Special Working Condition Bearing Application and Protection Q&A

1. What key points should be noted in bearing selection and use under high-temperature working conditions (temperature ＞200℃)?
The core points are adapting to high-temperature performance and protection: in selection, prioritize heat-resistant material bearings (such as carburized heat-resistant steel, ceramic bearings) to avoid hardness reduction and accelerated wear of ordinary bearing steel at high temperatures; in lubrication, abandon conventional grease, select high-temperature synthetic lubricating oil (such as polyimide type) or solid lubricants (such as molybdenum disulfide coating) to prevent lubricant failure at high temperatures; in structure, choose open type or high-temperature resistant seals (such as metal labyrinth seals) to avoid high-temperature aging of rubber seals; in installation, reserve a larger thermal expansion clearance, use high-temperature resistant fasteners, and strengthen heat dissipation design to reduce the impact of the environment on bearing temperature.

2. Under humid and corrosive working conditions, what protective measures can be taken besides selecting stainless steel bearings?

Protective measures can be strengthened from three aspects: sealing, lubrication, and surface treatment: in sealing, adopt a double sealing structure (such as lip seal ring + labyrinth seal), and fill waterproof grease in the sealing cavity to block the intrusion of moisture and corrosive media; in lubrication, select grease with excellent rust and corrosion resistance (such as composite calcium-based, polyurea-based grease) to form a dense oil film to isolate corrosive media; in surface treatment, galvanize, chrome-plate, or blacken the bearing outer ring and bearing housing to improve surface corrosion resistance; in addition, regularly clean the bearing surface, replace deteriorated grease in a timely manner, and avoid the accumulation of corrosive media to accelerate damage.

3. Under high-speed rotation conditions (rotational speed ＞10,000 rpm), what problems are bearings prone to? How to avoid them?

Common problems include excessive high-temperature heating, excessive vibration and noise, accelerated wear of rolling elements, and cage damage. Avoidance measures: in selection, prioritize ball bearings (such as deep groove ball, angular contact ball bearings) or ceramic rolling element bearings, matched with high precision grades (P4 and above) and appropriate clearance; in lubrication, use lubricating oil (such as synthetic gear oil) and timely dissipate heat through a circulating lubrication system to prevent high-temperature carbonization of grease; in installation, ensure the coaxiality of the shaft and bearing housing, reduce eccentric vibration, and adopt a rigid, high-precision fit method; in structure, select lightweight, high-strength cages (such as copper alloy, phenolic resin cages) to reduce inertial force during high-speed rotation.

4. Under harsh working conditions with much dust and impurities (such as mining, construction machinery), how to protect and maintain bearings?

The core of protection is to block the intrusion of impurities, and the focus of maintenance is to clean and supplement lubrication in a timely manner: in protection, adopt a double sealing structure of labyrinth and contact type, add dust rings and dust baffles at the bearing end cover, and install protective covers outside the equipment if necessary to reduce dust entry; during installation, ensure the seals are installed in place to avoid dust leakage through gaps; in maintenance, shorten the lubrication cycle, regularly replace grease, and thoroughly clean residual impurities and old grease inside the bearing when replacing; regularly check the integrity of seals, replace damaged ones in a timely manner, and clean dust around the bearing to avoid impurity accumulation and infiltration.

5. What should be noted when selecting bearings for working conditions with large vibration and impact loads (such as crushers, vibrating screens)?

Selection should focus on impact resistance, vibration resistance, and structural stability: prioritize roller bearings (such as self-aligning roller bearings), which have strong line contact load-bearing capacity, can bear large impact loads, and their self-aligning performance can compensate for installation deviations and eccentricity caused by vibration; select high-strength cage materials (such as brass, alloy steel) to avoid cage deformation and fracture due to impact loads; choose C3 or C4 grade with larger clearance to buffer the impact of vibration on the bearing and reduce mutual extrusion of components; at the same time, adopt an interference fit with a slightly larger installation method to enhance the connection stability between the bearing and the shaft/bearing housing, avoiding loosening caused by vibration.

6. Under low-temperature working conditions (temperature ＜-20℃), what special requirements are there for bearing lubrication and installation?

Under low temperature, it is necessary to solve the problems of lubricant solidification and component shrinkage deformation: in lubrication, select grease with good low-temperature fluidity and low freezing point (such as synthetic lithium-based grease with freezing point ≤-40℃) to avoid jamming of bearings due to solidification of ordinary grease at low temperature; preheat the grease in advance before initial use to improve fluidity; in installation, low temperature will shrink the bearing and matching components, leading to loose interference fit, so it is necessary to appropriately increase the interference amount or adopt hot installation (heating temperature controlled at 60-80℃) to ensure tight fit after cooling; at the same time, select bearing materials with good low-temperature toughness to avoid component damage due to low-temperature embrittlement, and preheat at low speed in the initial operation stage, gradually increasing the rotation speed.