A friction stir spot weld simulation procedure is necessary to predict weld quality and improve process parameters. Although lagging behind FSW, FSSW simulations were significantly extended for automotive and microwelding applications. Due to the process's microscale complexity, finer models than FSW/FSSW are required. This work presents an analytical technique with a thermal transient implicit FE model of pinless micro-FSSW to facilitate rapid parametric research and reverse engineering heat production. This simulation introduces a birth and death technique to represent the plunging process. Heat generation was calculated using the product of the torque (τ) and the tool rotational speed (ω) obtained from experimental research. Three models of analysis are introduced. When the temperature reached 330 to 350 °C, the material softens; Model 1 fails to sustain axial load due to material softening above 330 °C. Sliding Sticking Model (Model 2) performed well when the logistic equation approximated the suggested δ and µ per temperature. In this concept, the heat produced by plastic deformation can offset the power loss from friction heating. Compared to the temperature readings in the center of the weld, the temperature difference for Models 2 and the Model 3 was more widely accepted than for Model 1. © ASM International 2026.