Tc 9-524 fundamentals of machine tools

Grinding End Milling Cutters
The peripheral teeth of end milling cutters are ground in the
same manner as the teeth of a plain milling cutter. When
grinding the end teeth of coarse-tooth end milling cutters, the
cutter is supported vertically in a taper sleeve of the end mill
fixture and then tilted to obtain the required clearance angle.
The end mill fixture is offset slightly to grind the teeth 0.001
to 0.002 inch lower in the center to prevent dragging. A dish-
shaped grinding wheel revolving about a vertical spindle is
used to grind end milling cutters.
Removing the Burrs
After the milling cutter is ground, the cutting edges should
be honed with a fine oilstone to remove any burrs caused by
grinding. This practice will add to the keenness of the cutting
edges and keep the cutting edges sharper for a longer period
of time.
CYLINDRICAL GRINDING
Cylindrical grinding is the practice of grinding cylindrical or
conical workplaces by revolving the workpiece in contact with
the grinding wheel. Cylindrical grinding is divided into three
general operations: plain cylindrical, conical grinding (taper
grinding), and internal grinding. The workpiece and wheel are
set to rotate in opposite directions at the point of contact
(Figure 5-21).
Plain Cylindrical Grinding
The step-by-step procedure for grinding a straight shaft is
given below. The shaft has been roughly turned prior to
grinding.
5-20

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TC 9-524
Check and grind headstock and tailstock centers if
necessary.
Check drilled centers of workpiece for accuracy.
Place a grinding wheel of the proper grain, grade,
structure, and bond on the wheel spindle.
Place wheel guards in position to cover the wheel
adequately.
Set the proper wheel speed on grinding machine (Table
5-2 in Appendix A).
Place the diamond dresser and holder on the machine
table and true and dress the grinding wheel.
Mount the headstock and footstock on the table.
Attach the proper size drive dog on the headstock end of
the workpiece.
Mount the workpiece between headstock and tailstock
centers. Use lubricant (oil and white lead mixture) on
tailstock center. Make sure centers fit drill center holes
correctly with no play.
Set the proper rotational work speed on the wheel head.
The general range of work speed for cylindrical grinding
is 60 to 100 SFPM. Heavy rough grinding is sometimes
performed at work speeds as low as 20 or 30 SFPM. Soft
metals such as aluminum are sometimes ground at speeds
up to 200 SFPM.
Position the table trip dogs to allow minimum table
traverse. The wheel should overlap each end of the
workpiece not more than one-half the wheel width to
assure a uniform straight cut over the length of the
workpiece.
Calculate the table traverse feed using this formula.