20 06 19

Pagina 1

Course of ADVANCED MANUFACTURING PROCESSES Proff. Michele Monno – Barbara Previtali – Matteo Strano SURNAME NAME PERSONAL ID Exam - June 20th 2019 Exercise n. 1 – Scientific article comprehension Your company is interested in a new technology in order to produce advanced high-performance coatings. Particularly, your company is interested in coatings characterized by high heat, high wear strength and corrosion resistant. In this perspective you have at your disposal powder of Co-Cr-Mo alloy with a mean range particle size of 45-125 µm. In order to perform your explorative experiments, you also have, a Nd:YAG laser source, which characteristics are reported in Table 1 and a substrate of g-TiAl. Considering your explorative investigation, the paper “Nd:YAG laser cladding of Co-Cr-Mo alloy on g-TiAl substrate”, by M. Barekat et al, 2016, may be helpful for determining the production parameters to obtain a good clad performance. 1. Considering the same condition reported in the article, it is asked to determine the collimated diameter (Dc) and the correct optical set-up in terms of focusing lens (ffoc), considering three option: § ffoc=250 mm; § ffoc=300 mm; § ffoc=350 mm; In order to solve this request, you must consider a correct use of focusing lens; its diameter should be covered for the 80%. Table 1 Meaningful data Symbol Value Unit Laser machine Laser source - Nd:YAG - Laser average power Pavg 700 W Beam quality factor M2 39 - Focusing lens diameters Dl 20 mm Process Parameters Material substrate - g-TiAl - Powder material Co-Cr-Mo alloy - Process Needs External diameter of the crown Dest 40 mm Internal diameter of the crown Dint 28 mm Waist diameter, d0 [mm] Dc [mm] ffoc [mm] 2. Considering Figure 1, it is asked the determination of the powder velocity (vparticle).…