Information Library: Newsletters

January 2013 Newsletter

National Precision Bearing Doubles Cleanroom and Relubrication Capacity

Preston, Washington – January 2013 - National Precision Bearing is excited to announce the opening of a new ISO Class 6 (Class 1000) cleanroom facility. This new facility more than doubles NPB's capacity for bearing relubrication services. The additional space and new equipment will make it possible to meet increasing Aerospace, Defense, Medical, and Food Processing industries' demand for specialty bearing relubrication. NPB relubricates new parts from inventory to meet special lubrication and fill requirements on standard parts, as well as customer owned inventory to help manufacturers and other distributors meet shelf life and on-hand inventory requirements.

"We have more than doubled our capacity for relubrication to match ever increasing demand. With the support of our bearing suppliers, NPB fills a critical need in this market. Our new facility ensures our lead time on new orders cannot be beat", notes Kent Ross, Mechatronics' President.

The cleaning and relubrication process at NPB is audited and certified by both customers and 3rd party inspectors. Among other standards, the cleanroom facility is certified to ISO 14644-1, 14644-2 and the entire process is included in National Precision Bearing's AS9100 Rev. C certified quality system. National's cleanroom is also factory certified for lubrication by major bearing manufacturers such as NHBB and RBC. Complete traceability and documentation is available for all orders. In addition to quality, the cleanroom staff consists of National Precision's most experienced supervisors and technicians, with over 150 years of combined relubrication experience.

NPB stocks a wide variety of specialty lubricants including food grade, low outgassing, and corrosive resistant greases. NPB has over 100 different lubricants in stock and regularly relubricates bearings with customer provided lubricants. Standard or special lubricant fill rates can be requested depending on type of bearings. Standard fill for miniature ball bearings is 25-35% fill, standard fill for many airframe type bearings is 80-100% fill. Grease Plating, centrifuge, and other special application methods are available on request.

The NPB website has added a detailed relubrication service brochure that further explains the capabilities and lubricants provided by National.

Tom Koetje,
Marketing and Business Development

Windsor L-245X
–65 to +300
  • Light general purpose oil.
  • Low torque.
Beacon 325 Synthetic
–65 to +250
  • General purpose grease.
  • Low torque.
Royco 27
–100 to +275
  • Corrosion resistant.
  • Heavy loads and high speed.
Rheotemp 500 Synthetic
–65 to +350
  • Oxidation inhibitor.
  • High temperature and high speed.
Mobil 28
–65 to +350
  • Low torque.
  • Low speed oscillation.
SRI-2 Mineral Grease –20 to +350
  • Long life. Water resistant.
  • High speed and high temperature.
Krytox 240AC Fluorinated
–30 to +550
  • High temperature.
Multitemp SRL Synthetic
–40 to +300
  • Very quiet.
  • Low torque.
Braycote Micronic
Polyether Grease
–112 to +400
  • Low pressure/vacuum environments.
  • Hostile chemical environments.
Aeroshell 33
Synthetic Grease -100 to +250
  • Corrosion resistant.
  • Heavy loads.

Can My Expired Airframe Control Bearing Inventory Be Saved?

Imagine you are tracking right ahead of a tight deadline for production. Your machined components stock-in, the bearings are pulled from stock for assembly, and a technician on the line discovers some of the bearings have exceeded recommended lube life. Now what? With new bearings at 20-30 week lead times, buying replacements is a problem. Fortunately, NPB can relubricate many types of bearings with a very short turn-around time. Read more about airframe control bearings, their shelf life, and common considerations for relubrication.

Airframe control bearings are a category of bearings generally designed for use in heavy load, oscillatory applications on aircraft flight control systems. These bearings are often full complement, meaning they have no separators between the balls, so they are generally not designed for high speed rotation. The industry specification covering the largest number of airframe control bearings is SAE-AS7949. Some of the most common airframe control bearing part number specifications are MS27641 and MS27646.

MS27640 KP( )
MS27641 KP( )A
MS27642 KP( )B
MS27644 DPP( )
MS27646 B500DD
MS27647 DW( )
MS27648 KP( )BS
MS27649 AW( )AK
MS21428 MB500DD

Shelf life for airframe control bearings is often limited by the lubricant, which is most commonly grease. Lubricant shelf life in a bearing is commonly defined by a manufacturer's guideline, a government specification, or industry standards. Shelf life for the most common AS7949 standard is 36months. If a bearing exceeds the 36month shelf life, it often cannot be used or installed into an aircraft. However, a bearing exceeding its recommended lube life does not mean it must be thrown away. Many manufacturers, distributors, and repair stations are forced to hold inventory for more than three years. Writing down or throwing away this expired inventory can result in significant losses of value. A good and viable solution is to have these bearings re-lubricated by an AS9100 re-lubrication facility that maintains factory authorization.

Click here to see NPB's Factory Authorizations

Many common airframe control, needle, metal-on-metal spherical, and rodend bearings can be relubricated or refreshed. Some cannot, like self-aligning stake shielded, or ball bearing rodends, due to their design features. Those, if they can be relubed at all, should be done by the manufacturer. The most common types that can be relubed are listed in a table below this article.

Some bearings for aircraft applications allow for lubricant to be refreshed or additional lubricant to be added through a lube hole or grease fitting. In some cases, aircraft bearings cannot be washed or old lubricant cannot be purged. In this case, the relubrication can be provided as a "refresh" depending on customer requirements.

If you have an expired part and would like to know if it can be relubricated, please contact your NPB Sales & Marketing Rep or Regional Sales Manager with the bearing specification, drawing, or a picture of the part. For more information contact your local sales representative.

Melody Dazey,
Aircraft Product Manager