German STRACK bearings, STRACK models, STRACK prices

STRACK bearings are precision mechanical components that convert sliding friction between the rotating shaft and the bearing housing into rolling friction, thereby reducing frictional losses. Rolling bearings generally consist of four parts: inner ring, outer ring, rolling elements, and cage. The inner ring fits with the shaft and rotates with it; the outer ring fits with the bearing housing to provide support; the rolling elements are evenly distributed between the inner and outer rings by the cage, and their shape, size, and quantity directly affect the performance and service life of the rolling bearing; the cage ensures even distribution of the rolling elements, guides their rotation, and provides lubrication.

STRACK bearing classification

There are many types of plain bearings: 1) According to the direction of load they can withstand, they are divided into radial (centripetal) plain bearings and thrust (axial) plain bearings. 2) According to the type of lubricant, they are divided into oil-lubricated bearings, grease-lubricated bearings, water-lubricated bearings, gas bearings, solid-lubricated bearings, magnetic fluid bearings, and electromagnetic bearings, totaling 7 categories. 3) According to the thickness of the lubricating film, they are divided into thin-film lubricated bearings and thick-film lubricated bearings. 4) According to the bearing shell material, they include bronze bearings, cast iron bearings, plastic bearings, jewel bearings, powder metallurgy bearings, self-lubricating bearings, and oil-impregnated bearings. 5) According to the bearing shell structure, they include circular bearings, elliptical bearings, three-lobe bearings, step-face bearings, tilting-pad bearings, and foil bearings. Bearing shells are divided into split and integral structures. To improve the friction properties of the bearing shell surface, one or two layers of anti-friction material are often cast on the inner diameter surface, commonly known as bearing lining; thus, there are bimetallic and trimetallic bearing shells. The bearing shell or bearing lining is an important part of a plain bearing, and the materials for both are collectively referred to as bearing materials. Since the bearing shell or lining is in direct contact with the journal, and the journal is generally more wear-resistant, the main failure mode of the bearing shell is wear. Wear of the bearing shell is directly related to the journal material, the bearing shell material itself, the lubricant, and the lubrication state. These factors should be comprehensively considered when selecting bearing shell materials to improve the service life and performance of plain bearings.

STRACK bearing grease selection

1) When the bearing load is high and the speed is low, select grease with low penetration; conversely, select grease with high penetration. For high-speed bearings, select grease with lower penetration and good mechanical stability. Note that the viscosity of the base oil in the grease should be relatively low. 2) The dropping point of the selected grease should generally be 20-30℃ higher than the operating temperature. In cases of continuous high-temperature operation, ensure that the permissible temperature range of the grease is not exceeded. 3) When plain bearings operate in water-splashed or humid environments, select calcium-based, aluminum-based, or lithium-based greases with good water resistance. 4) Select grease with good adhesion. Selection of grease for plain bearings: Load<1MPa, journal circumferential speed below 1m/s, maximum operating temperature 75℃, select No. 3 calcium-based grease; load 1-6.5MPa, journal circumferential speed 0.5-5m/s, maximum operating temperature 55℃, select No. 2 calcium-based grease; load >6.5MPa, journal circumferential speed below 0.5m/s, maximum operating temperature 75℃, select No. 3 calcium-based grease; load<6.5MPa, journal circumferential speed 0.5-5m/s, maximum operating temperature 120℃, select No. 2 lithium-based grease; load >6.5MPa, journal circumferential speed below 0.5m/s, maximum operating temperature 110℃, select No. 2 calcium-sodium based grease; load 1-6.5MPa, journal circumferential speed below 1m/s, maximum operating temperature 50-100℃, select No. 2 lithium-based grease; load >5MPa, journal circumferential speed 0.5m/s, maximum operating temperature 60℃, select No. 2 rolling mill grease; in humid environments, at temperatures around 75-120℃, consider using calcium-sodium based grease. In humid environments, if the operating temperature is below 75℃ and No. 3 calcium-based grease is unavailable, aluminum-based grease can be used. At operating temperatures of 110-120℃, lithium-based or barium-based grease can be used. For centralized lubrication, use grease with lower consistency. Lubrication cycle for plain bearings: Occasional operation, non-critical parts: Shaft speed<200r/min, lubricate once every 5 days; shaft speed >200r/min, lubricate once every 3 days. Intermittent operation: Shaft speed<200r/min, lubricate once every 2 days; shaft speed >200r/min, lubricate once every 1 days. Continuous operation, operating temperature less than 40℃: Shaft speed<200r/min, lubricate once every 1 days; shaft speed >200r/min, lubricate once per shift. Continuous operation, operating temperature 40-100℃: Shaft speed<200r/min, lubricate once per shift; shaft speed >200r/min, lubricate twice per shift. Ensure uniform and close contact between the journal and the plain bearing, while maintaining a certain clearance. This refers to the central angle subtended by the contact surface between the journal and the plain bearing. The contact angle should neither be too large nor too small. A contact angle that is too small increases the pressure on the plain bearing, which can cause significant deformation, accelerate wear, and shorten service life in severe cases; a contact angle that is too large affects oil film formation, preventing effective hydrodynamic lubrication. Experimental studies show that the limit contact angle for plain bearings is 120°. When wear reaches this contact angle, hydrodynamic lubrication fails. Therefore, under conditions that do not compromise the compressive strength of the plain bearing, a smaller contact angle is preferable. Theoretical analysis of friction torque indicates that the friction torque is minimized when the contact angle is 60°. Therefore, it is recommended that for plain bearings with speeds above 500r/min, the contact angle should be 60°; for plain bearings with speeds below 500r/min, the contact angle can be 90° or 60°.

STRACK bearing usage precautions

Plain bearings involve surface contact, so a certain oil film must be maintained between the contact surfaces. Therefore, the following issues should be noted during design: 1) Ensure the oil film can smoothly enter the friction surface. 2) Oil should enter the bearing from the non-load-bearing zone. 3) Do not place a full-circle oil groove in the middle of the bearing. 4) For split bearings, cut oil grooves at the joints. 5) Ensure the oil ring supplies oil sufficiently and reliably. 6) Do not block the oil filling holes. 7) Avoid forming stagnant oil zones. 8) Prevent sharp edges and corners that could cut the oil film. Plain bearings can also be lubricated with grease. When selecting grease, consider the following points: 1) When the bearing load is high and the speed is low, select grease with low penetration; conversely, select grease with high penetration. For high-speed bearings, select grease with lower penetration and good mechanical stability. Note that the viscosity of the base oil in the grease should be relatively low. 2) The dropping point of the selected grease should generally be 20-30℃ higher than the operating temperature. In cases of continuous high-temperature operation, ensure that the permissible temperature range of the grease is not exceeded. 3) When plain bearings operate in water-splashed or humid environments, select calcium-based, aluminum-based, or lithium-based greases with good water resistance. 4) Select grease with good adhesion.

Weidou Intelligent Technology professionally sells German STRACK plain bearings, STRACK rolling bearings, STRACK spherical plain bearings, STRACK deep groove ball bearings, STRACK angular contact ball bearings, STRACK self-aligning ball bearings, STRACK thrust ball bearings, STRACK double-direction thrust angular contact ball bearings, STRACK combination bearings, STRACK thrust roller bearings, STRACK needle roller bearings, STRACK insert ball bearings, STRACK self-aligning roller bearings, STRACK flanged bearings, STRACK linear bearings, all original imports from Germany. Welcome inquiries and orders.