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A. |
Yes
and No. It is true that almost all sand paper manufacturers
around the world (except most of those in the United
States) have adopted the Federation of European Producers
of Abrasives (FEPA) grading system, also known as
the "P" system. Most U.S. manufacturers have been
using a grading system established by the American
National Standards Institute (ANSI) for the Coated
Abrasives Manufacturers Institute (CAMI, or U.S. System)
which usually only refers to grades 12 to 600.
Under direct comparison, the systems are nearly identical
and interchangeable for 220 and below. For 240 and
above, the differences are greater as grit becomes
finer.
Remember, this is only a basic comparison of manufacturers'
methods of grading using particle size distribution
of mineral. Coarseness and scratch pattern must also
be determined by:
-
Type
and quality of grains
-
Shape
of grains
-
Method
of bonding
-
Hardness
of workpiece
In
addition, "P" grading is "purer" than the U.S. method,
containing fewer coarse and fewer fine particles resulting
in a more uniform system. Therefore, "P" graded paper
often has much finer scratch marks than the chart indicates.
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