MILLING MACHINE OPERATIONS - OD1644
- LESSON 1/TASK 2
(8)
Hole Diameter. The hole diameter determines the size of arbor that
is necessary to mount the milling cutter.
(9)
Keyway.
A keyway is present
on
all
arbor-mounting
cutters
for
locking the cutter to the arbor.
(10)
Spiral or Helix Angle.
(a)
Plain milling cutters that are more than 3/4 inch in width are
usually made with spiral or helical teeth.
(b)
A plain spiral-tooth milling cutter produces a better and smoother
finish, and requires less power to operate.
(c)
A plain helix-tooth milling cutter is especially desirable where an
uneven surface or one with holes in it is to be milled.
(11)
Types of Teeth. The teeth of milling cutters are either right-hand
or left-hand, viewed from the back of the machine.
Right-hand milling
cutters cut when rotated clockwise; left-hand milling cutters cut when
rotated counterclockwise.
(a)
Saw Teeth.
Saw teeth similar to those shown in figure 23 on the
previous page are either straight or helical in the smaller sizes of plain
milling cutters, metal slitting saw milling cutters, and end milling
cutters.
The cutting edge is usually given about 5 primary clearance
angle.
Sometimes the teeth are provided with offset nicks which break up
the chips and make coarser feeds possible.
(b)
Formed Teeth. Formed teeth are usually specially made for machining
irregular surfaces or profiles.
The possible varieties of formed-tooth
milling cutters are almost unlimited. Convex, concave, and corner-rounding
milling cutters are of this type. Formed cutters are sharpened by grinding
the faces of the teeth radially. Repeated sharpenings are possible without
changing the contour of the cutting edge.
(c)
Inserted Teeth.
Inserted teeth are blades of high-speed steel
inserted and rigidly held in a blank of machine steel or cast iron.
Different manufacturers use different methods of holding the
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