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It takes a lot of expertise to select a full bearing or even the particular retainer within that bearing for best product performance. Find out why a distributor can often be of more assistance than a bearing factory engineer.

  It is commonly thought that working directly with a factory engineer is the most direct approach to solving a bearing design problem.  But is it?  Unless the engineer has exactly the relevant expertise needed, you might be better off with another engineer, manufacturer or another bearing type. A good distributor, with their broader experience and perspective on bearing solutions, could offer you access to the wide range of manufacturers throughout the world for the optimum solution.

  The consequences of not considering all pertinent factors in bearing selection are sometimes severe. For instance, focusing only on performance and reliability, without considering price and availability, can result in a product too costly to produce.  Alternatively, specifying a bearing that meets a target cost, without verifying reliability, can lead to disaster when a product, such as a medical device, goes to market. The factors that must be considered include: performance, reliability, service life, source country, availability and price.

  Consider a recent example I was made aware of. A company's product design team had worked with a bearing factory engineer to specify a bearing for a pump in their medical device. Having the application description, the bearing engineer recommended a bearing that was being used in a pump for an aircraft application. Once the product went into pre-production, the design was re-reviewed for costs and the bearing was identified as costing nearly 50 times the cost of a different bearing used on another pump made by the same company. The aircraft bearing was probably second to none in performance and reliability, but was extremely costly and had prohibitively long lead times, the alternate bearing not only met the performance and reliability requirements but also the price and availability needs of the application. The evaluation process and work required to change the design to incorporate the other bearing added significant engineering time and expense.

  As a distributor, National Precision Bearing, has over 200 years of bearing selection and specification experience  NPB offers its customers direct access to the deep knowledge of its vendors and their engineering teams, as well as a broad range of application based solutions. For the success of your product, it’s vital to focus on all factors in the product selection process. NPB can help your company make sure that happens. Once a requirement is defined, NPB will work with a customer and the factory to create a complete sourcing solution leading to a reduced total cost of design and procurement.

  If you would like input on your next bearing design project, or need help finding less costly alternatives for a bearing in an existing design, contact your NPB Field Sales Representative today.

Tom Koetje, Manager of NPB Products

Selecting the correct retainer plays a critical role in determining the successful performance of a precision ball bearing.  The retainer, also known as a cage, is the bearing component that separates the balls and maintains their symmetrical radial spacing.  Many factors must be taken into consideration when making this important decision.  Depending upon the application, cages can be selected to meet torque, load, speed, temperature, and even lubrication requirements.  Many cage designs have been developed to meet a wide range of requirements.   Here are some of the more common ones......

The most common precision ball bearing retainer is the two piece stamped and crimped metallic ribbon retainer made of stainless steel.  This design is a closed pocket design with loosely clinched tabs, which helps prevent cage windup in sensitive low torque applications.  It’s used on radial bearings.  The ribbon retainer is advantageous due to its’ high durability and low starting torque.  It is also inexpensive and used for most general applications.  The ribbon retainer is best suited for lower speed applications under 90,000 dN (bore mm x rpm).  

   Another standard retainer commonly used is the one piece stamped crown retainer.  This stainless steel retainer has coined ball pockets and polished surfaces which result in a smooth low-friction contact surface for the balls.  The crown retainer is used on radial bearings due to its’ smooth running and slightly higher speed capability than the metallic ribbon retainer.  The stamped crown is inexpensive, lightweight, and also used on most general applications.       

For higher speed applications, a machined crown retainer was developed.  The machined crown retainer is used on radial bearings for speeds reaching up to 1,200,000 dN.  This retainer can be made from several different types of materials depending upon the application’s requirement.   These materials include paper or linen based phenolics, and polyamides.  Both phenolic materials can be vacuum impregnated with oil, allowing for better lubricity within the ball pockets.  The polyamide materials contain small amounts of graphite and PTFE, which aid in lubricity as well.  The polyamides also have the added advantage of being fully autoclavable, which makes them well suited for medical and dental applications.  Phenolic retainers are typically used on medical, machine tools, aircraft instrument, and high speed motor applications, while polyamides are used on medical, dental, and high temperature applications.

For ultra high speed applications, a machine full type retainer is recommended.  This retainer is only used in angular contact bearings.  The balanced and symmetrical design of the full retainer allows it to achieve speeds of up to 2,000,000 dN.   This retainer is also built from either the phenolic or polyamide materials which allow it to have the same advantages as the machined crown retainer.  The machine full type retainer is often used on machine tool spindles, high speed motors, dental, aircraft instrument, and medical applications.

There are many factors that must be taken into consideration when deciding upon the correct retainer for a bearing.  Each retainer has its’ own distinct advantage which make it suitable for a particular application.  If you need help in deciding, you can ask your technical sales specialist at National Precision to help determine which retainer would work best for you. 
John Meneses, Miniature Product Manager

  The end of 2009 and beginning of 2010 has seen a considerable increase in the actual throughput of our re-lube service. In an average month at NPB, nearly 200,000 bearings are processed in our class 1000 re-lubrication facility. December’s total was 176,300 and January was in excess of 318,400 pieces. A growing number of customers have found NPB as a reliable source for bearing preservation and re-lubrication. If you have a question about bearing re-lubrication or need a quote, please contact your technical sales specialist.

Tom Koetje, Manager of NPB Products

As you see, price isn't everything, but availability of the correct bearing with the correct component parts is something National Precision Bearing can provide.

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