Friction stir welding (FSW) is a versatile technique for fabricating polymer-polymer, polymer-metal, sim-ilar and dissimilar metals/alloys joints. Over the years, optimization studies have enabled the fabrication of high-quality weldments using this technique. However, experience shows that repeatability/repro-ducibility may not be attainable due to process disturbances, thereby necessitating wide tolerances in the strength of the ensued joints. This paper briefly highlights process inconsistencies documented in FSW literature and experimentally demonstrates the potential cause of such issues. Afterwards, a strat-egy for in-situ monitoring of process reliability in FSW is proposed. Being the first to investigate reliability issues in FSW, this research has three potential impacts on the FSW process. First, it highlights issues that should be of concern when using FSW for mass production jobs. Second, the proposed strategy could aid the implementation of a reliability-centred maintenance strategy. Third, it could form crucial technical considerations for implementing smart manufacturing in FSW.Copyright (c) 2022 Elsevier Ltd. All rights reserved.Selection and peer-review under responsibility of the scientific committee of the Symposium on Failure and Preventive Maintenance of Machineries 2022.