Graphite Oilless Bearing On Large Crane

Oilless bearings are composed of metal substrates and solid lubricants embedded in the friction surface in proportion to a certain area. In the process of friction, the metal base material supports the load, and the solid lubricant embedded in the friction surface forms a layer of solid lubrication medium layer to achieve the lubrication effect.

Graphite Oilless Bearing On Large Crane
Graphite Oilless Bearing On Large Crane

Large Cranes Solution

Oilless Lubrication | Large Cranes Bushing & Pin

Given the demanding operational environment of large cranes, which involves heavy loads, high temperatures, dust, and frequent use, traditional lubricating grease struggles to stay on the sliding friction surfaces. This creates challenges for the bearings, especially at the connection between the upper pin shaft of the gantry plate hook and the shaft sleeve. Despite having an oil hole in the center of the pin shaft for periodic greasing via a centralized lubrication pump on the gantry frame, the extreme heat from molten steel often bakes the grease, causing it to dry up, carbonize, and form stubborn deposits. Consequently, maintaining proper lubrication becomes challenging. This particular component experiences minimal movement but faces significant pressure, making it hard to establish a consistent oil film on the bushing. As a result, dry friction occurs between the bushing and the pin, impeding the normal swinging motion of the hook.

Traditionally, manual oil application on the bushing’s surface was relied upon, but the harsh operational conditions—high temperatures, heavy loads, and dust—quickly displace or dry out the oil film. Additionally, steel slag residue on the lining’s surface contributes to roughness or cracking. To address these challenges, the VIIPLUS graphite oilless bearing, featuring a blend of graphite lubricating material and polymer organic material, proves to be highly effective in practice.

Requirements for solid lubricants

1. Oilless bearing can continuously provide lubrication to the friction surface.
2. The formed solid lubricant medium layer has a low friction coefficient. During the friction process, the blended material has the properties of releasing (or escaping) and reducing friction. It has a certain adsorption effect on the surface oil film.
3. Graphite plugged bronze bushing has certain heat resistance, corrosion resistance, and good compatibility with foreign objects.
4. Brass oilless bearing should have a thermal expansion coefficient not lower than that of the metal base material. When the temperature of the friction surface rises, due to its high thermal expansion coefficient, the friction surface will protrude, so that it can contact the counterpart and continuously provide lubrication.

Graphite Oilless Bearing On Large Crane
Graphite Oilless Bearing On Large Crane

Self Lubricating Bronze Bushing Mosaic Technology

How to make a self-lubricating bronze bushing? First, the various materials of the solid lubricant are mixed and stirred in a certain proportion and pressed into a cylindrical shape. Scribe and drill holes in the bushing metal base so that the embedded solid lubricant accounts for 25 to 35% of the total friction surface area. The formed solid lubricant is then embedded directly and combined with a binder to bond to the substrate by natural curing. Finally, the graphite bronze bushing is finished.

Self-lubricating bearings can be used more than a few times the normal copper sleeve period, used in the parts that are not easy to replace or grease is difficult to lubricate the occasion. Such as robot joint bearings, bearings used in aerospace vehicles, in vacuum conditions or high temperature, low temperature, and other extreme environments that need to be used for a long time is not easy to replace the bearing.

Tin Bronze Bushing VS Graphite Plugged Bronze Bushing

1. The load-carrying capacity of tin bronze bearings increases with the increase in speed, while the opposite is true for graphite-plugged bronze bearings. When the critical speed is exceeded, higher load-carrying capacity can be obtained by using tin bronze bearings. Therefore, graphite inlaid bearings can work well for the bushings of the shaft sleeve of the plate hook part with low speed and heavy load.

2. When the PV value of the tin bronze bearing exceeds a certain limit during operation, the temperature rises sharply, and it is easy to produce glue. The temperature rise of graphite inlaid bearing is lower than that of tin bronze under high PV value, so it can operate normally under high PV value, which also shows that the inlaid bearing has high-temperature resistance.

Graphite Oilless Bearing On Large Crane

3. Graphite plugged bronze bearing is different from tin bronze. When wear debris and residues accumulate on the bearing surface, under certain pressure and temperature, these residues will mix with the grease applied on the surface and stick to the surface of the solid lubricant, so that the friction surface of the lining is not directly connected to the surface of the solid lubricant. The friction of the paired parts reduces the wear on the surface of the lining.