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The aim of this paper was to characterize different classes of materials, light metals, steels, cobalt-chromium-based and ceramic materials under tribological stress and to determine the reproducibility of the measurement results by monitoring the production, processing and analysis of the test materials. The results were used to ensure pre-selection of materials for use in the dry forming process. To depict real conditions at the edges of a forming process surface pressures of 10-200 N/mm need to be adjusted. For this purpose, the friction and wear properties were determined in a dry ball-on-disc test. The functional surfaces were produced by laser-cladding, selective laser melting, chemical vapor deposition (CVD) and laser hardening. The tested and selected classes of materials were steel (42CrMo, X110CrMoVAl 8-2), light metals (aluminum 6082, C95300 aluminum-bronze), cobalt-chromium alloys (Stellite 12, Stellite 21), ceramic (SN) and polycrystalline CVD diamond. The test setup of the dry ball-on-disc test included 10 N contact force, 10 mm traversing distance, 10 mm/s average speed, 40 % humidity and 24 °C ambient temperature. The resulting wear map includes five orders of magnitude of different wear rates and one order of magnitude of different coefficient of friction. An eligibility number is introduced for a better differentiation of the combined properties of the tribosystem of a tool material. [ABSTRACT FROM AUTHOR]

Macro effects can probably not be simply transferred to the micro range proportionally to sheet thickness because of possible influences of size and scaling effects. In order to investigate distortion effects in the micro range reproducible experimental conditions have to be realized. The capability of a developed welding set-up to maintain those conditions is shown. The set-up consists of a laser scanning head, a novel clamping device and deformation measuring systems. Due to low stiffness of thin metal foils, handling the specimen can influence its shape and properties significantly. Therefore, influences on the welding process are minimized by appropriate sample preparation, handling, and the use of an integrated non-contact deflectometry measuring system. The suitability of the set-up for deep penetration laser micro welding and investigation of distortion behaviour in the micro range is demonstrated. Influences of geometrical and process parameters on out-of-plane and in-plane distortion effects are reported. [ABSTRACT FROM AUTHOR]

Abstract: A one stroke micro blanking and deep drawing process is used to produce micro cups in a high quantity (200 strokes per minute) with an outer diameter of 1mm. For cutting and deep drawing one single hollow punch is used. The outer diameter punches the circular blank while the inner diameter serves as drawing ring. Investigations regarding the tool life show that the punching edge wears out quicker than the rest of the tool. Furthermore it is shown that the positioning of the tool has a high influence on the wear behaviour. [Copyright &y& Elsevier]

Laser application in sheet metal bending represents a flexible forming method, which does not require specialized mechanical tools or large external forces. Whereas the required process parameters leading to simple bending geometries can be estimated to some extent by analytical models, for complex structures it is mostly not possible. A sufficient planning flexibility is generally provided by numerical simulation, yet particularly time-consuming if applied to incremental processes. To optimize this, an extended understanding of the material response during laser beam bending is required. Based on in situ strain and temperature measurements an analysis of incremental stress behavior is undertaken at multiple positions on the laser averted surface. For transient temperature recording a thermal camera is used. The surface strains are continuously detected by an ARAMIS-system. To calculate stress values an approach is proposed, which adapts Hook's law on stress and strain for two-dimensions and which is further enhanced by plastic strain state and temperature changes. An analysis is provided for stainless steel (1.4301) and pure aluminum (EN AW-1050A), as well as for two cooling time periods in-between cycles. The incremental behavior of localized transversal stresses proves to be particularly complex. In contrast, longitudinal stresses approach a recurring incremental behavior pattern after very few initial laser scans. Furthermore, an indication on a material specific evolution of the plastic zone geometry is won. [ABSTRACT FROM AUTHOR]