Owner's manual

Using Hemisphere Milling Cycles
Chapter 24
24-8
The following subsections cover using the G88.6 finishing cycle for
concave or convex hemispheres.
Use the G88.6 c oncave milling finishing cycle to finish a concave pocket
in a workpiece. This cycle is typically used to remove the finish allowance
that was l eft on the sides of the concave hemisphere during the G88.5
roughing cycle.
The G88.6 block used to finish a concave pocket has this format:
G88.6 X__Y__Z__R__Q0_P__H__L__E__F__;
Where : Is :
XY
The coordinates thatspecify the centeroftheconcavehemisphere inthe
selected plane.
Z
The coordinate (along the plungingaxis)thatspecifies the bottomofthe
hemisphericalpocket. In incremental mode this parameterspecifies the depth of
the pocketasmeasured fromthe startlevelto the pocketbottom. This
parametermustbe programmed.
R
Radiusofthe concavehemisphere.
Q0
Codespecifying aconcavehemisphere.
P
Directionoffinishingcut. This parameterdetermineswhether the finishing cuts
areperformed ina clockwiseor counter-clockwise motion. P0specifies
clockwise. P1 specifiescounter-clockwise.
Important: Ifcuttercompensation(G41/G42)was enabled priortothe
G88.6 block,it is disabled whenG88.6isenabled.
H
The finishallowancethatwill be lefton the sidesofthe concavehemisphere.
Thisis anoptional parameter thatisprovidedtoallowformultiple finishingcuts.
L
Finishingcuspheight. Thisvalue ofthisparameterisa measurementthat
correspondstotheheightofthe materialleftalong thesides of thehemisphere
aftereachX-Zroughingplunge.
E
Plungefeedrate. ThisparameterdeterminesthefeedrateofanyZ axismoves. If
notprogrammed the roughing feedrate (F)will beused.
F
Finishingfeedrate. If notprogrammedtheexisting (modal)feedrate will beused.
If Q0 is programmed, the control makes a finish pass around the sides of a
concave hemisphere. The control makes multiple circular finish cuts at
each level of the concave hemisphere. The depth of the pocket increases
and the diameter of each level decreases until the bottom center of the
concave hemisphere is reached.
Prior to each finish plunge, the control computes a delta finish cut
thickness, D’, and a delta plunge depth, L’. These computations are based
on the c usp height (L parameter) and the hemisphere radius (R parameter)
programmed in the G88.6 block, and the tool radius programmed prior to
the G88.6 block.
24.2.1
Concave Hemisphere
Finishing Using G88.6