How to Install Bearings

To begin, the bearing must be inserted into the housing. The installation process can lead to damage to the housing if this is not properly aligned.

In general, to do this correctly as part of a two-stage process, the tool should be used to gradually drift the bearing into the right position. The primary stage sets bearing position and concentricity, whilst this second stage helps guarantee an accurate centring of the bearing within the housing.

Some circumstances call for the use of a sleeve. In these applications, a similar process is used before the bearing is installed.

To ensure that a bearing has been successfully installed and poses no risk of being dislodged from the housing when presented with an axial force, tangible data-driven proof by the manufacturer is required. The proof load test can determine if the swage is safe and appropriately installed by applying a designated axial force on both sides of a bearing and measuring its linear displacement relative to the housing. Whilst approval criteria are generally defined on the process specification, we can advise whatever criteria thanks to our extensive industry knowledge.

The two most popular methods of proof load testing are anvil style on a hydraulic press, and portable style. Portable style is preferred for customers as it is compact, repeatable, quick to set up, and easily adaptable. The bearing is measured by a calibrated load cell connected to a digital load reader, using a threaded nut and wrench for force application. Bearing displacement is monitored by a DTI gauge in contact with a spring-loaded piston moving along with the bearing. The image to the left demonstrates this.

There is a wide range of methods of bearing swaging including anvil, ball, and segment staking, as well as two-wheel, tri-roller, and reverse swaging. It is generally recognised that tri-roller swaging is the best method of these options, and as such will be the focus of this section. For more information on other methods, please refer to our production portfolio which demonstrates instances of using alternative methods.

Tri-roller swaging can be done with either a drill-press style tool or a portable handheld tool. Whilst the use of either tool carries its own advantages, the general concept remains the same; a series of 3 angled rollers rotate within the bearing v-groove, gradually extending the bearing lip into the housing chamfer. To safely secure the bearing within the housing, this is done on both sides over the course of the two stages.

To ensure the continued centring of the bearing within the housing, the primary swage uses the primary anvil as a locating feature. The secondary stage is then carried out using a secondary anvil to contact the bearing v-groove on the opposite side of the bearing and maintain its original centred position.

This geometry of the tool is strictly controlled by either the manufacturer’s (e.g. Boeing or Airbus) or the US government’s specification. Improper compliance with this can result in failing an inspection, being recognised as non-conformance when audited by a customer, and premature failure.

To check a bearing has been properly installed beyond just look and feel, there are three common tests: proof load test, breakaway torque test, and swivel test.

The breakaway torque test, also known as the rotational torque test, determines the torque required to initiate ball rotation as shown in the image. As this has a direct impact on the mechanical system and can be negatively impacted by improper tooling, the torque is closely monitored.

To test this, a tool is inserted through the bearing bore to cause an interference fit. Torque is then accurately measured with an electronic torque reader. Caution should be taken during the test to prevent damage to the bearing, which could be caused if your tool allows for the over-compression of the ball from use with a threaded bolt and nut assembly

Swivel or tilt movement/misalignment torque can be defined by the torque needed to initiate movement perpendicular to the axis of rotation. This is a standard test for many Airbus specifications and is becoming more common with other big manufactures as well as in the motorsport industry. Ask UNASIS about our custom swivel torque tool today.

A cutting tool is necessary in the event of a bearing failing visual inspection, or for component repair.

The UNASIS cutting tool creates a crease on the lip of a bearing by precisely cutting a portion of the bearing v-groove. This allows the v-groove to fold into itself when extracted from the housing with an install remove tool, eliminating the possibility of housing damage and ensuring the housing component remains flight-worthy.

The process of bearing installation can be incredibly daunting as improper methods and techniques can damage expensive and hard-to-source bearings and housings. The best option to reducing these risks is having tools specifically designed to optimise repeatability whilst minimising time and costs. We are a supplier with decades of experience and knowledge in the application of bearings to assist you with any potential projects. To learn more about our stock of standard or custom engineering tools as well as our on-call design support, contact our team today.