Bearing Remanufacturing – The Basic Types Of Bearings Repairable

Bearing repair is not a new idea, nor has it evolved significantly over the years — which is good news. Repairing damaged bearings is a precise science that has been fine-tuned over time through gradual and careful improvements to provide superior results. As new designs and technologies improve bearings, growing expertise and technology in bearing repair continue to improve the reliability and performance of reconditioned bearings, making them a more cost-effective alternative to purchasing new bearings. Bearing remanufacturing can considerably reduce carbon emissions, using only about 10% of the energy required to manufacture a new one. By extending bearing service, remanufacturing prevents component scrapping and waste of natural resources. A remanufactured bearing will also have a shorter lead time than a new one.

Benefits Of Bearing Remanufacturing:

  • Lower life cycle costs
  • Improved service life
  • Machine downtime has been reduced.
  • Reduced environmental impact
  • Replacement bearings were kept on hand.
  • Increased overall asset dependability
Typical threats include wear, rust, solid particle contaminants, and sporadic metal-to-metal contact. Material fatigue may also occur as a result of shear stress appearing cyclically immediately beneath the load-carrying surface of a bearing’s rings and rolling elements. Such stresses cause micro-cracks beneath the surface to form over time, eventually extending to the surface itself. As the rolling elements of a bearing pass over the cracks, material fragments break away (this is known as “spalling”). For a bearing, this is usually the beginning of the end. When a bearing fails, it is certainly possible to replace the bearing. However, this standard approach can be costly and may involve lengthy delivery lead times. Using a controlled remanufacturing process for the bearing and then returning the bearing to full service, rather than outright replacement, offers a practical and cost-effective alternative.

Four Levels Of Bearing Repairs

Bearing repair is an exacting science that begins with an expert’s eye. A simple visual inspection kicks off a careful evaluation process that compares common types of bearing damage like scuffing and staining, to their repair potential. The extent of repair work can be determined once the type and extent of damage are determined. Serious damage may necessitate extensive rework, including the replacement of major components. Inspection and rework operations are classified into four levels. The following operations are listed in increasing order of repair time, difficulty, and cost:

Repair Type:

  1. Inspection, Cleaning, written report, and repack.
  2. Level I along with polishing all the components.
  3. Level I along with grinding rings plus manufacturing new rollers and cages.
  4. Level I + Level III + new inner and outer ring.
Bearing Repair
A detailed description of a typical Level III operation follows
  1. The complete cleaning of the bearing.
  2. Disassemble and inspect each component, etch the serial repair number, and record pertinent bearing information.
  3. Generate a written inspection report and formal quote.
  4. Launch a manufacturing order for regrinding races and producing new sets of rolls; generate routings and prints.
  5. Grind the raceways on the inner and outer rings until no surface damage remains.
  6. All other surfaces should be polished as well as possible without removing material from critical surfaces.
  7. Magnet Est and examine the inner and outer rings.
  8. The amount of material removed from the raceways, as well as the internal geometry, is used to size new rollers.
  9. Perform necessary cage maintenance.
  10. Grind rollers to the desired size.
  11. Rollers are magnets, inspected, and sized.
  12. Check clearances before assembling the bearing.
  13. Save, pack, and ship.
When to repair?
Despite its many advantages, reconditioning is not always the best option for a damaged bearing. The difficulty in properly utilizing bearing repair services is determining whether or not a bearing requires repair and deciding which options are the most cost-effective and long-term. Visual inspection is the first step in determining whether a bearing requires repair. A thorough examination of additional criteria, such as the following, aids in determining the need for repair:
  • Is the bearing beginning to reach or past its recommended life expectancy?
  • Have operating temperatures surpassed 200 degrees Fahrenheit?
  • Is the bearing subjected to excessive vibration?
  • Has the bearing been subjected to sudden lubrication or temperature changes?
  • Early detection of a problem via routine checks can save businesses unnecessary downtime and expense while also allowing them to capitalize on the capabilities and benefits of bearing repair.
Regardless of the manufacturer, type of bearing, or application, proper treatment can help to preserve and restore a bearing-to-like-new condition for continued use. Bearings with little or no damage can often be easily and cheaply reconditioned and recycled.

Bearing Restoration Best Practices

Rolling bearings are candidates for reprocessing (though small sizes may be economically unwise), and the nature and extent of restoration will hinge on the affliction of the bearing and the application requirements. In general, relevant functional surfaces of the bearing will be repaired during remanufacturing, including the replacement of bearing components as needed. Expert analysts should be consulted as a best practice. They will be well-equipped to evaluate the bearing and determine which remanufacturing method will be most effective in restoring the bearing. The recommendations and restoration work will then be guided by standard industry procedures and established criteria. Some bearings may require more attention than others. As a result, rework categories leading to remanufacturing have been developed. Inspection: This is the first step, whether for a used bearing or bearings that have been stored for a long time, and it involves comparing them to drawing and/or specification requirements. Cleaning, degreasing, and disassembling the bearing is typically followed by nondestructive testing, visual or microscopic inspection, and dimensional inspection, followed by a detailed bearing analysis report with recommendations for appropriate treatment and rework attention. Reclassification: This procedure includes all inspection operations as well as minor repair (buffing and minor polishing of inactive and active surfaces, as well as grinding of scratches and grooves), demagnetization, reassembly, dynamic testing, lubrication, preservation, and return to service packaging. Refurbishment: This service category is based on selected inspection and reclassification activities and includes one or more of the following tasks: replacing rolling elements, remanufacturing the bearing’s cage for the rolling elements or replacing it with an identical cage, exchanging used components (such as seals, snap rings, and others), grinding or polishing and/or plating of mounting surfaces to return the bearing’s outside surface and bore to original drawing dimensions. Remanufacturing: This set of tasks also included previous operations such as inspection, reclassification, and, if necessary, refurbishment. It will also include one or more of the following activities: grinding, ring installation, and changing or substituting components to create a different assembly identity (in effect, modifying in order to improve performance or properties). Deeper grinding of the inner and outer ring raceways of larger bearings is acceptable during remanufacturing. Furthermore, additional machining methods, such as hard turning, can be used. The surface damage is removed, and the stressed material volume is altered. The surface is finished in accordance with the original blueprint specifications. In some cases, new rolling elements with diameters greater than the original rolling element diameter may be designed. The increased size of the rolling elements may necessitate reworking or replacement of the cage pockets. Following completion of work, final inspection and measurements, cleaning and preservation, service reporting, and documentation archiving should be performed. NBC Bearings have many years of bearing remanufacturing experience A global network of specialists performs work at dedicated service centers that adhere to strict specifications. Bearings that are not irreparably damaged can be restored using suitable techniques such as polishing, grinding, and component replacement. In fact, any bearing that has more than 30% of its calculated service life left can be remanufactured. As a result, the cost savings that can be realized through remanufacturing are significant.