Temperature Control of Resin Vats and Feed Systems: Viscosity, Kinetics, Gradients and Process Capability

Temperature is a process state, not a secondary environmental note, in vat photopolymerisation. It changes viscosity, refill time, species mobility, photopolymerisation kinetics, dark reactions, volatilisation, optical response and the mechanical condition of the machine. A nominal vat setpoint does not establish the temperature of the exposure region, the incoming feed, the return line or the resin adjacent to a recently cured layer. This review defines a qualification framework for resin-vat and feed-system temperature control. It separates setpoint, sensor reading, local resin temperature and thermal history; maps spatial gradients and transient recovery; couples temperature to rheology, working curves and build duration; and requires independent alarms for over-temperature, unintended polymerisation and material loss. Heating is qualified with the actual vat, fill volume, circulation, cover, platform motion and exposure duty. No universal printing temperature, warm-up time, viscosity target or control-band width is supported. The deliverable is a bounded thermal process window for a declared resin, machine, geometry and maximum build time.