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.
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.
Established 100 years ago, NSK (Nippon Seiko Kabushiki Kaisha) is a Japanese-listed company that has evolved from a regional ball bearing supplier to a roller bearing specialist and automotive supplier with a global market presence. Today, NSK employs more than 31,860 employees in 30 countries. As per March 2018 NSK achieved a turnover of 1020 billion Yen. This result has been driven by ever-increasing investment in research & development, enabling the company to continuously improve the quality of its products and services. This investment supports NSK’s objective of “No. 1 in Total Quality”. In addition to a complete rolling bearing portfolio, NSK develops and manufactures precision components and mechatronic products, as well as systems and components for the automotive industry, including wheel bearing units and electric power-steering systems.
In 1963, NSK’s first European subsidiary, Düsseldorf, Germany, was opened and in 1976, the first European production facility in Peterlee, England. Today, NSK Europe supports pan-European sales with production locations in England, Poland and Germany, logistics centres in the Netherlands, Germany and England and technology centres in Germany, England and Poland. In 1990, NSK purchased the UPI Group including the renowned European bearing manufacturer RHP, with its factory in Newark (UK). Additionally, NSK has developed a comprehensive network of authorised sales distributors. NSK Europe is divided into application-based business divisions: Industry rolling bearing technologies & linear and precision technology (EIBU) as well as bearing modules and steering systems for the automotive industry (EABU & ESBU). In this organisation, NSK Europe\’s 3,900 employees achieved a turnover of over 1,056 million Euros as per March 2018.
For more information, visit www.nskeurope.com
NSK Deutschland GmbH
Phone : +49 2102 4810
Fax : +49 2102 4812290