Thin Section Deep Groove Ball Bearings & Miniature bearings Pushed Wheelchairs to Run Well

Not long ago, an original solution of thin section deep groove ball bearings & miniature bearings was born in Lily Bearing. The solution, which was used in a client’s electric wheelchairs, proved successful. The client is a large intelligent motor company. It produces a numerous of advanced electric wheelchairs which can change into a sofa seat, a recliner, a stair climber, a speed adjuster, a user stander, etc. Users can smoothly control the operation of wheelchairs, only using human organs such as hands, the head and even the respiratory system. With such powerful functions, it is obvious that the special wheelchairs need strong and slim bearings.

After a good knowledge of working conditions of the client, engineers of Lily Bearing recommended a combined solution. They said 6903-2RS, 6904-2RS series of thin section deep groove ball bearing s and 628-2RS series of miniature bearings would be proper for the client's electric wheelchairs. The engineers said, “... both thin wall deep groove ball bearings and small bearings take up less space and can also reduce friction... Meanwhile, these bearings can provide excellent operating accuracy without compromising the performance of the bearings.” They also gave a professional instruction of the two thin section deep groove ball bearings and 628-2RS miniature bearings according to their respective characteristics and their specific technical parameters, such as the bearing material, the design, the loads, the seal, the cage, ABEC grade, the radial clearance, the lubrication and other factors. The analysis of detailed technical parameters is as follows:

Materials

The ring material and the ball material of 6903-2RS, 6904-2RS thin section deep groove ball bearings and 628-2RS miniature bearings are 52100 Chrome Steel. In terms of physical properties, this material has high load capacities and low noise characteristics. In addition, the cage material of the above three types of bearings are made of 300 series stainless steel, which can withstand high loads and high rotational speeds and also has the function of rust prevention. Long-term practice has proved that the high strength-to-wear ratio of 52100 chrome steel and 300 series stainless steel, which is essential for the efficient operation and even longer life of 6903-2RS, 6904-2RS thin section deep groove ball bearings and 628-2RS miniature bearings.

6903-2RS Thin Section Deep Groove Ball Bearings

Sealing

As far as the sealing type is concerned, 6903-2RS & 6904-2RS thin section deep groove ball bearings and 628-2RS miniature bearings are sealed, which can ensure that both these thin wall bearings and miniature bearings are in a highly clean space. The clean space can provide a good foundation for smooth running of the thin section deep groove ball bearings and miniature bearings.

Inner and Outer Diameters

6903-2RS, 6904-2RS thin section deep groove ball bearings have an inner diameter of 17mm and 20mm respectively, and an outer diameter of 30mm and 37mm respectively. The 628-2RS miniature bearings belong to series of micro bearings. Its inner diameter is less than 10mm, specifically 8mm, and its outer diameter is 24mm. 

The inner and outer diameter tolerances of these three series of bearings are slightly different. 6903-2RS series of thin section deep groove ball bearings and 628-2RS series of miniature bearings keep the same bore dia tolerance, both in the range of -0.008mm to 0, while 6904-2RS series of thin section deep groove ball bearings have a slightly larger bore dia tolerance in the range of -0.01mm to 0.

6904-2RS series of thin section deep groove ball bearings have the largest outer diameter tolerance range of [-0.011mm, 0]. 6903-2RS series of thin section deep groove ball bearings have the second largest outer dia tolerance range of [-0.009mm, 0]. It is worth mentioning that 628-2RS series of miniature bearings have the same outer diameter tolerance range as the inner diameter tolerance range, both in the range of [-0.008mm, 0].

6904-2RS Thin Section Deep Groove Ball Bearings

Width

The width of the 628-2RS series miniature bearings is equal to the inner diameter, which is 8mm. The width of both of the thin section deep groove ball bearings is smaller than the the inner diameter, and the inner diameter is about twice the width. Although there are some differences in the widths of the two thin section deep groove ball bearings and 628-2RS series of miniature bearings, the range of their width tolerances remains the same, all within the range of [-0.120mm, 0].

Loads

Before analyzing the loads, let's start with the structure and load direction of the above thin section deep groove ball bearings and miniature bearings. All these bearings are single row bearings and the load direction is radial. The main differences lie in the static radial load and the dynamic radial load.

The static load is a kind of capacity a bear can withstand at rest or in a low speed. The static loads of 6903-2RS, 6904-2RS thin section deep groove ball bearings are 575lbs and 827lbs respectively. In this case, the bearings are not affected by the acceleration factors due to the offset of balancing effect of the acting and reaction forces.

The dynamic load is related to the force on the bearings and the state of motion such as shock and vibration. 6903-2RS & 6904-2RS thin section deep groove ball bearings can withstand a dynamic radial load of 1032 lbs and 1434lbs respectively. In the case of dynamic loading, the bearing forces are unbalanced and the thin wall ball bearings are subject to acceleration factors.

Compared with 6903-2RS & 6904-2RS thin section deep groove ball bearings, the static and dynamic radial loads of 628-2RS series miniature bearings are both small, 1138N and 2833N respectively.

Through the load characteristics of the above thin section deep groove ball bearings and miniature bearings, it is easy to find that the ratio of the static radial load to the dynamic radial load is roughly 50%.

628-2RS Miniature Bearings

Extreme Speed

During the rotation of thin section deep groove ball bearings and miniature bearings, the heat is generated inside them due to friction, and this heat accelerates the internal temperature of the bearings. When bearings rotate above a certain speed limit, the bearings themselves may be at risk of burnout. The max speed varies from bearing to bearing. The limit speeds of 6903-2RS & 6904-2RS thin section deep groove ball bearings, are 22(X1000 rpm) and 19(X1000 rpm) respectively, both of which are lower than the max speed of miniature bearings. The max speed 628-2RS miniature bearings is 28(X1000 rpm).

Clearance

For thin section deep groove ball bearings and miniature bearings, the internal clearance plays a key role in the process of operation. It has a direct relationship with the bearing vibration, noise, friction, loads as well as other factors. If the clearance is too large, then the precision of thin section deep groove ball bearings and miniature bearings will be reduced and vibration and noise will be increased, which directly affects the service life of the bearings. The radial clearance level of 6903-2RS & 6904-2RS thin section deep groove ball bearings is C0. The radial clearance level of 628-2RS miniature bearings is generally MC3. MC1/2/4/5/6 can also be available. Lily’s engineers said that it was important to match the corresponding clearance grade according to the bearing type and working conditions.

The above Thin Section Deep Groove Ball Bearings and miniature bearings have low rotational torque and high rotational accuracy. They are designed for mainly radial loads. The following table shows the technical parameters of 6903-2RS, 6904-2RS series of thin section deep groove ball bearings and 628-2RS series of miniature bearings.

Technical Parameters of 6903-2RS, 6904-2RS & 628-2RS

To sum up, the combined solution of 6903-2RS & 6904-2RS thin section deep groove ball bearings and 628-2RS miniature bearings could ensure the efficient operation of the client's electric wheelchairs. Further, this solution can also ensure that the design size can be reduced without sacrificing the performance of thin section deep groove ball bearings and miniature bearings. The client fully affirmed this bearing solution. Actually, Lily Bearing always sticks to the concept of "Clients come first". While providing the client with high-quality thin section deep groove ball bearings and miniature bearings, more importantly, Lily Bearing also provided the client with specialized solutions suitable for their working conditions. This should thank to over 20 years’ experience of bearings.

• Previous: Four-row Tapered Roller Bearings Drove I-beam Rolling Mills to Run Smoothly
• Next: How to Optimize Your Bearing Lubrication