Bearing Installation and Removal: Here Are the Basics
To achieve the full life of a product or appliance, it is important to ensure that roller bearing or radial ball is installed properly. If it is not mounted correctly, the impact will be a premature failure, reduced productivity, and could become a potential health hazard. This post explores the tips for installing non-housed bearings as opposed to the housed models.
It is prudent that all the safety concerns are addressed appropriately, ample time allocated, and the entire process understood before the task can commence. Besides, investing in the right tools, training, and time can help to cut associated costs and extend the lifespan of respective and machine. To put it more emphatically: “doing it right for the first time” is mandatory when working with machines. Remember to wear the right protective equipment.
Mechanical Bearing Removal and Installation
The first step is removing a bearing that failed. The best option for this is using puller and presses because they are safe, they minimize damage to the shaft & housing, and help to save time. One great tool for this task is the two-and-three jaw mechanical pullers that force the bearing safely out on the outer ring.
Another type of removal tool is the separator that is designed with two plates that are placed behind the bearing. If you are dealing with heavy-duty bearings, the separator can be designed with hydraulic-assist rams. Though the need to use this method is defined by size and space limitation, shaft gouges and nicks could require you to use metal removal.
NOTE: If you go for metal removal, important dimensional tolerances and correct fitting could change. It is prudent to avoid open flames or sparks if possible.
Once the bearing is removed, it is not advisable to reuse it. However, you should carefully examine it to determine the cause of failure. In some cases, the stress can cause damages that are impossible to see using the naked eye. Often, advanced analysis and experience to establish the cause of failure might be needed.
The only time that you can re-use a bearing is if it is resent back to the manufacturer. The designer will clean, inspect, measure, regrind, and give a go-ahead for reuse. However, this method is only cost-effective when dealing with big and expensive bearings.
When you acquire a new bearing, it is very important to handle it carefully. The best way to handle bearings is ensuring you have a clean, dry and vibration free storage. It is especially crucial to avoid unwrapping the bearing until it is ready for installation. Besides, you should not wipe or clean the factory lub unless the instruction requires you to do so. Here, cleanliness is the way to go.
Ensuring that exact bearing is utilized is very crucial. There are two main methods you can use to identify mechanical components: direct measurement and using the product number. If you are using a bearing from a reputable manufacturer, the bearings will always be marked with numbers that denote dimensions and tolerances. If you need to measure the item, make sure to use a vernier micrometer with a precision of up to 0.0001 inches.
Before installation commences, ensure that the housing and shaft are clean and without burrs. Though many industries prefer to use emery, it is important to appreciate that even particles generated by emery paper could still contaminate the bearing. It is advisable to consider using the industrial scotch-bright pads to clean the shaft and housing. Then, use light machine oil should be used to remove moisture. In addition to this, you must maintain cleanliness during the entire process.
Make sure to also measure the housing bore and shaft to ensure they fall within the recommended tolerances for the bearing and machine. Here, you should use tools such as slide caliper or micrometer.
The level of force that you should use to mount a bearing depends on the type and degree of fit. In many applications such as electric motor shafts, a press fit will be present if the ring is rotating. This implies that the inner ring will need a press-fit while the outer one will require a clearance-fit.
If the bearing is less than 50mm in diameter, consider using a bearing driver if its rings are installed using a light interference fit. Driving tools consist of a dead bloc hammer, polymer impact rings, and metallic tube. The tube driver is multipurpose and can be used with grease seals, oil seals, and bushings.
Ensure to use a safe press that is firmly fixed to a firm workbench. Besides, a rack and opinion should also be used together with a long handle for leverage. Pressing down the handle, apply pressure on the handle slowly supporting the machine using an anvil.
Thermal Removal, Installation, and Methods
When you raise or lower temperature of a bearing, housing, or shaft, the expanding and cooling of materials allows you to remove the bearings with ease. Note that the precautions used in the mechanical process also apply here. First, it is important to ensure that the housing and shaft are clean and free of burrs. Besides, you should ensure that measurements are done correctly to ensure that both the dimensions are within the recommended range. If you realize that the housing or shaft has dimensions that fall outside the recommended range, they need to be replaced.
Though bonding agents can be used to temporarily address the problem, it can only work for a short period. For example, liquid nitrogen can be used to lower the temperature of steel should be used when an extreme fit is noted. This is the reason why technicians place diameter shafts outside overnight and heat bearings in the morning before assemblage.
NOTE: Water that is released in the process can cause corrosion.
Other bearing heaters that you can use include the heated pizzas, cone type, and pizza oven. You can also use an oil bath. The common thing with these methods is that they are very slow and indeed, dirty. Instead, you should consider more advanced methods such as induction heaters that are safer, clean, faster, and more effective.
Induction heaters generate strong magnetic fields that induce eddy current on the metallic shaft. A secondary coil is connected to pass low alternating current while the bearings serve as short-circuits. The effect is that rings that are closer to the bar heat faster. The modern heaters have a method of clearing the byproduct using demagnetization.
It is important to appreciate that to use a temperature probe, it should be placed on the inner ring so that the resultant expansion can accommodate a press shaft and fit. The right temperature setting should be 230 degrees F or 110 degrees C.
When you decide to install a roller or radial bearing, it is prudent to ensure it is done properly following the right procedure and tools. Besides, you have to ensure that all safety procedures are followed. Remember that no matter what: “You have to get it right the first time".