FEATURE SEALS & BEARINGS
CORRECT BEARING INSTALLATION maximises operating life in critical applications
The repercussions of a poorly mounted bearing can be catastrophic and using the correct tools is critical to safety and reliability, says Martin Wakelin of Carter Manufacturing
T
he correct installation of bearings can save time and dramatically increase
the life of bearings as well as maximising the availability of critical plant and machinery by avoiding costly breakdowns. The key here is to ensure that the appropriate tools for the mounting of the bearings are on hand for the engineer at the installation/assembly stage. Using the correct tools ensures that
bearings are mounted easily and quickly without causing damage to the bearings or surrounding equipment and in a safe and reliable way. The more critical the application the
more important it is to ensure the bearings are fitted correctly first time, every time. V-grooved bearings, for example, are widely used in aerospace and motorsport applications; on aircraft airframes in critical areas such as actuator flaps and landing gear; and in motorsport applications they are used in suspension systems and struts. By using the most appropriate installation tools the bearing can be better seated in the housing, will perform its function better and is far less likely to be damaged. The roll stake tri-roller tool has provided
an even, smooth and mirror-like surface to the swaging lip on the bearing. Virtually no gap is visible between the two components. This is in stark contrast to the solution provided by the anvil tool where the surface is not as smooth as the tri-roller tool and an obvious gap between the swaged lip and the housing would suggest an inferior retention and mating between bearing and housing. Using more basic tools can result in issues such as abrading, sheared edges, gauges and micro-cracks. These primarily arise because the forces used for anvil staking tools and the magnitude of material stress are much greater when compared to tri-roller swaging tools which stress the material much less by causing the material to deform in small increments rather than forcing a large change in one movement. The collective result of these factors is that by using a roll stake tri-roller swaging tool the bearing is better seated in the housing, better able to perform its function and less likely to be damaged. A number of different bearing swaging,
28 SPRING 2017 | IRISH MANUFACTURING
from the bearing’s outer ring v-groove against the housing in order to locate it precisely and securely. Roll stake or Tri- roller tools are typically available in either Drill-Press or portable style. Both types are normally supplied with both primary and secondary swage locating anvils.
cutting and installation/removal tools are available as well as proof-loading and breakaway torque testing tools for the correct installation, testing and removal of grooved or plain spherical bearings, sleeves and housings. These can be used to complete operations such as bearing swaging and spinning; roller swaging; bearing, ball, anvil, chisel and V-groove staking; proof-loading; and load testing. If a particular tool is not available from stock some suppliers can provide custom- engineered bearing tools on rapid delivery for specific installation tasks.
TRI-ROLLER SWAGING TOOLS Tri-roller or roll stake swaging tools have been developed as an improvement to the traditional methods of Anvil or two-wheel swaging. These offer the advantage of allowing the three rolling elements in the tool to better contact the V-groove surface of the bearing at the correct angle, allowing the V-groove to fold over into the housing. Traditional two-roller and Anvil tools can cause damage to the V-groove lip. The Tri-roller tool uses a combination of downward pressure and roller rotation. The rollers push material
Portable swaging tool
CUTTER TOOLS Accurate removal of a bearing from its housing is as important as correct installation. Cutter tools are specifically tailored to each bearing size in order to remove only the bearing itself with minimal or no damage to the housing. V-groove bearing cutting tools, for
example, should be designed to work by cutting down into the swaged V-groove of the bearing. This cut into the V-groove of the bearing weakens the bearing lip that was swaged against the housing so that it collapses easily into the bore when the bearing is pressed out. The cutting tools should be designed in
such a way that the cutter only cuts the bearing and therefore preserves the integrity of the housing. Typically available as portable style or drill-press tools.
Portable breakaway torque test tool
INSTALLATION & REMOVAL TOOLS Installation and removal tools are designed to insert and position a bearing accurately prior to swaging and to carefully remove the bearing once the swaged lip has been removed. The tool keeps the bearing perpendicular to the housing to ensure that the housing is not damaged during installation or removal. If bearings are just pressed into the housing the sharp edges of the bearing could score the housing bore. If the housing fits are designed to be
loose an installation tool will not be needed. However, generally, removing a bearing will always require a tool as the swaged lip will exert a good pressure against the housing even if it has been cut. Cutter tools are designed to allow the V-groove lip to collapse but the bearing still needs a force applied to it so that the bearing breaks free.
TEST TOOLS
Testing such as proof load and breakaway torque testing are normally required as part of bearing replacement certification
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