MILLING MACHINE OPERATIONS - OD1644 - LESSON 1/TASK 1
(i)
When setting the depth of the cut, the workpiece should be brought
up to just touch the revolving cutter. After a cut has been made from this
setting, a measurement of the workpiece is taken. The graduated dial on the
traverse feed is then locked and used as a guide in determining the depth of
the cut.
1
When starting the cut, the workpiece should be moved so that the
cutter is nearly in contact with its edge, after which the automatic feed
may be engaged.
2
When a cut is started by hand, care must be taken to avoid pushing
the corner of the workpiece between the teeth of the cutter too quickly, as
this may result in cutter tooth breakage.
3
In order to prevent time wasting during the operation, the feed
trips should be adjusted to stop table travel just as the cutter clears the
workpiece.
i.
Straddle Milling.
(1)
General. When two or more parallel vertical surfaces are machined at
a single cut, the operation is called straddle milling. Straddle milling is
accomplished by mounting two side milling cutters on the same arbor, set
apart so that they straddle the workpiece.
(2)
Operation.
Figure 17 on the following page illustrates a typical
example of straddle milling. In this case a spline is being cut, but the
same operation may be applied when cutting squares or hexagons on the end of
a cylindrical workpiece. The workpiece is usually mounted between centers
in the indexing fixture, or mounted vertically in a swivel vise. The two
side milling cutters are separated by spacers, washers, and shims so that
the distance between the cutting teeth of the cutters is exactly equal to
the width of the workpiece area required.
When cutting a square by this
method, two opposite sides of the square are cut, then the spindle of the
indexing fixture or the swivel vise is rotated 90 and the other two sides
of the workpiece are straddle milled.
j.
Gang Milling.
Gang milling is the term applied to an operation in which two or more
milling cutters are used together
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