While surface foot per minute is a good starting point, it
shouldn't be thought of as the
end-all for your finishing processes.
Changing the ProCess
The combination of buff size
and rpm resulted in SFPM of about
7,000, which is about 2,000 below
the charted recommendation
for stainless steel of 9,000-10,000
SFPM. However, this was the maximum SFPM that could be achieved
due to the limitations of buff size
to accommodate the size of part
and the limited ability to change
equipment speed.
While this process produced
acceptable results on all of the
standard 2D parts, it was never
successful in finishing the 3D
parts. To solve this problem, the
30
JUNE 2013
company changed every facet of
its existing process.
It first increased the buff diameter by 22 percent while keeping the
inside diameter the same, resulting
in an increased amount of usable
material that could reach deep into
the part. The buff constructions
and material types remained the
same or similar, but the dip treatments were changed to increase the
flexibility and the cut rate.
Next, the company had to identify which heads would buff which
areas of the recessed openings.
The buff heads then were built
with spacing to open up the head
and create flexibility to maneuver
around the recessed areas. The
number of buffs per head was
also reduced to narrow the head
enough to enable the buffs to fit
into the openings.
In addition, the heads were
realigned so that the buffs had optimum access within the opening.
One constant was the compound
selection. Because the metal was
very good quality, it was determined that the existing compound
selections would be adequate. If
the metal was stretched or pitted, a
more aggressive cut and color compound would have been selected.