Proper handling techniques are a necessity in order to maximize bearing life and performance. From shipping and receiving to unpacking, installing, disassembling and rebuilding, a bearing is exposed to a great deal of handling. Done incorrectly at any stage, this handling may reduce the life of the bearing.
But, fear not. By understanding and following proper techniques, you can reduce bearing damage and downtime, and see significant productivity gains.COMMON MISTAKES
The most common installation mistakes are improper bearing setting and adjustment. Set or adjusted incorrectly, the bearing is at risk for conditions such as misalignment, nicking or spalling, all of which may lead to premature failure.
A bearing is a hard-working machine component, but that doesn't mean it is indestructible.
Besides the initial installation, consult manuals provided by the original equipment manufacturer for proper techniques and procedures when rebuilding equipment. During a rebuild, the entire system must be properly cleaned and relubricated to ensure the system is free of any damaging debris or particles. If not cleaned properly, replacement bearings and components still may be at risk for damage because the contamination might remain in the system. When the system is properly cleaned, it's equally important to handle replacement bearings and components in a clean environment so dirt or contamination isn't transferred into the system during the rebuilding process.
Other common mistakes that can diminish bearing life include denting the cup during installation and not pressing the cup correctly. In addition to carefully handling the bearing itself, remember that the bearing is affected by its surrounding components such as lubricants and seals. Carefully inspecting these elements will help you improve the overall performance of the bearing system.PROPER SOLUTIONS
First, ensure that the work area is clean and free of debris. Clean out the machine or equipment with a clean rag and gloves. Remember, solvents sometimes can help to loosen any hardened grease, and air hoses can clean out air holes or castings. Although an excellent method to clean out a bearing, if using an air hose, be sure to use proper safety equipment and do not blow any debris into or onto the clean work area.
Lastly, before final installation, check the seals and use an application-appropriate lubricant to gain additional security and better system performance.HELPFUL TOOLS
Induction heaters: Induction heating is a superior, fast, clean and controlled heating method for bearings, gears and other products requiring a press fit. It is a safer and more environmentally friendly alternative to traditional heating methods such as oil baths or blow torches.
Heating the bearing with an induction heater increases the diameter of the bearing slightly to allow easy placement over a shaft. This tool eliminates any damage to (or debris from) the bearing when moving over the shaft. If you try to place an unheated bearing over the shaft, microscopic particles may break off and get into the machine, causing premature bearing and component damage. Once the bearing cools down, it grabs the outside diameter (OD) of the shaft, enabling it to have a proper fit so it doesn't move or spin in place.
Proper bearing maintenance and handling practices are critical. Failure to observe the following warnings could lead to a risk of serious bodily harm.
Never spin a bearing with compressed air. The rollers may be forcefully expelled with great velocity.
If a hammer and bar are used for bearing removal, fragments from the hammer, bar or the bearing can be released with high velocity. A mild steel bar is preferred since it is less susceptible to fragmenting.
When installing or removing bearings, always wear safety glasses or goggles.
Cleaning solvents may be toxic or flammable. Ensure adequate ventilation and wear protective clothing.
Remove oil or rust inhibitor from parts before heating to avoid a fire or fumes.
When using an induction heater, make sure the heater has an automatic demagnetizing feature. An extremely magnetic bearing may collect unwanted debris. Also, use a feeler gauge to ensure the backface of the bearing doesn't move away from the shaft's shoulder. And, do not overheat the bearing since this may damage, soften or misshape the bearing. Temperatures of 200 to 250 degrees Fahrenheit will generally allow it to overcome most fitting conditions.
Feeler gauges: It's difficult for the naked eye to see if the bearing is sitting against the shoulder. Therefore, use feeler gauges to measure thousandths of an inch between the surfaces. This ensures proper seating.
Dial indicators: Use these to check the end play (amount of shaft movement axially, relative to the housing) in tapered roller bearings. To make sure there is proper clearance (end play), follow this procedure: After mounting a dial indicator on the housing with the indicator point on the end of the shaft, move the shaft in one direction axially, while rotating or oscillating. Set the indicator to read "0". Move the shaft in the opposite direction, again while rotating or oscillating. The indicator will read the amount of end play in the system. Each application is unique, so consult your equipment manufacturer for the proper amount of end play for your application.
For spherical, cylindrical and ball bearings, clearance is measured in a radial direction and is affected by the class of bearing ordered and the fits. Check critical applications by feeler gages or dial indicators. It's important to follow the design engineers' requirements when installing all bearing types. Bearing manufacturers offer classroom and hands-on training in all of these methods, as well as on aspects of bearing maintenance.
Bearing or gear pullers: If planning to reuse a bearing or gear, pullers are a useful tool for removing them safely and properly. Compare the "reach" and "spread" of the puller with the product to be removed and select a puller with dimensions larger than those of the job. Make sure the jaws don't interfere with the free movement of the cage. A very common mistake is to attach the jaws to the cage and begin the pulling operation. For proper removal, the jaws must engage the bearing's backface.
When you properly handle bearings, you greatly minimize damage. This ultimately saves your company time and money.
This article was written by the Timken Company. To learn more about bearing handling techniques, training programs or tools to maximize bearing life, call 330-438-3000 or visit www.timken.com.