Q: What is the difference between pseudo-Burlman indentations on the raceway of a rolling bearing and scratches caused by improper installation?
A: Pseudo-Burlman indentations are also called false Brinell indentations or pseudo-Burlman marks. A pseudo-Burlman indentation is defined as the appearance of false indentations in the contact area between the rolling elements and the raceway during periodic vibration due to the minute movement or rebound of the elastic contact surface. Depending on the vibration intensity, lubrication conditions, or load, corrosion and wear may occur simultaneously, forming shallow depressions on the raceway. For stationary bearings, the depressions appear at the rolling element pitch and often turn pale red or shiny.
Indentations distributed along the rolling element spacing on the raceway surface are not caused by improper installation. The indented surface is often brown (corrosion) and is particularly rough for ball bearings (damaged machined surfaces). Scratches in the axial direction of the ball bearing can be found. When the bearing rotates occasionally, several pseudo-Burlman marks will appear. Typical pseudo-Burlman indentations are shown in Figures 1 and 2.
Figure 1： shows pseudo-indentations on the inner ring of a cylindrical roller bearing, distributed according to the rolling element spacing.
Figure 2：Specimen from the thrust ball bearing dummy indentation (fretting wear) tester.
The cause of pseudo-Burlman indentations is the vibration energy of stationary machinery causing minute movements of components in the rolling contact area.
Remedies for pseudo-indentations include: eliminating or absorbing vibration; avoiding prolonged stationary operation of sensitive machinery; using safe equipment to unload or preload bearings during transport; using suitable lubricants (additives); and selecting a larger radial clearance for rotating loads.
For separable cylindrical roller or tapered roller bearings, there are material defects on the rolling elements and raceways that are parallel to the axis and equidistant from the rolling elements. Sometimes several sets of marks are present in the circumferential direction. These marks are usually only present in about 1/3 of the circumference, not the entire circumference, as shown in Figure 3. This scratch is caused by misalignment and rubbing between the individual raceway and the raceway with rolling elements during installation. This is especially dangerous when moving heavy components (such as when a heavy shaft containing the inner ring and rolling element assembly is pushed into the outer ring already installed in the bearing housing).
Remedies for this type of damage include: using suitable installation tools; avoiding misalignment; and, if possible, rotating the component slowly during installation.
Figure 3：Scratches on the inner ring of a cylindrical roller bearing are caused by tilting when the inner ring is installed into the rolling element assembly.
About LJHB:
LuoYang JinShuo Precision Bearing Co., Ltd. is mainly committed to the R&D and sales of high-precision bearings and other special products, and provides bearings and transmission parts with high performance for customers' equipment. With quick response, from pre-sales technical communication to on-time production delivery, as well as perfect after-sales service, we win the recognition and trust of customers.
Our main products include cylindrical roller bearings, tapered roller bearings, slew bearings, gear drives, spindle bearings, crossed roller bearings, turret bearings, thin-wall bearings, tandem roller bearings, spherical roller bearings, etc. The bearing dimensions rang from 100mm to 6000mm, the accuracy reaches P5, P4 and P2 levels. The bearing are widely used in mining and metallurgy, industrial equipment, industrial gearboxes, petroleum equipment, cranes, medical equipment, robotic equipment, etc. Among them, cylindrical roller bearings with better performance and high-precision deep groove ball bearings have been explored for high-speed tubular strander rotating cable equipment, which have completely replaced imports, saving customers costs and time, and improving work efficiency. It has been recognized and widely praised by customers.
Contact LJHB:
Address: Yiyang Bearing Industry Zone, Luoyang City, China 47100
Tel/Wechat: +86-18037970383
Whatsapp: +86-18037970383
Fax: 0086-379-65199160
E-mail: lyjh@lyjhbearing.com
Website: www.chinajhbearing.com
