Slide bearing operating condition affects melt pump operating efficiency

The better working condition of the sliding bearing of the melt pump should be that the driving shaft and the inner surface of the sliding bearing can form a layer of relatively uniform liquid film, the liquid film can separate the shaft and the sliding bearing 2 metal surfaces completely, the liquid film will play a role in supporting the shaft load. When the melt pump stops running, the journal will be in the lower part of the sliding bearing, the two metal surfaces are in direct contact, the gap between the shaft and the bearing is not lubricated with melt, and the bearing is in dry friction at the beginning of the startup.

thermoplastic melt pump

When the conveyed melt is increasing, the outlet pressure increases gradually, under the action of the pressure difference between the outlet and the inlet, part of the melt enters into the bearing gap by the guide groove, with the uniform rotation of the shaft, the shaft and the bearing surface will form a kind of melt formed by the thin film, at this time, the friction between the two metal surfaces is gradually reduced. When the melt film completely supports the vertical load of the rotating shaft, the frictional resistance of the bearing is only the viscous resistance of the melt, which is close to the state of liquid lubrication, and the friction factor of the two metal surfaces will reach the ideal state. Therefore, it is impossible to reach the ideal lubrication state under the finite load.

plastic extrusion melt pump

Sliding bearing failure form, mainly abrasive wear and adhesive wear. The higher the outlet pressure of the melt pump, the greater the shear force of the shaft on the lubrication film, the more serious the lubrication film damage will be, the closer the bearing area to the mixed friction, and even sometimes in a dry friction state, for the driving shaft and bearing surface damage is also the more serious. Shaft and sliding bearing inner surface wear close to the thickness of the hardened layer, do not simply once scrapped, (you can re-polish the shaft once again to use) but only need to replace a new set of sliding bearing, because the price of the shaft is a few times the price of the bearings, in this way, you can make the life of the pump shaft is prolonged.

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