Abstract: A brief evaluating method for transmission gear undercutting is proposed. The method is based on the technology of polynomial mutation operator and particle swarm optimization (PMOPSO). The undercutting model is established based on the parametric equations for involute gear profiles and the relationship between model solutions and undercutting points is investigated. The as-proposed method is used for evaluating undercutting of key gears in a power turret. The effects of modules and modification coefficients on undercutting are studied. The results imply that the proposed method is able to calculate gear undercutting rapidly. Meanwhile， the accuracy is geared to design requirements flexibly. The situation of key gear undercutting can be analyzed accurately by the proposed way， which may contribute to improve the transmission performance of turrets.

Key words: undercutting, polynomial mutation operator, particle swarm optimization, power tool turret, gear modification