Quality Requirements for Laser Cutting of Titanium Sheets

Different titanium alloys are frequently used in the aerospace industry owing to attractive properties at high temperature service. Manufacturing of those parts is performed by different conventional and non-conventional methods, where laser cutting is one of the latter. Conventional cutting methods face difficulties for cutting these alloys due to their poor thermal conductivity, low elastic modulus, and high chemical affinity at elevated temperatures. High demands on quality and security within the aerospace industry result in high requirements on the part after cutting. To accommodate the requirements, it is necessary to process knowledge about how the laser cutting process affects the material in terms of surface finish, Heat Affected Zone (HAZ), mechanical properties, and microstructure. We have established an accurate method for evaluating titanium laser cut quality so that it may be referenced in the design phase or purchase order. This enables us to control our laser cutting quality.

The goal of this paper is to introduce industrially-applicable methods of titanium laser cut quality assessment using International Standard ISO 9013 and to introduce a reference guide for quality inspectors in the development of acceptance criteria, test sample instructions, sampling period, and qualification period. Statistical Design of Experiment (DOE) based on factorial analysis is introduced to identify the acceptance criteria. The laser cut quality factors are derived from Commercially Pure (CP) titanium (grade 3) sheets. Significant control factors have been found on eight important quality characteristics: surface finishing, cut edge roughness, cut edge squareness, kerf, burrs (dross) height, HAZ Hardness, HAZ microstructure and width.

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