Bearing Type |
Size(mm) |
Steel Balls Limit Speed(r/min) |
Ceramic Balls Limit Speed(r/min) |
Weight(kg)≈ |
|||||
d |
D |
B |
r(min) |
r1(min) |
Grease Lubrication |
Steel Balls |
Ceramic Balls |
||
H7006C-2RZ
|
30
|
55
|
13
|
1.0
|
0.30
|
23500
|
35000
|
0.110
|
0.094
|
H7007C-2RZ
|
35
|
62
|
14
|
1.0
|
0.30
|
20500
|
31000
|
0.145
|
0.134
|
H7008C-2RZ
|
40
|
68
|
15
|
1.0
|
0.30
|
18500
|
28000
|
0.175
|
0.161
|
H7009C-2RZ
|
45
|
75
|
16
|
1.0
|
0.30
|
16700
|
25000
|
0.245
|
0.230
|
H7010C-2RZ
|
50
|
80
|
16
|
1.0
|
0.30
|
15000
|
23000
|
0.260
|
0.240
|
H7011C-2RZ
|
55
|
90
|
18
|
1.0
|
0.30
|
13800
|
21000
|
0.380
|
0.350
|
H7012C-2RZ
|
60
|
95
|
18
|
1.1
|
0.60
|
13000
|
19000
|
0.410
|
0.376
|
The bearings matched ways as below :
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DBThe load lines in a pair of bearings by back to back assembly are enlarging from the bearing axis. It can bear axial load in two directions and relative larger moment because of larger angular rigidity.
|
DFThe load lines in a pair of bearings by face to face assembly are convergence toward the bearing axis. It can bear axial load in two directions and smaller moment because of smaller angular rigidity. |
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DTA pair of bearings by series a ssembly only bear axial load in one direction, but it is able to bear larger axial load related to DB and DF. |
TBTThe tri-bearing matching TBT or TFT isobtained by increasing the same type of the bearing based on DB or DF There are higher axial and radial rigidity for TBT and TFT, so larger load can be supported. |
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QBCThe four bearing matching QBC (or QFC) is obtained by matching double set of DB (or DF) bearings. QBT (or QFT) is formed when three bearings are installed in a same direction and another one back (or face) to them. |
PBCDivide the five bearings into two groups of three and two bearings respectively, in which the bearings are all installed in the same direction, PBC is formed when the groups match each other by back to back and PFC by face to face. If four bearings are installed in the same direction and another one back (or face) to them, then PBT (or PFT) is formed. |
REASONS | BENEFIT |
REDUCED RUN OUT (P4,P2) |
HIGH WORKPIECE ACCURACY |
HIGH SPEED |
SHORTER WORKING TIME BETTER SURFACE FINISHING |
LOW FRICTION |
LOW WORKING TEMPERATURE |
PRELOAD |
HIGH STIFFNESS |
How to choose the bearings series during the real application?
MACHINE | BEARING TYPE | BEARING SERIES |
TURNING | HIGH LOAD | 70/719/72 |
MILLING | HIGH LOAD | 70/719/72 |
MACHINING CENTER | HIGH SPEED | H70/H719 |
HIGH SPEED MILLING | HIGH SPEED +CERAMIC BALL | H70+CERAMIC BALL |
GRINDING | HIGH SPEED +CERAMIC BALL | H719+CERAMIC BALL |
H718+CERAMIC BALL | ||
BEARING TYPE | SPEED FACTOR | LUBRICATION | |
HIGH LOAD | <1.0 Mndm | Grease | |
>1.0 Mndm | Oil Bath or circulation | ||
HIGH SPEED | <1.5 Mndm | Grease | |
>1.5 Mndm | Oil injection or mist or air-oil | ||
HIGH SPEED+CERAMIC BALL | <1.8 Mndm | Grease | |
>1.8 Mndm | Air-oil or minimal oil lubrication |
How to calculate the speed factor
Speed factor ndm is calculated to compare working conditions of different bearings, regardless their dimensions.
D = outer diameter (mm)
d = bore diameter (mm)
n = shaft speed (rpm)
dm = pitch diameter (mm)
dm = 0.5x(D+d)
ndm = dm x n
How to calculate the grease qty?
Q0 = 33% free space
Q = Q0 x K [cm3]