REGIMES OF MECHANICAL GRINDING
OF PYROCERAMIC COMPONENTS
IN THE SYSTEM MACHINE – WORKPIECE – TOOL – SCHEME
E. I. Suzdal’tsev,
A. S. Khamitsaev,
A. G. Épov,
and D. V. Kharitonov
Translated from Ogneupory i Tekhnicheskaya Keramika, No. 7, pp. 23 – 30, July, 2003.
Factors involved in the mechanical grinding of odd-profiled pyroceramic components and their effect on the
quality of product are discussed. Optimum conditions for tools, mechanical grinding regimes, schemes for
grinding inner and outer surfaces of conical components, and fine finish of the surface to a required level are
Notwithstanding a long history of over 50 years in the
design and development of engineering ceramics, technolo-
gists are still confronted with a range of problems concerned
with the final machining of structural components to the re-
quired size and shape [1 – 3]. At present, sufficient experi-
ence has been gained in the machining of large-size, odd-
shaped parts of quartz ceramics for radio engineering pur-
poses, in particular, the diamond grinding technique (pro-
gram or template-controlled) with a wall thickness tole-
rance of ± 0.1 mm and a surface roughness not exceeding
= 2.5 mm [4, 5].
Quite stringent requirements are placed on advanced
glass-ceramic components for use in radio engineering as
concerns the precision in size and shape (longitudinal, trans
verse, or cross-sectional), wall thickness, and surface finish.
It should be recalled that the optimum performance charac
teristics of radio materials vary with the operating wave
length and dielectric constant :
, n =1,2,3,...,
where d is the wall thickness of a component; l
free-space wavelength, e is the dielectric constant of the ma
terial, and q is the electromagnetic wave angle of incidence.
The higher the dielectric constant, the more stringent the
requirements placed on the wall thickness tolerance. By way
of example, for components of quartz ceramic with e =
3.0 – 3.5 the wall thickness tolerance is ± 0.1 mm, whereas
for components of polycrystalline glass ceramics Pyroceram
9606 or Pyroceram 9608 with e =6–8,thetolerance should
not exceed ± 0.02 mm .
These quite stringent requirements placed on the geomet-
ric tolerance of components made of polycrystalline glass ce-
ramic (henceforth for briefness pyroceramic) necessitate the
use of machining techniques. Furthermore, the use of ma-
chining becomes a necessity because of the significant
shrinkage of the heat-treated material (5.5 – 6.0%), which
may cause warping of the preforms [7 – 10]. The geometric
tolerance (in size, shape, and wall thickness) is typically con
trolled by at least three factors: machine used, component
machined, and machining tool.
With this in mind, our goal in this work was to consider
the effect of various machining conditions on the quality
characteristics of components produced from pyroceramic
EFFECTS DUE TO THE DIAMOND
As is known from theory , the grinding process is con
trolled by characteristics of the diamond instrument such as
diamond grade, grain fineness, diamond concentration, and
the type of lubricant used.
The effective wheel characteristics here are the cutting
force, tool wear, and roughness of the surface treated.
Pyroceramic specimens with dimensions of 70 ´ 70 ´
15 mm were used. Tests were carried out on a 3G71 sur
face-grinding machine under operating conditions: cutting
speed, 25 m/sec; depth of cut, 0.04 mm; cross-feed,
Refractories and Industrial Ceramics Vol. 45, No. 1, 2004
1083-4877/04/4501-0010 © 2004 Plenum Publishing Corporation
Tekhnologiya Research and Production Enterprise, Obninsk,
Kaluga Region, Russia.