DEPENDENCE OF THE CUTTING AND POLISHING ABILITY
OF MAGNETIC-ABRASIVE POWDERS ON THE FORM
AND STRUCTURE OF THE PARTICLES
V. V. Nepomnyashchii,
T. V. Mosina,
S. M. Voloshchenko,
K. A. Gogaev,
and M. G. Askerov
Translated from Novye Ogneupory, No. 6, pp. 14 – 16, June, 2014.
Original article submitted July 9, 2013.
It is shown that fragmented particles are preferable to spherical particles for magnetic-abrasive finishing. The
cutting elements of such powders are microscopic projections that determine the roughness of the finished sur
faces. For a given volume of magnetic-abrasive powder, a decrease in the diameter of the particles increases
the number of cutting centers. To maximize metal removal over the duration of the polishing operation and
shorten the amount of time needed to reach the minimum value of Ra, it is necessary to use progressively finer
abrasive powders as Ra decreases during polishing.
Keywords: magnetic-abrasive granule, lines of force of a magnetic field, micro-geometry of particles, cutting
Composite magnetic-abrasive materials (MAMs) ensure
the maximum removal of material from the workpiece in
magnetic-abrasive finishing (MAF) conducted with particles
of different sizes. MAM performance depends on the condi-
tions which exist during MAF, the dimensions of the work
ing gaps, and the strength of the magnetic field. The shape of
the grains of magnetic-abrasive powders has a significant ef
fect on their cutting and polishing ability and a substantial ef
fect on their service conditions.
Inside the working gap of the MAF machine, Iron-based
magnetic-abrasive particles — which exhibit shape aniso
tropy — are oriented in such a way that their major axis is
parallel to the lines of force of the magnetic field and is per
pendicular to the surface of the workpiece. The surface is fin
ished by microscopic projections on the particles . In addi
tion to the magnetic forces, a magnetic-abrasive particle
pressed against the surface being finished is acted upon by a
frictional force that causes the motion of the particle to devi
ate in the direction of motion of that surface.
Here, the cutting angle becomes negative and increases
in absolute value, which adversely affects cutting conditions
. Studies of alsifer powders of spherical and fragmented
form have shown (Table 1) that a fragmented shape offers
more advantages than a sphere .
Powders obtained by the same method were used for our
investigation. Having a material of the same initial composi
tion and performing simultaneous nitriding made it possible
to obtain composite powders with granules having different
geometries on the macroscopic scale but similar parameters
(hardness, dispersity, dimensions) for the particles of the
abrasive component — nitrides of silicon and aluminum, sili
con carbide (green). The structural parameters of the gran
ules were also similar, particularly the density of the distribu
tion of the abrasive particles over the surface of the granules.
Tests were performed on powders with a granularity of
200/160. The spherical and fragmented powders therefore
Refractories and Industrial Ceramics Vol. 55, No. 3, September, 2014
1083-4877/14/05503-0188 © 2014 Springer Science+Business Media New York
Institute of Problems of Materials Science of the Ukrainian Acad
emy of Sciences, Kiev, Ukraine.
TABLE 1. Properties of Powders of the Alloy Alsifer 
Method of powder
of the granules
of the powder
Cutting ability, 10
before nitriding after nitriding
Melt atomization Spherical 1.24 2.98
rolling-mill rolls Fragmented 1.80 14.5