Owner's manual

Using Hemisphere Milling Cycles
Chapter 24
24-7
With a convex hemisphere, the plunge is actually a contour move to the
outward along the -X axis. This move cuts along the spherical contour,
axes X and Z, at the plunge feedrate specified by the E parameter. This
plunge simultaneously moves the X and Z axes by the D’and L’amounts.
After the plunge, the control moves the tool in a 360 degree circular path
around the plunge-position. After completing this circular path, the control
makes a rough cut, D parameter, outwards along the -X a xis. Another 360
degree circular path is cut that ends at the -X axis. This process is repeated
until the outer diameter of the pocket, plus the finish allowance H, is
reached. The tool is then raised by the clearance amount and m oved at
rapid feedrate back to the initial cut at the current level. This completes
machining of one L level.
Important: The outer diameter of the pocket is equal to the radius of the
hemisphere plus the tool diameter and the finish allowance.
If the programmed Z depth of the pocket has not been reached, another
plunge takes place simultaneously along the X and Z axes to the next L’
level. This level is then machined as described in the previous paragraphs.
This process is repeated until the programmed Z depth of the convex
hemisphere is reached, a t which time the tool is moved at rapid feedrate
along the Z axis back to the initial Z level. The tool is then moved at rapid
feedrate along the X and Y axes to its pre-cycle position.
Use the G88.6 hemisphere milling finishing cycle to remove the finish
allowance left on the sides of a concave or convex hemisphere. You can
use this cycle to finish a hemisphere formed by using a G88.5 roughing
cycle. Typically a tool change is made between the G88.5 and the G88.6
cycles.
Important: The active plane is selected using G17, G18, or G19. In this
chapter it is assumed that G17, the XY plane, is selected as the active
plane.
Important: Tool length and diameter offsets must be e ntered and active
prior t o the G88 block.
These features are prohibited during execution of pocket milling cycles:
MDI m ode
Tool offset changes through the offset softkey
24.2
Hemisphere Milling
Finishing Cycle (G88.6)