1. Materials of Bearings
The materials of the race and ball of bearing require enough hardness that meet the following qualities:
(1). Large fatigue strength against repeated stress due to fatigue fracture of the race surface which governs the life of the bearings.
(2). High limit of elasticity and high yield strength to prevent deformation when a large load is applied per unit area.
(3). Large abrasion resistance against sliding friction between the retainer and the ball.
(4). High strength against crack due to impact load and failure caused by improper fitting etc.
(5).Small secular change in dimension and shape due to change of structure or internal stress.
GCr15 Steel <JIS G4805>(High carbon chromium bearing steel) satisfies the above comparatively well, and its chemical composition is shown in the following table.
Chemical composition of high carbon chromium bearing steel
Class | Standard | Symbol | Chemical Composition (%) | |||||
C | Si | Mn | P | S | Cr | |||
1 | GB | GCr15 | 0.98-1.10 | 0.15-0.35 | <0.50 | <0.025 | <0.025 | 1.30-1.60 |
DIN | 100Cr6 | |||||||
ASTM | E5200 | |||||||
JIS | SUJ2 | |||||||
2 | GB | 9Cr18 | 0.98-1.10 | <1.00 | <1.00 | <0.025 | <0.025 | 16.00-18.00 |
DIN | X105CrMO17 | |||||||
ASTM | 440C | |||||||
JIS | SUC440C |
In order to maitain uniform qualit of materials, FK keeps fully equipped installations and performs strict acceotance tests and inspections based on the strict acceptance standards in addition to JIS-standards.
Kinds of test done at the FK are mainly chemical analysis, magnetic exploration, ultrasonic exploration, corrosion by strong acid, inspection of structure by naked eyes, inspection of structure by microscope, crusher test and hardness etc.
2. Material of the Cage and the Rivet
The material of cage is JIS G3141(Cold rolled carbon steel sheet and strip)SPCC, and it is formed by the press. The material of the rivet is JIS G3507 (Low carbon steel wire rods)SWRCH 12A.
3. Materials of Housings
The material of the housings is FC200 JIS G5501 (Gray iron casting) and the mechanical properties are shown in the following table.
Mechanical properties of Gray cast iron HT200
symbol | Thickness | Dia. Of | Tension test | Traverse braking | Pressure | Hardness | |
Tensile | Bender | Deflection | Hardness | ||||
(kgf/mm2) | (kgf/mm) | (mm) | kgf/mm2 | (HB) | |||
HT200 | Over 6-8 | 13 | Over 23 | 53 | 1.8 | 75 | 187-255 |
Over 8-15 | 20 | Over 22 | 45 | 2.5 | 75 | 170-241 | |
Over 15-30 | 30 | Over 20 | 40 | 2.5 | 75 | 170-241 | |
Over 30-50 | 45 | Over 17 | 34 | 3.0 | 75 | 170-241 | |
Over 50 | 60 | Over 16 | 31 | 4.5 | 75 | 163-229 |
Other Materials of Housings
Symbol | JIS number |
FCD40(QT400) | JIS G5502 |
SPCC(08) | JIS G3141 |
SUS304 | JIS G4304 |
4.Materials of Other Components
Components | Materials used | JIS symbols | JIS number |
Sleeve for adapter | Carbon steel for machine structural use | S25C | JIS G4051 |
Nut for adapter | Carbon steel for machine structural use | S25C | JIS G4051 |
Washer for adapter | Cold rolled carbon steel sheet and strip | SPCC | JIS G3141 |
Oil seal | Synthetic nitrile rubber | - | - |
Slinger | Cold rolled carbon steel sheet and strip | SPCC | JIS G3141 |
Hexagon set screw | Nickel chromium molybdenum steel | SCM 435 | JIS G4105 |
Hexagon wrench key | Nickel chromium molybdenum steel | SNCM630 | JIS G4103 |
Grease nipple | Free cutting brass bar | C3604 | JIS H3250 |