Tc 9-524 fundamentals of machine tools

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TC 9-524
GANG MILLING
Gang milling differs from straddle milling in that two or
more cutters of different diameters or shapes are mounted on
the same arbor to mill horizontal surfaces. Cutter
combinations in gang milling are virtually unlimited and are
determined by the desired shape of the finished product.
SPLINE MILLING (EXTERNAL)
Splines are often used instead of keys and keyways to
transmit power from the shaft to a hub or gear. Splines are a
series of parallel keys and keyways evenly spaced around a
shaft or interior of a hub. Splines allow the hub to slide on the
shaft either under load or freely. This feature is found in
transmissions, automotive mechanisms, and machine tool
drives. Manufactured splines are generally cut by bobbing and
broaching; however, this discussion will be limited to field
expedient methods. Standard splines on shafts and spline
fittings are cut with 4, 6, 10, or 16 splines.
The dimensions depend upon the class of fit and the shaft
diameter. The class of fit may be permanent, sliding fit not
under load, and sliding fit under load. Table 8-8 in Appendix
A lists the standard dimensions for the different classes of fits.
Shafts may be milled several different ways.
The most common way is to use two side milling cutters
separated by spacers, with the width of the spacers equal to
the width of the spline. The splines are cut by straddle milling
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each spline to the proper depth and indexing around the shaft
for each spline. A narrow plain milling cutter is used to mill
the spaces between the splines to the proper depth. It may be
necessary to make several passes to mill the groove uniformly
around the shaft. A formed cutting tool or cutter may also be
used for this operation.