A major change in the process
was a reduction in the speed of
both the buffs and the part spindle.
This was required to give the buff
enough time to access the opening and sufficiently buff the deep
recessed areas.
If either the buff speed or the
part spindle speed were too high,
an over-buff condition would form
on the high flats and corners,
while the lowest areas of the deep
recesses would not be finished.
Because this is a stamped stainless
steel part of a moderately thin
gauge, the corners are vulnerable
to buff cut-through.
So, the speed was reduced by as
much as 65 percent on the buffs
and by almost 80 percent on the
spindle, resulting in an SFPM of
less than 3,000—much lower than
the original targeted SFPM of 7,000
and the 9,000-10,000 that is chartrecommended.
Reduced cycle Time
Due to the shape and size of the
part, production requirements,
equipment type and availability,
and the targeted cost per piece, the
customer expected a cycle time of
between 45 and 60 sec. The final,
amended process produced a cycle
time of 50 sec. The cost per piece
was also right on the mark. Buffs
and compounds make up the greatest portion of that cost per piece,
and, by reducing the number of
buffs per head and adding spacing, setup costs were lower than
originally expected.
The increased buff diameter and
slow SFPM also resulted in reduced
wear on the buffs and increased
buff life. In addition, compound
usage was reduced as it was only
needed for cut and not for cooling
as it is with the high-SFPM process.
This project resulted in the
company receiving a contract for
this part of $2-3 million annually
and additional RFQs from existing
customers on similar parts.
The lessons learned can be summarized as: look to new products,
try new ideas and don't be afraid to
stray from the "rules of finishing"
to meet your requirements. The
unconventional may actually be
just what your business needs. n
Bob Pinchot is the field applications
manager for Osborn. For more information, please visit Osborn.com or call
800-720-3358.
LearnMORE
Making the Grade with
Mechanical Media
To understand how media grades are important
to good mechanical finishes, visit pfonline.
com/articles/making-the-grade-withmechanical-media.
pfonline.com 31