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The bearing selection procedure is a step-by-step process of answering a series of questions:

  1. What type of bearing is needed?
  2. What are the loads and speeds of the application?
  3. What is the operating environment?

Unfortunately, there are some instances in which a designer is unable to definitively answer one or more of these questions. This dilemma results in the decision to select a standard bearing – a safe and quick choice. In many instances, the standard bearing will work well and yields an appropriate outcome. In others, it results in a bearing that is more expensive than necessary.

A standard bearing almost always exceeds the functional needs that the application requires, as they are designed to operate in a range of products and are necessarily manufactured to carry heavy loads and run at high speeds and tight tolerances. The result is a bearing that is overspecified and costly.

A cost-effective alternative to an over specified standard bearing is a custom bearing. Custom bearings can be sized to an application’s specific needs, which improves the assembly process and boosts product quality.

The following are six considerations to take into account when specifying a bearing to meet a project’s cost and performance requirements.

1. Select the Bearing Type

The type of bearing needed is defined by the direction of the load in the application. Thrust bearings support axial loads; radial bearings support radial loads; and angular contact bearings support loads that are a combination of radial and axial.

2. Define the Loads & Speeds

Custom bearings can be designed to carry loads from ounces to tons and accommodate lower or higher speeds, depending on the application. The next step in creating a custom bearing is defining these factors as closely as is practical. The combination of load and speed All image credit: National Bearings Companyhelps determine the most appropriate style of bearing.

The uncertainty of load and speed in the application is often the factor that prompts the product designer to default to a standard bearing. However, the safety factor that is inherently built into a standard bearing often has expensive consequences that impact product design.

Custom bearings can be properly sized to fit the actual demands of the application. Dependent on load and speed of the application, bearings can be designed with the right number of rolling elements or by using races that have unique diameters or widths. That means a housing or mount can be designed for a bearing that is smaller and less expensive. It can also mean that an adapter does not need to be added to fit a shaft or spindle to a standard bearing bore.

3. Consider the Operating Environment

Environmental conditions must be addressed to ensure proper product operation. A standard bearing can fail prematurely or might require extraordinary protection to function reliably for the life of the application.

  • Corrosion – Will the bearing be exposed to salt water, sunlight, or chemicals that might quickly destroy a standard bearing? Choosing an appropriate material such as stainless steel or an engineered plastic resin can mitigate the corrosive effects.
  • Temperature – Will the bearing experience extreme temperatures or temperature changes during operation? Selecting materials that do not change dimensionally or deteriorate in extreme conditions is critical.
  • Contamination – Will the bearing need to be protected from contamination or can it be designed to resist fouling? Dust, body fluids, and abrasive materials can destroy or compromise even the toughest standard bearings. Selecting the appropriate lubricants or designing bearings that do not require lubrication can dramatically improve bearing performance

4. Can the Bearing Do More than Just Rotate?

Selecting a standard bearing requires the product design to submit to the constraints of the bearing and limits design freedom. Opportunities to optimize the other components in a design are sacrificed for the sake of fitting the bearing into the design. A custom bearing can do more for a product than merely rotate – it can set a design free to do more.

  • More Compact – Standard bearings often contain components that are not necessary to product functionality. A custom bearing can be simplified to eliminate unnecessary components. A product might only need a thrust retainer rather than a complete thrust bearing, or a roller bearing might not need an inner race.
  • More Features – Only a custom bearing can be designed to incorporate additional features that can simplify assembly or improve functionality. A threaded mounting stud could eliminate a component in an assembly. A ratchet and pawl feature can create a bearing that turns in only one direction, produces an audible click to indicate position, and reduces the overall size of the product.
  • More Quality – A custom bearing can improve the way components work together from the outset. An adjustable threaded mount can be used to eliminate misalignment due to variation of other components.

5. Improve Assembly Productivity

A subassembly that includes a custom bearing and other components that work together in a product can dramatically improve assembly productivity. In some cases, components like bolts and adapters can be eliminated. In other instances, a subassembly that is ready to install in an assembly cell can improve throughput, reduce the number of parts inventoried, and help consolidate the supply chain.

Developing a custom packaging solution that presents bearings to assembly personnel ready to install, in the right quantities, and properly sized for the assembly area, can improve productivity and reduce the number of times that products are ferried from inventory to assembly cell and back again. Reusable and recyclable packaging can also be developed to reduce costs and waste.

6. Post-Production Strategies

Opportunities to improve the bearing specification process don’t stop at the product level. Inventory management assistance is another way in which the process can be streamlined to the manufacturer’s benefit.


This article originally appeared in the June 2015 print edition of PD&D.

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