determined by the radius
_RAD1 and the depth per revolution _DP1. The feedrate is also programmed under _FFD. The direction of rotation of this
helical path corresponds to the direction of rotation with which the pocket will be machined.
The insertion depth programmed under _DP1 is taken into account as the maximum depth and is always calculated as
an integer number of revolutions of the helical path.
If the current depth required for an infeed (this can be several revolutions on the helical path) is reached, a full circle is
still executed to eliminate the inclined path of insertion.
Pocket solid machining then starts in this plane and continues until it reaches the final machining allowance.
The starting point of the described helical path is at the longitudinal axis of the pocket in "plus direction" and is
approached with G1.
● Insertion with oscillation to the central axis of the pocket means that the cutter center point is inserted oscillating on a
straight line until it reaches the next current depth. The maximum immersion angle is programmed under _RAD1, and the
length of the oscillation travel is calculated in the cycle. If the current depth is reached, the travel is executed once more
without depth infeed in order to eliminate the inclined insertion path. The feedrate is programmed under _FFD.
Ta king into account the blank dimensions
During solid machining of the pockets, it is possible to take into account blank dimensions (e.g. when machining precast
parts).
Programming and Operating Manual (Milling)
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