Material selection for off-highway heavy duty engine bearing applications is becoming more complex as there is a growing requirement to replace the traditionally utilized copper-lead based lining alloys due to adverse health and environmental concerns surrounding heavy metals. Although upcoming legislation is increasing the drive to find alternative lead-free solutions these have not been well adopted for all applications as there are limited products available that are matched to the excellent performance of leaded materials in tolerance to debris, ability to conform and prevention of seizure events.
This paper details the development of a new lead-free bronze alloy with a focus on improvements in conformability and seizure resistance compared to current lead-free materials. A new alloy composition is introduced which contains bismuth soft phase with optimized tin content which when combined with a lead-free electroplated overlay presents a robust material for applications where seizure performance might be a concern.
The present development provides a suitable product that will enable the future-proofing of off-highway heavy duty applications and offers a solution to inevitable future restrictions surrounding leaded materials. Results from bespoke rig testing and engine testing are detailed that support the material development.