Influence of SLS process parameters on cushion properties and sustainability of TPU lattice structures for automotive seating

Thermoplastic polyurethane lattice structures fabricated by selective laser sintering (SLS) are a promising alternative to conventional foams for cushion applications. However, the influence of SLS process parameters on automotive industry standard cushion properties, sag factor (SF) and hysteresis loss rate (HLR), remains uninvestigated. This study evaluates the effects of laser power, scan speed, and hatch distance on SF and HLR through cyclic compression testing using an L25 orthogonal array design, supported by microstructural characterisation and comprehensive predictive modelling spanning polynomial regression and machine learning approaches. Statistical analysis and microstructural evidence consistently identified laser power and hatch distance as the dominant governing factors, while scan speed exhibited negligible influence within the investigated range. HLR exhibited weak process sensitivity, suggesting energy dissipation is not readily tunable through process parameters alone. Multi-objective optimisation identified process parameters satisfying targeted cushion properties, and a full-scale automotive seat prototype was fabricated to demonstrate manufacturing feasibility. Comparative life cycle assessment revealed that the environmentally preferable manufacturing route depends critically on production volume and prioritised impact category, with SLS offering advantages at low production volumes. Collectively, the proposed framework provides systematic process knowledge for the rational adoption of SLS-fabricated TPU lattice cushions in automotive seating.