Large-size workpiece machining 1 Milling (machining) 1 Milling vibrations 1 Modal analysis 1 Salp swarm algorithm 1 Salp swarms 1 Stiffness 1 Stiffness adjustments 1 Stiffness coefficients 1 Swarm algorithms 1 Vibration level 1 Vibration reductions 1 Workpiece 1 large-size workpiece machining 1 milling vibrations 1 salp swarm algorithm 1 stiffness adjustment