What Are Our Concerns About Bearings（8）

Q1:Why can’t bearings with bore 28 be found in the mechanical design manual?

A:Bearing with an inner diameter greater than 20mm is represented by multiplying the last two digits of the bearing model number by five, such as the last two digits of the bearing model number 205 multiplied by five inner diameter equals 25mm, and the last two digits of the bearing model number 206 multiplied by five inner diameter equals 30mm, so there is no bearing with an inner diameter of 28mm in the mechanical design manual. The bearing with an inner diameter of 28mm you checked is not in gb si.

Q2:What is the type of self-aligning bearing with outer diameter 270 and inner diameter 150 and thickness 73?

A:Self-aligning roller bearing, inner diameter 150mm, outer diameter 270mm, thickness 73mm.

In addition, 153530, tapered hole self-aligning roller bearing is the same size.

Q3:Bearing inner diameter 140mm outer diameter 210mm thickness 29mm what is the model?

A：Theoretically, it is the model of 6028, because the bearing has a model rule, which can be roughly found out.

The basic code of bearings has three contents, type code, size series code, inner diameter code.

— Type code. Different types of bearings are denoted by numbers or letters.

— Size series code. It consists of two digits, the first digit representing the width series (centripetal bearing) or height series (thrust bearing), and the last digit representing the diameter series. The dimension series means that bearings with the same inner diameter can have different outerdiameters, and the same outer diameter has different widths (or heights), so as to meet the bearing capacity of different requirements.

— Inner diameter code. Represents the size of the nominalinner diameter of the bearing, and is represented by numbers.

For example: 1.N2208

N: cylindrical roller bearing

22: Size series code (0) 2

08: Inner diameter d=8*5=40mm

Example: 2 Single row angular contact bearing: 7208AC, original bearing code: 46208

Inner diameter d=8*5=40mm

outer diameter  = 80mm

Width = 18mm

Q4:Given the required inner and outer diameters of bearings, how to calculate the type of bearings?

A:Bearing sizes are separated. According to the width of inner and outer diameters, check “General Scheme of Outline Dimensions of Rolling Bearing Centripetal Bearing” GB/T273.3.

Determine the size series,The bearing code can be determined according to the bearing type code.As shown in the GB/T272.

Q5:How to calculate the height size of the outer neck and inner neck of the bearing by bearing model?

A:Bearing models are divided into pre-code, basic code and post-code.

For example: 6206

6 is the code name of deep groove ball bearing.

20 is the centripetal deep groove ball bearing with a width of 2 and diameter of 0.

0 is a code name

6 represents clearance.

Q6:Where can I find the size parameters of 6205 series bearings: such as ball diameter, number and so on?

A:When selecting rolling bearings according to the requirements of mechanical work, it is mainly to determine the bearing type and external size.

Deep groove ball bearing Each ring has a continuous groove raceway centripetal ball bearing with a cross section of about one-third of the circumference of the ball. This kind of ball bearing, because the raceway is deeper, can withstand greater axial thrust. After selecting the 6205 type, you can use the table to check the diameter of the rotating shaft and bearing matching part of the bearing is 25 mm, and the thickness and outer ring size of the bearing are known, so you can design the bearing seat and other related sizes.

In the use of all kinds of bearings, the main concern isto pay attention to the requirements of bearing force, bearing and design related data manuals are available, the main dimensions such as inner diameter, outer diameter, thickness can be found. 

Q7:Bearing model inquiry imported bearing domestic bearing NTN material should have the performance?

A:1. Friction compatibility 2. Clamp insertion 3. Running-in 4. Fatigue resistance 7 corrosion resistance 8 cavitation resistance 9 compressive strength

Q8:What does 113640 bearing model mean?

A:113640 is an old name made in China

The new model is called :22340K self-aligning roller bearing with taper. 

Size: 200*420*138mm

Q9:What bearing is RA102RRB+COL?

A:Wide inner ring ball bearing

“RA” : a convex inner ring (wide inner ring);

“102” : Inner diameter size: 28.575mm

“RR” : double-sided sealing ring;

“B” : The outer ring is spherical

“COL” : outer garment

Q10:How to select tolerances for holes and shafts matched with bearings?

A:The dimensional accuracy of bearings is constant, and the tolerance range has been worked out at the factory.

Take ordinary grade (P0) 6308 bearing as an example: it can be found in the bearing tolerance table, bearing outer

ring tolerance is: upper difference: 0 lower difference: -0.011

According to the rotating mode and bearing mode of the bearing, the outer ring is generally fixed relative to the inner ring, and the bearing is fixed bearing, not the main bearing. According to these contents, it can be found in the recommended fit table of the housing hole: for bearings using the bearing seat, the recommended tolerance zone of the housing hole is H8.

H8 tolerance zone: upper tolerance +0.054, lower difference 0. It indicates clearance fit, large clearance: 0.065, small clearance 0.

Matching of bearing inner ring and shaft:

The tolerance of 6308 bearing inner ring is: upper difference 0, lower difference -0.012. According to: rotating load of inner ring and ordinary load, the recommended shaft fitting tolerance zone is: M5, upper difference: +0.020, lower difference: 0.009. Note: Large gap is 0.020, large interference 0.003.

To sum up: to determine the bearing and shaft, with the shell hole, according to the bearing rotation situation, load size, precision grade, query a series of tables, you can get the size.