Laser turning of PMMA with ultrashort laser pulses using UV and IR

Abstract

Tangential laser ablation as carried out in the ultrashort pulse laser turning process is an approach to generate rotationally symmetric workpieces of high precision on a microscopic scale. The lateral laser impingement on the cylindrical workpiece ensures both process stability and control, while the use of ultrashort pulsed lasers greatly reduces machining forces and heat input into the material.The flexibility in design makes this process a cost-efficient solution for prototype manufacturing as well as volume production and the feasible dimensions of the ultrashort pulsed laser ablation surpasses the capabilities of conventional injection molding. Due to its wide variety of applications in the automotive industry, medical technologies, healthcare supplies or in the lighting technology and optics, the machining of polymethyl methacrylate (PMMA) with focused ultrashort laser pulses represents an auspicious research subject.Against this background, we report on laser turning of polymer PMMA using ultrashort laser pulses for generating rotationally symmetric workpieces. By comparing two different wavelengths for the process, namely 1030 nm and 343 nm, the difference in ablation rate as well as the suitability for geometry generation is evaluated. Particularly, the effect of the Rayleigh range for generating steep and large muff shaped features and the laser spot formation on the cylindrical surface is being discussed. Supplementary, the pulse to pulse overlap and its effects on the process result on a curved surface is subject to the presented studies.