Conventional Milling Versus Climb Milling
Climb Milling
Conventional Milling
Depending on the direction in which you move the workpiece against the end
mill you are either climb milling or conventional milling. As shown in the
illustration above, you are climb milling when the end mill turns as to climb the
slope made by cutting.
Climb milling has several advantages, and is often recommended for modern
milling machines. The flutes dig in to material with a climbing action, and the
workpiece and rotation of the cutter are going in the same direction. With this
forward stroke the tooth starts with a full chip and pushes the workpiece down
against the table or holding device. This requires less machine power, the
cutter does not dull as soon, and a better surface finish is produced.
However, climb milling requires a very rigid milling machine with virtually no
backlash. Because the workpiece and the milling cutter are moving in the same
direction, the milling cutter tends to pull the workpiece away from the driving
device if there is any backlash. This can overload the cutter and stall the
machine. Or it can simply leave a poor surface finish.
On light mills like the mini mill, use conventional milling for all but the lightest
cuts. Then, take your final cut of one or two thousandths of an inch using climb
milling for the best surface finish.
Plunge Milling
Plunge milling is the same action as drilling, but using a center cutting end mill
instead of a drill bit. This is how you start a slot that does not extend to the
edge of the workpiece.
Some end mills are center cutting. This means that one of the cutting edges on
the end of the end mill extends across the center of the end mill so that there
is a cutting edge for the full diameter of the end of the end mill.
Non–center cutting end mills have cutting edges on the end, but they do not
extend to the center. These end mills will cut on the end and can be used for
slotting and surfacing, but you cannot plunge a non–center cutting end mill
straight down into the workpiece.
24