Polymer extrusion processes in tire manufacturing: a systematic review and bibliometric analysis

Tire extrusion is a thermo-mechanical process in advanced tire manufacturing in which compound rheology, die/tooling design, and operating history jointly govern dimensional accuracy, stability, scrap, and downstream performance. This study provides a systematic review and bibliometric analysis of tire-extrusion research published between 2000 and early 2025 using an integrated Scopus–Web of Science corpus enriched with OpenAlex, CrossRef, and OpenCitations, complemented by automated keyword completion (YAKE) and cited-reference completion. We map production and collaboration patterns and reveal conceptual and intellectual structures using co-word/thematic analysis, thematic evolution, co-citation networks, and Reference Publication Year Spectroscopy (RPYS). To mitigate terminology-driven topic drift and enable engineering-centred interpretation, we introduce a technology-depth sensitivity (scope-control) layer that separates a broad tire-related corpus from nested, technology-explicit extrusion cores and organizes evidence through non-exclusive tagging by engineering degrees of freedom (rheology/constitutive behaviour; tooling/flow/die engineering; extrusion hardware/process window; simulation/CAE; monitoring/control). Results show that the broad corpus is dominated by materials/circular-economy themes, whereas the technology-explicit cores reveal a distinct process-engineering and CAE stream centred on die design, flow balancing, constitutive modelling, and simulation-supported optimisation. Finally, we translate these findings into actionable industrial levers and KPI-level implications for tire-profile extrusion/co-extrusion, including gauge stability, interface integrity, thermal hotspots/scorch risk, and reduced die-qualification time.