Archive for March, 2015

Global Energy Management System Certification Awarded to SKF

Friday, March 27th, 2015

SKF is a major worldwide provider of bearings, seals, lubrication systems, and services. With their nearly 50,000 employees, SKF is represented in more than 130 countries and has around 15,000 distributor locations worldwide.

Applying energy efficient practices enables organizations to save money together with helping to conserve resources and take on climate change.

Introduced in June 2011 through the Geneva-based International Organization for Standardization, the ISO 50001 standard is a global energy management system designed to continuously increase energy management performance, together with energy efficiency, energy use and conservation.

The ISO 50001 standard provides a thorough and clear approach to smart energy use, and enables companies and ships to reduce their energy consumption and make the most of renewable energy technologies.

ISO 50001:2011 provides a framework of requirements for organizations to:

  • Develop a policy for more efficient use of energy
  • Fix targets and objectives to meet the policy
  • Use data to better understand and make decisions about energy use
  • Measure the results
  • Review how well the policy works, and
  • Continually improve energy management.
  • Source: www.iso.org

In February of 2015, SKF was awarded a global certification by Den Norska Veritas (DNV), in accordance with the requirements of ISO 50001. A total of 38 manufacturing facilities around the world are using the innovative energy management system. In total, these facilities account for more than 90% of SKF’s total direct energy use.

Certification to ISO 50001 is not obligatory. Certain companies choose to carry out the standard strictly for the positive advantages it offers. Others elect to get certified to demonstrate to outside parties that they’ve implemented an energy management system. SKF pointed out that it is enthusiastic about improving energy performance from both an environmental and a cost perspective. The ISO 50001 standard aids in addressing these concerns in a well-organized, methodical and consistent way.

SKF implemented the ISO 14001 environmental management standard back in the 90’s and recently adopted the LEED standard for new buildings. The business also promotes the more expansive adoption of ISO 50001 among its energy intensive suppliers.

“We recognize our responsibility to significantly improve energy performance, which is motivated both from an environmental and a cost perspective. The new ISO 50001 standard helps us to address this in a structured, systematic and consistent way,” said Rob Jenkinson, Director, Corporate Sustainability. Source: skf.com

Sleeve Bearings – Design and Applications

Friday, March 20th, 2015

Today we are focusing on the design and applications of sleeve bearings. First of all, a sleeve bearing is a simpler type of bearing with few moving parts. Its name is derived from having a single internal rotating cylinder inside of it and an outer rotating sleeve. These two are the only moving parts of this type of bearing.

Sleeve bearings can be made of compressed powdered metal, such as bronze or copper. The material from which they are made makes them microscopically porous, meaning they will draw up lubrication when it is applied to the outer sleeve, making them sort of self-lubricating. I say sort of, because failures due to lack of lubrication still are common. The lubricant could become viscous through adverse temperature conditions, or there could simply be a lack of lubricant, which would eventually cause the bearing to cease movement – that’s not good!

Because of this, sleeve bearings are typically shielded from dust and dirt by elaborately designed seals. Mechanics and engineers must carefully select where a sleeve bearing will be located in a machine. Sleeve bearings are more finicky than ball bearings, because a ball bearing, given inadequate lubricant would wear down gradually over time, whereas a sleeve bearing stops altogether.

The sleeve bearing is a part of many everyday machines. Household appliances, fans, office machinery, and automobiles all employ sleeve bearings. Fans being the most common application. Sleeve bearings are less subject to extremes in humidity, and are considerably quieter than machines made up of ball bearings. If an application requires a low noise level, sleeve bearings are your go-to.

For example, as engineers race to build faster computer systems with more powerful microprocessors and compact designs, they are faced with the issue of too much heat for the components to remain functioning. In this case, they’ll look for a reliable fan that will cool and protect the device against a system meltdown.

Both ball bearings and sleeve bearings can be used in the axial fans these engineers will employ, but as previously mentioned, sleeve bearings are quieter, thus more consumer-friendly. Should the device need to withstand a long lifespan and endure extremely high levels of heat, then a fan with a ball bearing may be the answer.

Thrust Bearing Applications

Friday, March 13th, 2015

The thrust bearing is a type of rolling element bearing. Like other rolling bearings, they allow for rotation between parts, but are specifically designed to support an axial (rather than radial) load.

Generally, thrust bearings are composed of two washers, or raceways. And as opposed to roller thrust bearings, ball thrust bearings generally operate at higher speeds while accommodating lower loads. Also keep in mind that higher speed applications will require oil lubrication.

Thrust bearings varieties:

  • Thrust ball bearings – Composed of ball bearings supported inside a ring. These can be used in lower thrust applications, where the axial load is small. Barstools and lazy susan turntables use this type of bearing.
  • Cylindrical thrust roller bearings – Made up of small cylindrical rollers that are arranged flat with their axes pointing to the axis of the bearing. They give very good carrying capacity, and are generally cost effective, although they tend to wear due to the differences in radial speed and friction since it is higher than with ball bearings.
  • Tapered roller thrust bearings – Composed of small tapered rollers arranged so that their axes all converge at one point on the bearing’s axis. The length of the roller and the diameter and angle of rollers must be carefully calculated to provide the correct taper. This is so that each end of the roller rolls smoothly without skidding. They can support rather larger thrust loads than the ball type due to the larger contact area, but are typically more expensive to manufacture.
  • Spherical roller thrust bearings – These use asymmetrical rollers spherical in shape, rolling inside a house washer with a raceway that is a spherical inner shape. They can accommodate combined radial and axial loads and also accommodate misalignment of the shafts. These bearings also offer the highest load rating density of all thrust bearings.
  • Fluid bearings – Characterized by the axial thrust that is supported on a thin layer of pressurized liquid giving these a low drag.
  • Magnetic bearings – Characterized by the axial thrust supported on a magnetic field. This is used where very high speeds or very low drag is needed.

Thrust bearings are commonly used in automotive, marine, and aerospace applications. They are also used in the main and tail rotor blade grips of radio controlled helicopters.

Proper Bearing Handling

Friday, March 6th, 2015

As a precision part, a rolling bearing must be handled very carefully to keep its preciseness unchanged. Below are some handling instructions to adhere to in roller bearing handling.

Cleanliness: Foreign matters can cause harmful effects on bearing usage and life. To avoid this, the bearing and other parts that are mounted next to the bearing must be kept clean – as well as tools, lubricant, washing oil, etc.

Care: To avoid preventable defects caused by shock to a bearing, take care when handling the bearing. Any shock could result in surface flaws, indents on the raceway or rolling elements, and cracking or chipping.

Using proper tools: Be sure to use the specific tool required for installing and removing the bearing, as opposed to something uncalled for. This is especially important for when installing a drawn cup needle roller bearing.

Protection from rust: There is a rust preventive oil coating on all bearings, however, handling bearings with bare hands can cause rusting. Wear gloves to avoid this issue, or coat hands in mineral oil.

Bearing storage: Bearings should be stored room temperature and a humidity level 60% or less.

Installation: Depending on bearing type and fitting conditions, bearing installation methods vary.

Preparations: Prepare a clean and dry work area. Completely remove any contaminants, chips, etc. from all the parts related to a shaft and housing prior to installing. The bearing mount should also be inspected to identify whether its dimensions, profile and roughness are within the respective specified tolerances of the bearing.

Press-fit installation: With the use of a press machine, the press-fit method is widely used for bearing installation. The bearing ring is press-fitted slowly using a backing strip for support.

Shrinkage fit: Another widely used method involves dipping the shaft in hot oil to expand its bore before pressing the inner ring to the shaft shoulder until cooled. The inner ring should not be heated to over 120°C.

Run test: This is essential to checking whether the bearing was installed correctly. The shaft or housing must first be rotated by hand, then run only at a low speed under no-load conditions by the power. If no errors are detected – signs of which would be a high metallic sound or irregular sound, or a rapid rise in bearing temperature – then the running speed can be increased gradually.

Washing: Any dismounted bearing should be washed by light oil or kerosene for complete removal of foreign matter, done in two steps – Rough washing removes oil and foreign matter, while finish washing is done for fine washing of the roughly-washed bearing. Rust preventive treatment must be applied to the washed bearing immediately after washing.

Take care of your bearings to expect a long running life from them, and a good return on investment for you.