MAKE THE WHEEL ACT SOFTER (INCREASE
THE GRAIN DEPTH OF CUT)
Increase the work speed.
Decrease the wheel speed.
Reduce the diameter of the wheel and increase
MAKE THE WHEEL ACT HARDER (DE-
CREASE THE GRAIN DEPTH OF CUT)
Figure 10-2.--Surface grinding a flat workpiece.
Decrease the work speed.
Increase the wheel speed.
Increase the diameter of the wheel and decrease
As with other machine tools, the selection of the
proper speed, feed, and depth of cut is an important
factor in grinding. Also, coolants may be necessary for
some operations. The definitions of the terms speed,
feed, and depth of cut, as applied to grinding, are
basically the same as those in other machining
WHEEL SPEED, unless otherwise defined, means
the surface speed of the grinding wheel in fpm.
TRAVERSE (longitudinal or cross) is the rate that the
Figure 10-3.--Surface grinding a cylindrical workpiece.
work is moved across the working face of the grinding
One method used to determine the proper wheel
pass across the work. We'll explain each of these in the
speed is to set the speed between the minimum and
maximum recommended by the manufacturer. Take a
trial cut. If the wheel acts too soft, increase the speed.
If it acts too hard, decrease the speed.
Grinding wheel speeds commonly used in precision
grinding vary from 5,500 to 9,500 fpm. You can change
TRAVERSE (WORK SPEED)
wheel speed by changing the spindle speed or by using
a larger or smaller wheel. To find the wheel speed in
During the surface grinding process, the work
fpm, multiply the spindle speed (rpm) by the wheel
moves in two directions. As a flat workpiece is being
circumference (inches) and divide the product by 12.
from left to right (longitudinal traverse). This
longitudinal speed is called work speed. The work also
moves gradually from front to rear (cross traverse), but
this movement occurs at the end of each stroke and does
not affect the work speed. We'll explain how to set cross
traverse later in this chapter.
The maximum speed listed on a grinding wheel is
You should grind a cylindrical workpiece in a
not necessarily the speed at which it will cut best. The
manner similar to the finishing process used on a lathe
manufacturer decides the maximum speed based on the
strength of the wheel. That speed provides a margin of
the grinding wheel (lateral traverse), the work moves
safety and the wheel usually will cut better at a lower
from left to right (cross traverse).