PLASTIC MECHANICAL ACTION PARTS
by Kawai America

Nearly three decades ago, Kawai engineers took a cue from airplane designers who were
starting to use alternative materials for the fabrication of parts subjected to harsh stress and
fatigue.  Kawai reasoned that a composite called ABS Styran (officially Acrylonitrile
Butadiene Sytrene) would be ideal for high-stress piano action parts like the hammer flange
and wippen assembly.  In the early seventies, Kawai offered its first ABS action parts.  Not
long after, carbon composites appeared in such products like tennis racquets and golf clubs.

"Tennis racquets provide the best example of the problems associated with wood for
high-stress applications," explains Brian Chung, Kawai America vice-president.  "Wooden
tennis racquets used to break fairly easily and always required a racquet press to counteract
the swelling, shrinking and eventual warping caused by changes in humidity.  By the early
1980's, every tennis racquet manufacturer in the world had abandoned wood in favor of
composite materials.   Kawai's decision to use ABS for certain high-stress action parts was
based on that same reasoning.  Simply put, if the application requires superior strength,
dimensional stability and long-term durability under stress, ABS is the an ideal material for
the task."

Despite the proven benefits, ABS pianos action parts have, over the years, been denounced
by some in the industry.  "It has been a source of controversy on the selling floor.  People
selling against Kawai have peppered sales presentations with anecdotal and unproven
remarks about the reliability and longevity of ABS action parts, " Chung added.  Now,
discussions about the merits of wooden actions parts versus ABS parts can be tempered
with scientific research, thanks to a recent study released by Abul B. Sadat, Ph.D, Professor
and Chair of the Industrial and Manufacturing Engineering Department at California State
Polytechnic University in Pomona, California.

It may be difficult for the average customer to negotiate some of Dr. Sadat's numerous
charts.  His conclusions, however, can be understood by all.  He writes, "ABS plastic exhibits
superior properties as compared with their wood counterpart.  One of the important findings
of this study may be attributed to the dimensional tolerances at manufacture and the
dimensional changes in environment as the wood parts proved to be inferior to ABS plastic.
The dimensional tolerances of the flange have a direct effect on the vertical alignment of the
hammer when used as piano parts.  The results of this experiment show that ABS plastic
flanges are manufactured at closer tolerances than the wood flanges and no significant
changes in dimensions were observed for the ABS flanges with changes in environment."

"It is time for other manufacturers to end the debate and begin to rely upon the scientific
facts," stated Jun Ando, executive vice-president, Kawai America.  "From this point on, the
intelligent consumer will know that ABS action parts are superior to wooden parts and that a
Kawai action is, without a doubt, the most stable action in the world.

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