Laser Cutting of Stainless Steel Thin Sheets with Pulsed Nd:Yag Laser

The parameters of laser cutting mainly depend on material and from thickness. In case of a given material and thickness many settings can be chosen. In this article we examine the laser cutting of 0,4 mm thickness stainless steel sheets with pulsed Nd:YAG laser. We examine the effect of cutting speed on cut quality in case of three different combinations of pulse energy and pulse frequency. Good cut quality and relatively high cutting speed can be achieved with 800 Hz and 20.7 mJ setting, we can cut higher speed, but poor cut quality with 400 Hz and 49 mJ setting

Laser beam cutting and welding of coronary stents

Coronary stents are thin-walled and mesh-structured metallic implants, which are made generally by laser beam cutting of high-precision tubes of 90-120 micrometer thickness. The tube material can be 316L stainless steel or L605 type cobalt-chromium alloy. The paper present how laser settings influence geometry and surface quality of the kerf and residual stresses, which play very important role in the precision of stent strut homogeneity. Hungarian Tentaur stent was developed 15 years ago. This coil stent made of 145 micrometers thick stainless steel wire contains 9-25 joints produced by electric resistance projection welding. Developments were bringing out for increasing flexibility of Tentaur stent, and a new design and a new tech-nology was elaborated, which’s based on laser beam mi-crowelding. TentaFlex stent also is constructed from austenitic stainless steel wire, but it does not contain any wire-crossing joint, because stent struts are configured from sinusoidal helix. Stent contains only two welded joints at its ends. Laser welding experiences of these joints are presented in the paper. A Trumpf PowerWeld Nd:YAG laser work station was used for welding, and after optimization of laser settings joints can’t produces from only one side of the coiled stent

A fókuszhelyzet szerepe erősen reflektáló anyag egyimpulzusos, lézersugaras fúrásakor

A megmunkáló lézer hullámhosszán erősen reflektáló anyagok megmunkálásakor tekintetbe kell venni, hogy az energia csak kis része hasznosul, a többi visszaverődik. Jelen esetben az 1070 nm-es hullámhos�- szon a réz és az ezüst számít ilyen anyagnak. A nyomtatott áramköri lemezek fúrásakor a rézréteget is át kell fúrni. Sokszor előnyös, hogy az erősen reflektáló anyagba kisebb furatokat lehet készíteni éppen a rossz energiahasznosítás miatt. Természetesen az egyimpulzusos, lézersugaras fúráskor a fókuszpozíciónak is nagy szerepe van: a fókuszált lézernyaláb fókuszában lehet a legkisebb, tőle távolodva nagyobb átmérőjű furatokat készíteni

Role of the Features of Focused Laser Beam at Pulsed Laser Cutting

In this article investigation of the roles of two important factors of focused laser beam, the focal spot diameter and the Rayleigh length as determining variables of the beam quality were made. The equations of these two factors are based on those most commonly used in the literature. The exchange between three different beam quality numbers were shown. It is proven on the basis of the scientific literature, that the beam quality degrades compared to the original data given by the factory of laser. The causes of the beam quality degradation are lens aberrations in the optical path of the given laser, and the shifting of the beam propagation ratio (M2) to higher values. A new equation for estimation of the new, lowest value for M2 factor is presented, based on the comparison of the laser cut material thickness to the depth of focus, which is two times the Rayleigh length