Suffering from regular bearing failures on a feed conveyor at an animal feed production plant, the company´s maintenance team contacted NSK to see if the issue could be resolved. The investigations conducted by the expert team of specialists at NSK not only revealed the underlying cause of the problematic failures, but generated cost savings of over €13,000 for the plant, thanks largely to the elimination of machine downtime. An animal feed production plant is saving over €13,000 after adopting NSK Self-Lube Triple-Lip Sealed Bearing Units.
NSK´s investigations attributed the conveyor bearing failures to the ingress of hard particulates and moisture from process materials. As a result, it was recommended that the UK-based animal feed plant replace the standard self-lubricating units with Self-Lube Triple-Lip Sealed Units from NSK.
Since installation, the bearing units have been operating successfully for one year, which is in marked contrast to the previous situation whereby standard bearings required replacement every four months on average. These failures led to substantial downtime and costly loss of production. Now that these costs have been eliminated, and considering that fewer bearings are required over the course of a year, the annual cost savings for the plant have been calculated at €13,309. In addition, there has been a notable improvement in productivity thanks to greater conveyor uptime.
NSK´s Self-Lube Sealed Units feature a nitrile rubber triple lip that is bonded to a protective pressed-steel shield. As a result, longer bearing life is achieved through superior seal performance. In addition, the bearing units provide extended re-lubrication intervals, which in turn greatly reduces maintenance costs and increases the productivity of machinery and equipment.
Self-Lube Triple-Lip Sealed Units offer simple implementation and represent a ready replacement for existing bearing units. They are available for both set-screw and eccentric locking collar insert options. A large size range is offered, in both metric and imperial specifications.
NSK Self-Lube bearings help food plant save over €54,000 a year
As a result of pillow block bearings that were failing every six weeks on the multiple-belt dough-prove section of a process line, a UK-based tortilla wrap manufacturer turned to NSK for help. Investigations by NSK´s expert engineering team attributed the failures to the ingress of flour particulates and set-screw loosening (shaft creep) due to vibration. A recommendation was subsequently made to replace the tortilla wrap manufacturer´s standard pillow block units with Self-Lube Triple-Lip Sealed Units and eccentric locking collars from NSK. The replacement bearing units have successfully extended operating life from six weeks to over one year, resulting in significant cost savings. Flour particulates can be extremely damaging to incorrectly specified bearings on dough-prove belt conveyors
The dough prove at the tortilla wrap manufacturing plant has 42 rollers in total, which prior to the NSK recommendation were each supported by two pillow-block bearing units with a single lip seal and set screw locking arrangement. Rotation speed is around 120-rpm. A belt is wrapped around the rollers to convey the tortilla wraps and retain them for long enough to prove. The tortilla wraps travel from one end of the dough prove, flip over on to the belt below, and travel in the other direction. This sequence is repeated until they enter the oven for baking. Dough-prove conveyors operate in harsh conditions where they are exposed to flour particulates and metallic debris from chain and sprocket wear (a number of rollers on dough-prove conveyors are typically driven by sprockets and chain). For the tortilla wrap manufacturer, this operating environment meant that two mounted bearing units and one 35mm diameter shaft required replacement approximately every six weeks. The bearings were reported as damaged beyond use due to heavy contamination and creep damage to the bore, while the roller had to be replaced due to an undersized shaft diameter at the bearing fitting surface (from wear damage caused by creep). Every failure would require a significant number of man hours to perform the replacement, and bring about substantial machine downtime and costly production losses. In contrast, the introduction of NSK Self-Lube Triple-Lip Sealed Units has produced zero failures over a 12-month period. These bearing units feature a nitrile rubber triple lip that is bonded to a protective pressed-steel shield. As a result, longer bearing life is achieved through superior seal performance. Additionally, the bearing units provide extended re-lubrication intervals, which in turn greatly reduces maintenance costs and increases the productivity of machinery and equipment. In total, the annual savings at the tortilla wrap manufacturer have been calculated at €54,665. Self-Lube Triple-Lip Sealed Units offer simple implementation and represent a ready replacement for existing bearing units. They are available for both set-screw and eccentric locking collar insert options, in metric and imperial bore sizes. Importantly for the application at the tortilla wrap manufacturer, the selection of eccentric locking collars successfully reduced insert loosening in service, without damaging the shaft.
Plain bearings manufacturers offering only one product
Choice is good. Choice is healthy. Having options allows us to select the most relevant, the most efficient, the most cost-effective, the most attractive, the most compatible option. A “one size fits all” approach is rarely auspicious unless one is purchasing a pair of socks. Sartorial convenience aside, choice is what people want. We want to be presented with options and make our own decisions based on what is best for us. This is particularly apt in the bearings industry today. Choice allows businesses to select the most efficient solution for their specific projects. Manufacturers who are able to provide their customers with a range of products and provide unpartisan advice on the best product range for a given application are surely much more relevant than those who restrict themselves to one material and attempt to “shoe-horn” it into applications where something else is more suited? Here Craig Clydesdale explores the benefits of product choice and the folly of manufacturers who restrict themselves to just one.
Since the very first bearing was patented by the British inventor Philip Vaughan in the 18th century, plain bearings have been made from a multitude of materials to suit a vast range of applications. Typical materials have been wood, bronze, steel/composite, ceramic, glass, sapphire, plastic to name but a few. The list is endless.
Today the most prevalent materials are bronze, metal composites and plastic. Each of these materials has its own unique characteristics which lend them to being more suitable than others for certain applications.
For example; sintered bronze bearings are durable and have good load bearing capabilities, are impregnated with lubricant, can withstand high temperatures, run at high speeds and have excellent corrosion resistance. Hard rolled bronze bearings are durable and can take high loads, can withstand high temperatures, need lubrication and can run at medium to high speeds and have excellent corrosion resistance. Plastic bearings have good sliding properties, are limited on load and temperature and are not good when subjected to high loads when stationary for long periods. They do have excellent corrosion and chemical resistance.
Steel composite bearings mostly are of the wrapped type are usually self-lubricated, can take high loads, can withstand high temperatures and can run at medium to high speeds. Exposure to corrosion needs to be addressed.
Everything in its place
On all projects, multiple considerations are made regarding the bearing application conditions and just what is the best solution to handle such conditions. Temperature, load, lubrication, contamination, speed and interval of use are just a few of these considerations. After these application deliberations, regard needs to be paid to things like ease of maintenance, lubrication and unit cost. The luxury of being able to choose the precise material that will be able to withstand application conditions, lends itself to easy maintenance (or indeed no maintenance) and come within budget is not only convenient but indeed vital to the success of the overall project.
Lets take the purely hypothetical scenario of the installation of a retractable roof onto a sports stadium: The project manager approaches a very reputable manufacturer to install the bearings on the roof. However, this manufacturer can only offer one type of material. Whilst this material is perfectly suited for an array of applications across many industries, the extreme load of the stadium roof causes the bearings to deform after a period of inactivity and the roof to jam the next time it is activated. At great cost and embarrassment, the project manager now needs to remove the previous bearings and approach a supplier who can offer a more suitable material for this bespoke project. This example, whilst hypothetical, is extremely relevant today. Different applications will always require different materials. There is no “one size fits all” range of bearing that is suitable for all applications. If we go back to our clothing analogy for a moment; it is obvious that leather is a fantastic material for all manner of apparel, but there are more appropriate materials when a manufacturer is producing shirts or hosiery.
The point that should to be seriously addressed by engineers and buyers is the need to ensure that when enquiring of manufactures or suppliers, that they do not receive biased advice especially from companies that can only offer one range of product. The “one type fits all” claim can lead to serious design problems and ultimately failure in the field.
Manufacturers who can offer plastic, bronze, steel and composite materials etc. are able to look at each individual project with unbiased eyes. They are not slaves to a particular material and are therefore able to make impartial recommendations as opposed to manufacturers who erroneously state that one range can “do it all”. For the peace of mind to know that you have the correct bearing solution for your project, it is always best to speak to a supplier who can give you a choice of materials.
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