The Reliability of Spiral Roller Bearings

Bearing components act as elastic bodies under load. They can sustain cyclic strain but must be kept cool, clean and properly lubricated to avoid general material fatigue.

The p-factor model predicts that bearing life will decrease to the cube of the ratio between rated load and actual load. Bearings are therefore designed to be operated within their rated load capacity.

Stability

Unlike ball bearings, these are not very sensitive to temperature. The spring steel used in these can withstand high temperature, and it is less sensitive to corrosion. This makes it more suitable for use in a variety of different applications.

They can also resist the cavitation that occurs when there is a lack of sufficient lubrication between the working surfaces. This is because the spiral grooves provide a sufficient amount of pressure to keep the working surface lubricated and separate.

This type of bearing is also durable and is resistant to dirt, iron filings, water and hydrophloric acid. The thin-walled bushings also leave a large space for larger-diameter rolling parts, which can squeeze the dirt and foreign matter out of the gap as they rotate. This makes the spherical roller bearing an excellent choice for use in the running and support rolls of milling machines. They are also suitable for the centre and caster rollers of casting and drawing equipment.

Reliability

Inherent reliability of spiral roller bearings is achieved through their special herringbone pattern of grooves. The symmetrical herringbone pattern has zero flow, reducing the risk of entraining dirt into the bearing. In contrast flat thrust bearings, journal, conical and hemispherical forms generate a constant flow of lubricant from the radial grooves through a constant restriction to transverse flow.

The herringbone pattern also allows for more grooves, increasing the load capacity of the bearings. It also reduces the frictional resistance to rotation. These characteristics make spiral roller bearings ideal for heavy radial loads.

Another reason that spiral roller bearings are so reliable is their ability to withstand severe misalignment. They are designed to work with a wide range of misalignment and are commonly used in harvesting machines, air-blowers and paper and textile machinery. They are also often found in cranes, woodworking equipment and power plants. They can handle both radial and axial loads with ease.

Load Capacity

Bearings support a variety of loads, including the weight of equipment and transmission forces such as gears. Moreover, they also bear shock vibration loads and other forces. Load capacity is often measured by how long a bearing can withstand the load without failure.

One of the most common causes of bearing failure is contamination. For example, particles such as dust and sand can become lodged in the bearing’s raceways and cause sharp indentations that increase friction. Over time, this can lead to surface fatigue, causing metal case fragments to break off from the raceways.

The lubrication of a spiral roller bearing is another important factor in its load capacity. Its spherically shaped outer ring allows for more deflection, and its rolling element arrangement ensures continuous and even distribution of lubricant across the working surfaces. It is also less sensitive to high temperature and can easily withstand mounting inaccuracies. This makes it ideal for use in steel applications, such as support and guide rolls in continuous casting and roller table rollers in furnaces.

Maintenance

Many factors contribute to bearing failure. Most bearing failures are caused by abrasion, fatigue or pressure-induced welding (CIW). Abrasion is the result of hard contaminants scraping away surface materials. Fatigue is a result of repeated loads and releases which eventually cause the material to deteriorate. CIW is the result of high contact pressure that causes surface melting and distortion.

Lubrication is a critical factor in bearing life. It is important to follow the bearing installation directions and service recommendations when re-lubricating the bearings. It is also important to use a compatible lubricant. Petroleum-based lubricants are common, but synthetic lubricants provide superior performance and can be used in high temperature applications.

Using an ultrasound system to monitor the condition of the bearings is an effective way to detect early signs of a loss of lubricant. When the ultrasound level increases by 8 dB or more, it is an indication that the lubricant is wearing out and that a replacement is needed.