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Semimanufactured metal-graphite
having MGR symbol, is a hard or very hard material
with a low friction coefficient and low falling voltage in the contact brush-collector,
runing
with reduces losses. Electric brushes manufactured by these semimanufactured
runs and
supports very well in runing high densityes of current.
Metal-graphite semimanufactured are manufactured in twelve qualities
as follows:
MGR-10, MGR-12, MGR-14,
MGR-15, MGR-16, MGR-17, MGR-18, MGR-20, MGR0-23,
MGR-24, MGR-25, MGR-26.
Brushes made from metal-graphite
are recomandedfor to equip: D.C. motors with rings,
general usage motors, motors for siderurgical industry.
For automobile industry, are recomanded the following marks:
MGR-12, MGR-15, MGR-16,
MGR-17, MGR-23, MGR-26.
Table
with parameters of running recommanded for
metal-graphite materials in normal conditions of
running
|
Group
of semimanufactured
|
Mark
|
Density
of curent
|
Peripheral
speed max.
|
Pressure
on brush
|
|
|
A/cm²
|
m/s
|
kN/m²
|
|
0
|
1
|
2
|
3
|
4
|
|
METAL
GRAPHITE
|
MGR-10
|
15
|
35
|
15...25
|
|
MGR-12
|
20
|
30
|
20...35
|
|
MGR-14
|
20
|
30
|
20...30
|
|
MGR-15
|
20
|
20
|
18...20
|
|
MGR-16
|
20
|
20
|
22...60
|
|
MGR-17
|
15
|
25
|
18...22
|
|
MGR-18
|
20
|
40
|
20...30
|
|
MGR-20
|
20
|
20
|
18...20
|
|
MGR-23
|
12
|
40
|
20
|
|
MGR-24
|
20
|
20
|
20
|
|
MGR-25
|
20
|
20
|
20
|
|
MGR-26
|
20
|
30
|
20...35
|
Phisical characteristics
of the metal-graphite materials could be determined using a tubes
of sizes 4x8x32 mm or 10x10x64 mm according to STAS 10223/1-75.
Fuctional characteristics: falling voltage, friction coefficient and middle
wear speed values
are determinated in laboratory conditions on two pieces of testing brushes
on sizes
12,5x25x40 mm according to STAS 10223/3-84. For the folling voltages, friction
coefficient
and medium wear speed values (point 6,7 and 8) are necesary the following conventional
conditions of testing:
|
TESTING
CONDITIONS
|
VALUES
|
|
peripheral
speeds
|
15 or 25 m/s
|
|
density
of current
|
15,
16 or 20 A/cm²
|
|
pressure
on brush
|
22
kN/m²
|
|
current
|
continous
|
|
temperature
|
60°C
|
|
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