Meaning
Cumulative thermal records compile the temperature profiles that a polymer melt experiences during extrusion or injection moulding. Manufacturers track melt temperature history to evaluate how many times a material was heated beyond its softening point because successive heating cycles degrade polymer chains. This parameter does not cover room-temperature storage periods but governs every phase from initial compounding through final forming.
Thermal Accumulation
Chain scission begins when polymers remain at elevated temperatures for extended durations. This degradation pathway reduces the molecular weight of the plastic and compromises the physical strength of the finished component. Extrusion operations in Chinese factories must document these heating profiles to comply with raw material standards.
Molders typically measure melt temperature history during the primary moulding phase.
Processing Influence
Fluidity under shear stress varies depending on how many times the polymer has been melted. Elevated temperature cycles increase the melt flow rate of the material, which can cause flashing or incomplete mold filling. Industrial audits in municipal development zones track these thermal variances to verify process stability.
Corrective actions require operators to adjust heater band settings or reduce dwell times in the barrel.
Defect Prevention
Polymer degradation produces volatile compounds that can cause surface blemishes or yellowing. Processing lines require real-time temperature tracking to prevent these cosmetic and structural failures. Mechanical testing verifies that tensile properties remain within specified engineering tolerances.
