Siemens sinumerik 840D sl Operating Manual page 210

Creating a ShopTurn program
7.8 Tool, offset value, feedrate and spindle speed (T, D, F, S, V)
Feedrate (F)
The feedrate F (also referred to as the machining feedrate) specifies the speed at which the
axes move when machining the workpiece. The machining feedrate is entered in mm/min,
mm/rev or in mm/tooth. The feedrate for milling cycles is automatically converted when
switching from mm/min to mm/rev and vice versa.
It is only possible to enter the feedrate in mm/tooth during milling; this ensures that each
cutting edge of the milling cutter is cutting under the best possible conditions. The feedrate
per tooth corresponds to the linear path traversed by the milling cutter when a tooth is
engaged.
For milling and turning cycles, the feedrate during roughing is relative to the milling or cutting
center point. This is also applies to finishing, with the exception of contours with inner
curves. In this case, the feedrate is relative to the contact point between the tool and the
workpiece.
The maximum feedrate is determined via machine data.
Spindle speed (S)
The spindle speed S specifies the number of spindle revolutions per minute (rpm) and is
programmed along with a tool. The speed specified relates to the main spindle (S1) or
counter-spindle (S3) when turning and axial drilling, and to the tool spindle (S2) when drilling
and milling.
The spindle starts immediately after the tool change. The spindle stops upon reset, program
end, or a tool change. The spindle's direction of rotation is specified in the tool list for each
tool.
As an alternative to the spindle speed, you can also program the cutting rate. During the
milling cycles, the spindle speed is automatically converter into the cutting rated and vice
versa.
Cutting rate (V)
The cutting rate V is a circumferential velocity (m/min) and is programmed together with a
tool, as an alternative to the spindle speed. The cutting rate is relative to the main spindle
(V1) or the counter-spindle (V3) for turning and axial drilling, and corresponds to the
circumferential velocity of the workpiece at the point that is currently being machined.
However, for drilling and milling, the cutting rate is relative to the tool spindle (V2) and
corresponds to the peripheral speed at which the cutting edge of the tool machines the
workpiece.
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Machine manufacturer
Please refer to the machine manufacturer's specifications.
Operating Manual, 07/2010, 6FC5398-8CP40-0BA0
Turning