When the incorrect cutting tools are used, production can grind to a stop.
And, the decisions made about which tools
to use in any given operation—particularly
if that operation is tricky—are among the
most important and most debated in modern
shops. Dozens of manufacturers offer literally thousands of choices.
Canadian Metalworking asked Tom Hagan,
milling product manager for Iscar Tools,
and Dan Cormier, application specialist for
Dormer Pramet, to describe how the best
surface finish can be achieved using today’s
tooling. Here is what they had to say.
CM: WHAT ARE THE PRIMARY GOALS OF A
Hagan: There are two main goals of finishing: mate and cosmetic look. If the goal
is mate, a certain finish on parts must be
attained to get two or more parts to mate
A lot of times, however, the finish pass is
performed simply to produce an attractive,
CM : HOW CAN A MACHINIST BEST PREPARE FOR
THE FINISHING PASS?
Hagan: Tool choice, setup, and cutting data
all need to be selected correctly. Tool choice
and speeds and feed depend on the material
being machined for the most part, and setup,
while important in every machining operation, is even more important in finishing.
Any instability in the tool, shank, or adapters can create runout that will negatively
affect the surface finish.
It’s also important to leave enough material
behind after the roughing pass to do an adequate depth of cut during the finishing pass.
For example, if you leave less than 0.030 in.
of material behind, it can be difficult to get
the pass just right.
Skim passes can be hard to get right
because you want to be cutting and not rubbing the part.
FINISHING THE JOB
Avoid rubbing the part during the finishing pass by leaving enough
material during roughing
Cutting parameters for the finishing skim pass must
be set correctly to help ensure you are cutting and not
rubbing the part.
IMAGE COURTESY OF ISCAR TOOLS.