Laser texturing of a multilayer DLC from nano-liquid-diamond precursors via microsecond laser pulses

Diamond Like Carbon (DLC) coatings have well known mechanical properties, including high hardness, chemical stability, optical transparency and biocompatibility. In addition they are frequently used in multilayer coating systems. Laser surface texturing of DLC coatings can be a tailoring solution to optimize the coating functional parameters like roughness, wettability, wear, corrosion resistance, etc. Furthermore, compared to mechanical grinding, local laser removal could be a suitable technology for repairing locally damaged coated parts (i.e. worn surfaces, corroded surfaces, etc.) In the present work, laser surface texturing and controlled laser removal of a multilayer DLC coating obained from nano-liquid-diamond precursors have been studied using a 8W Q-switched laser (λ=532 nm) with microsecond pulses. Textured ablation as well as full planar decoating are shown through proper adjustment of laser texturing parameters

The upgrade of the ASACUSA scintillating bar detector for antiproton annihilation measurements

Antiproton annihilations on matter nuclei are usually detected by tracking the charged pions emitted in the process. A detector made of plastic scintillating bars have been built and used in the ASACUSA experiment for the last 10 years. Ageing, movements and transports caused stress on the internal mechanical structure and impacted mostly on the optical readout system which was eventually upgraded: the so far used multi-anode photo-multiplier tubes (PMTs) have been replaced by silicon photomultipliers (SiPM) and the front-end electronics had to be adapted to cope with the new signal formation. This work describes the design and operations of the upgrade, as well as the validation tests with cosmic rays

Deep Drawing of AISI 304 Blanks with Polymer Punches Produced by Additive Manufacturing: Effects of Process Scalability

Rapid tooling is a methodology which aims to integrate additive manufacturing into the production of tools to be used in casting, forming or machining processes. In forming, rapid tooling is applied in the production of metallic or plastic tools that guarantee good performance in small- and medium-sized batch production. However, most punches tested to date have dimensions measured in millimeters and are therefore unsuitable for typical real-world industrial processes. In this study, the performance of plastic punches with geometries designed for industrial application was investigated. A deep drawing process involving AISI 304 blanks was created for the manufacturing of cups. Experimental and numerical analyses were conducted to measure the quality of the cups produced and the behaviour of the punches involved. The results indicate that when punch dimensions increase, a more precise cup geometry is produced (99% of drawing depth, 98% of cup precision on the fillet radius, and roundness error equal to 0.53%)

Poly(methyl methacrylate) Coating of Titanium Workpieces to Reduce Burrs in Micro-drilling

A technique to reduce burr height in titanium micro-drilling is presented: a poly (methyl methacrylate) coating was applied before machining on the upper and lower surfaces of a titanium specimen (0.5-mm thick). After drilling, a cleaning process (acetone bath) was executed to eliminate the coating, and holes with less burr were obtained. The coating process was executed with a spin-coating machine. To test the efficacy of the technique, two different coating thicknesses (7.9 and 5.4 μm) and two drill bits (0.25- and 0.5-mm diameter) were evaluated. Qualitative and quantitative analyses of the holes obtained were performed with scanning electron microscopy and three-dimensional microscopy, respectively. The results highlight the efficacy of the technique to reduce the burr height by 70% in coated titanium relative to that in an uncoated titanium sheet