FAQ of THB Bearings Co., Ltd.

Have a question related to bearings? THB has your answer! View our bearings FAQ today, or call to lear more!

Q1. Are THB's Rolling Element Bearings RoHS Compliant?
RoHS stands for the Restriction of Hazardous Substances directive adopted by the European Union (EU) and took effect in July 2006). RoHS is often referred to as the "lead-free directive," but it restricts the use of the following six substances:
Lead (Pb)
Mercury (Hg)
Cadmium (Cd)
Hexavalent chromium (Cr6+)
Polybrominated biphenyls (PBB)
Polybrominated diphenyl ether (PBDE)
THB's rolling element bearings can be conformed to RoHS compliant.

Q2. I have a high temperature application, can I use stanard lubricants?
Most standard Lithium-based solutions are not designed for high temperatures. Most standard grease will operate consistently at a maximum temperature f 80°C and can withstand brief periods at 110°C. If your application goes higher than this then you need a more specialised lubricant. If your application goes beyond 350°C then you may need to consider solid lubricants or ceramic bearing materials(or a combination). We recommend you to contact THB for impartial advice.

Q3. Can I work out how much axial clearance I have in my bearing?
Most bearing manufacturers never give this information in their catalogues. It is suprisingly inexact and does not fall into any international standards. As a very rough rule of thumb it is eight to ten times that of the radial clearance. We would strongly recommend that the advice of the bearing manufacturer be taken on this as other factors such as heat expansion either locally or ambient, load conditions, rolling element type etc will all play a role in the axial movement.

Q4. What are ABEC ratings?

Q5. What's the difference between bearing seals and shields?
Seals and shields are both in place to keep contaminants out of a bearing. In order of effectiveness, the enclosures that are offered are as follows: metal shields, rubber non-contact seals, Teflon non-contact seals, and rubber contact seals. Not surprisingly, as the sealing performance is increased, the torque required to turn the bearing will also increase due to the increased friction caused by the seal/shield. The application's condition and life requirements are important to know to determine the best shield or seal choice.

Consult with one of THB' s sales or engineering personnel to help determine what is best for your particular application.

Q6. Should I use grease or oil in my application?
Grease is typically used at lower speeds and with less torque-sensitive applications. Oil is typically better when low torque or high rotational speeds are an important consideration.

Q7. When should I use spherical bearings?
Spherical bearings are self-aligning and can carry high loads and tolerate shock loads. These bearings can accommodate a misaligned shaft and are suitable for applications involving swivel movements, high alternating loads, very high radial loads with a unilateral load direction and high shock loads.
Typical spherical bearing applications include vibrators, shakers, conveyors, speed reducers, transmissions, and other heavy machinery.

Q8. The bearings in my application only briefly experience high temperatures. Can I switch to a standard lubricant instead of the high temperature lubricant used by the OEM?
Most standard lithium-based lubricants will operate a continuous maximum temperature of 80°C, and can withstand brief periods at 110°C. I suggest you measure the operating temperature at the bearing.
It is important to look at operating and maintenance costs. The labor cost to replace a failed bearing even a single time will more than offset any potential cost savings from using a standard lubricant instead of a high temperature lubricant.

Q9. What causes bearing noise?
Bearing noise is a function of both the bearing and the way it is used. Bearing noise is not generally influenced by ABEC and there is no fixed standard among bearing manufacturers for acoustic noise. Some external factors which affect bearing noise include, lubricant type, excessive bearing load, and improper installation.

Q10. What factors increase or decrease bearing torque?
Factors that increase bearing torque include:
Increased number of balls in the bearing
Tight crimp ribbon retainer
Tight radial play
High lubricant viscosity
High lube fill in the bearing
High applied bearing load
Factors that decrease bearing torque include:
Fewer balls in the bearing
Crown type or loose crimp retainer
Loose radial play
Low lubricant viscosity
Low lube fill in the bearing
Low applied bearing load

Q11. What is Preload?
Preload is a side load that is applied to a radial ball bearing that takes the extra play between the balls and raceway out of the bearing. The side load is normally applied by a spring, so that the system can expand and contract as the conditions fluctuate. Designing a preload system into a bearing application will ensure the quietest possible operation with the longest life.