Key points
Opinion is split….
Following a period of intense innovation using state-of-the-art 3D printing, the humble split roller bearing can now outperform solid bearings, and other leading split bearings for high-load applications like drives and electric motors.
Here, Ian Breeze, Technical Director for bearings innovator, Bowman International, explores what has changed in the world of split roller bearing design and why process industry engineers are so keen to switch:
In very simple terms, a bearing is a mechanical device that either guides or confines the motion of the moving parts in a machine. In doing so, the bearing reduces friction amongst components, improving the rate of wear and extending the working life of the equipment.
Split roller bearings in particular are renowned for their ability to improve efficiency – saving time during installation, inspection, and maintenance – particularly in applications where access to the shaft is limited.
Yet, despite being a stalwart of the manufacturing industry, split bearing design has remained relatively unchanged since they were first introduced in the early 1900s, but the applications they serve are changing all the time.
The pressures of modern manufacturing, not least the introduction of more automation and increasingly complex machinery has driven a need for bearing innovation for some time now but bearing manufacturers have had their hands tied due to a lack of appropriate innovation in material science and machining technology.
In other words, bearing manufacturers wanted to evolve the design of their bearings to meet the needs of modern industry, but simply couldn’t.
Now, finally, things have changed. The introduction of additive manufacturing (3D printing) has opened doors for leading bearing manufacturers like Bowman to create products that can meet the needs of increased production, more aggressive manufacturing environments, and applications with higher radial and axial loads.
Improving performance and reducing maintenance through correct bearing specification
One of the most common causes of bearing failure is incorrect specification. This is especially important when specifying bearings for high-load environments because if the wrong bearing is used, it may not carry the required load effectively, leading to damage and potential failure.
There are two main types of load. Radial load refers to the loads acting at right angles to the shaft, and axial loads are applied parallel to the shaft in both directions. While many bearings are designed to handle either axial or radial loads, high-load applications in heavy side industrial applications often require a combination of the two – a requirement that, due to limitations in manufacturing, has been left largely unmet.
To best serve the needs of high-load applications that have both types of forces in play, many bearing manufacturers and OEMs will use a combination approach – using a pair of bearings to accommodate the load in each direction.
The shortcomings of this method mean more space requirements within the machinery – increasing its overall footprint on the factory floor – as well as potential complications with both assembly and access for ongoing maintenance.
While there is an increasing number of bearings on the market that are designed to handle both radial and axial loads, they work by inclining the radial elements to give some axial capacity. In doing so, they trade off radial capacity for axial – a solution that limits the axial load capacity, limiting application usage or putting the bearings at risk of failure.
Both radial and axial load specifications directly relate to the strength and rigidity of the bearings, shaft, and overall machinery. Exceeding these specifications in an application with a high axial load may result in damage to the bearing and have a different impact on efficiency. In fact, studies suggest that exceeding either radial or axial load specifications by 10% may reduce the lifespan of the components by about 1,000 hours – as well as running the very real risk of unplanned downtime. For applications with a high axial load, these solutions are far from ideal.
Innovations in split roller bearing design for more effective load management and maintenance
Recent innovations in the manufacture of split roller bearings, and the use of additive manufacturing to create more complex component geometries, are allowing bearing manufacturers to accommodate axial or multidirectional loads as a primary consideration, extending system life and reducing downtime.
With no need to invest in expensive tooling, or set up traditional manufacturing production lines, it is possible to experiment with design features in a way that simply wasn’t possible previously. For Bowman, the technology has facilitated the creation of a bearing that offers a substantial increase in axial and radial load capacity, as well as increased durability, functionality and turnaround time.
In a standard split roller bearing design, the rollers run against the outer race lips and clamp rings on the inner race assembly of the bearing, creating stress, friction, and a lower tolerance for axial loads. Using engineering-grade 3D-printed Nylon-11 and the latest printing technology, the company has been able to create a bearing design that removes the axial locating lips from the bearing outer race. This means that the radial roller length, as well as the actual number of rollers, can be increased – giving a higher load capacity and an approximate increase of x5 radial L10 life.
1000% increase in axial capacity
By adding axial roller and cage assemblies to their design, Bowman has overcome the issue of reductions in axial load by using three sets of rolling elements to allow independent handling of the radial and bidirectional axial loads.
The design incorporates the usual benefits of a split bearing system – including bearing changes of up to ten times faster than solid bearings – while increasing the radial capacity by between 25%-75% and the axial capacity by 1000% compared to standard solutions.
In the UK, downtime costs manufacturers £180bn per year – arguably the biggest contributor to production and profitability losses. With bearings critical to the efficiency and operability of industrial machinery, investing in the right component for the job is a simple yet effective way of minimizing the likelihood of unexpected downtime.
For this reason, due consideration should be given to ensuring that bearings meet type and load capacity requirements, while also taking into account all important lifecycle costs and ease of installation and maintenance.
The ease of maintenance benefits to split roller bearings
Reducing downtime is an important driver in any industry, especially those with restricted system access, mission critical operational parameters or high levels of customer demand to meet.
It can be tempting to skip regular maintenance or cut corners to get equipment back up and running quickly, but this will only lead to further failures. Selecting bearings that offer easy installation and maintenance processes can keep downtime to a minimum and performance optimised.
Choosing split bearings over solid bearings for example can save time during installation and maintenance because they are assembled radially around the shaft. This eliminates the need to disconnect the coupling and move other equipment, such as motors, gearboxes or pumps out of the way to access the shaft – making installation up to ten times faster.
The Bowman Advanced Split Roller Bearing in particular even uses the rollers to lock the two cage halves together, eradicating the use of small and easy to lose clips and other locking components. Further enhancing the performance of this revolutionary split roller bearing is a patented triple labyrinth seal which not only offers a tighter seal than other split bearings, but also reduces the need for costly removal, machining or replacement of worn shafts.
When a shaft becomes worn, engineers can simply fit a new extended seal covering the undamaged part of the shaft, without compromising performance and without the need for extended downtime.
These particular split roller bearings are even dimensionally interchangeable so that they can be retrofitted directly into existing competitors bearing housings so that maintenance engineers can quickly and cost-effectively improve radial and axial load capacities.
For highly corrosive environments, selecting the right bearing can significantly reduce maintenance and downtime. It is always tempting to simply re-specify the split roller or solid bearings that have been used for many years, but staying up to speed on bearing innovation, and following the trend towards advanced split roller bearings can lead to real time, cost and performance benefits.
To find out more about how switching from your existing split or solid bearings to advanced split roller bearings could benefit your facility, search ‘bowman split bearings’ online.
