Initiation mechanism for galling

Galling investigations during hot forming

Published: 5 December 2011

In hot forming, different tribological problems arise when the tool and work-piece interact during the forming process at elevated temperatures. Wear and surface damage of forming tools can be detrimental to the quality of the final product and these can also have an adverse impact on the process economy due to frequent maintenance or replacement of tools.

This project focuses on investigating the impact of wear mechanisms such as galling, during the metal forming operation. The literature review carried out revealed that the awareness of tribology and its application in metal forming processes (at high temperature), has increased in the recent years. A considerable amount of work has been done to enhance the understanding of the response of different materials and parameters involved and also to improve the process itself. However, despite these developments, there exist major gaps in knowledge pertaining to the occurrence of friction and wear in hot sheet metal forming.

Extensive experimental studies have thus been undertaken to bridge some of the knowledge gaps related to tool wear and failure mechanisms in the hot stamping process. These studies have involved both the systematic analysis of actual worn tools as well as parametric tribological investigations in the laboratory.

The main damage mechanisms during hot sheet metal forming were identified. Mechanical fatigue induced by high friction as well as galling were found to be the most severe damage mechanisms on forming tools. A mechanism for the initiation of galling has been proposed and different techniques for alleviating the galling problem are investigated.