In operation, all rim and wheel assemblies are subjected to loads and forces which can lead to structural fatigue and cracking. If cracks are left undetected, a rim or wheel could suffer a catastrophic failure, with potential risk to the health and safety of persons in the vicinity.
Cracks are detected by careful inspection of the components. Where practicable, such an inspection should be performed by the original manufacturer of the rim or wheel assembly, or by their agent. Where this is not possible, the inspection should be performed by a competent person in accordance with the Australian Standard 4457.1. The Australian Standard stipulates rigorous and consistent controls for the inspection, maintenance and repair of wheel and rim assemblies on earth moving machinery. The following guidelines for proper inspection and testing are based on the Australian Standard.
In-service Visual Inspection
Wheel and rim assemblies should be visually inspected at regular intervals, and any flaws or damage must be marked for repair.
Testing should be carried out at intervals that take into account work-site conditions and usage. Prior to testing, all areas to be examined should be free of scale, dirt, grease or paint. Failure to remove these could interfere with observation and interpretation, and lead to inaccurate results. Service life should be recorded and test reports retained.
General Inspection Requirements
All components of rim and wheel assemblies must be inspected for mechanical damage. Additionally, each component of the rim should be tested using magnetic particle testing or ultrasonic testing.
Magnetic Particle Testing
Magnetic particle testing is a popular, low-cost method to perform nondestructive testing (NDT). It is applied to materials that can be magnetized or strongly attracted by a magnetic field. When ferromagnetic material (typically iron or steel) is defect-free, it transfers lines of magnetic flux (field) through the material without any interruption.
But when a crack or other discontinuity is present, the magnetic flux leaks out of the material. As it leaks, flux attracts ferromagnetic particles (iron powder), making the size and shape of the discontinuity easily visible.
Ultrasonic testing is an NDT method with superior depth penetration for flaw detection and sensitivity to both surface and subsurface discontinuities. An ultrasound transducer, connected to a diagnostic machine, is passed over the component being inspected. The transducer is typically separated from the test object by a couplant (such as oil). Sound energy is introduced and propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy is reflected back from the flaw.
1. Lock Ring Inspection
The lock ring should be visually inspected for wear, corrosion and deformation. If the ends of an unmounted one-piece lock ring are not touching, or overlapping, the lock ring should not be used.
2. Bead Seat Band Inspection
The bead seat band should be visually inspected for cracks, wear and corrosion in the areas in contact with the lock ring, flange, rim base or any weld.
Magnetic Particle Testing
The area of the bead seat band in direct contact with the flange, as well as any weld on the bead seat band, should be subjected to magnetic particle testing.
3. Flange Inspection
The area of the flange in contact with the bead seat band or the rim base, as well as any butt weld or other form of weld on the flange, should be visually inspected for wear, cracking, fretting, corrosion, deformation or damage.
4. Rim Base Inspection
The area of the rim base in contact with any flange, bead seat band or lock ring should be visually inspected for wear, cracking, fretting, corrosion or damage. The valve (spud) hole should be checked for corrosion, ovality and cracking. In addition, the area across the inside surface of the rim base should be visually inspected for corrosion. The mounting face of the rim base should be verified as suitable for fitment. For wheel assemblies, the disc should be examined for ovality in the holes, as well as cracking between the holes and at circumferential welds.
Magnetic Particle Testing
The following sections of the rim base should be subjected to magnetic particle testing:
- The area in contact with the flanges and the back section fillet radius.
- The area in contact with the lock ring and any O-ring groove.
- Any transverse weld.
- Any circumferential weld.
Where a weld defect is detected by magnetic particle testing, the extent of the damage should be determined through ultrasonic testing or grinding out.
5. Wheel Disc Inspection
The area around wheel disc welds should be visually inspected and subjected to magnetic particle testing. Mounting holes should be inspected for ovality and circumferential cracking. The mounting face of the wheel disc should be verified as suitable for fitment.
These are industry best practices that RIMEX has adopted worldwide for superior wheel and rim maintenance, along with reduced costs. To find out more about the RIMEXs Inspection and Repair program, click here.