Zlatko Kampuš

Bio: Zlatko Kampuš is an academic researcher from University of Ljubljana. The author has contributed to research in topics: Injection moulding & Finite element method. The author has an hindex of 9, co-authored 15 publications receiving 298 citations.

A novel method to test the thinning limits of sheet metals in negative incremental forming

Abstract: Single Point Incremental Forming (SPIF) is an emerging sheet-metal-forming technology, capable of manufacturing complex parts at low cost for small to medium-batch production. The present paper is focused on presenting an innovative and viable method to test the thinning limits of sheet metals in Negative Incremental Forming along with verification of the Cosine's law of thickness distribution. The Cosine's law was verified by comparing the experimentally measured thicknesses of incrementally formed parts with those predicted by the law. To test the thinning limit of a sheet metal, the idea is based on the forming of an axi-symmetric part varying its slope with depth corresponding to varying thinning. An arc of a circle was selected as generatrix to model such an axi-symmetric part. Based on the Cosine's law, mathematical expressions were derived to predict the thickness distribution along the depth of the part and the thinning limit of the sheet-metal. The Aluminum sheet metal was used as an experimental material. In order to test its thinning limit, the axi-symmetric part, modeled with a generatrix arc, was formed incrementally until it cracked. Thickness of the fractured part was measured at various points along its depth and compared with that predicted by the Cosine's law. The maximum thinning at a point, at which thickness followed the Cosine's law, was called the thinning limit of the sheet metal. In order to obtain accurate results, four such parts having the same generatrix design were formed. Based on these results, several axi-symmetric and asymmetric parts were formed at fixed slopes. It was found that the thinning limits obtained from the parts formed at fixed slopes were a little lower than those obtained from the parts modeled with the same generatrix design. As conclusion, a strategy to test the lowest possible thinning limits of sheet metals has been proposed. The proposed method is capable to test the thinning limits of sheet metals at reduced processing time and cost.

Genetic algorithms in materials design and processing

Abstract: Genetic algorithms (GAs) are biologically inspired computing techniques, which tend to mimic the basic Darwinian concepts of natural selection. They are highly robust and efficient for most engineering optimising studies. Although a late entrant in the materials arena, GAs based studies are increasingly making their presence felt in many different aspects of this discipline. In recent times, GAs have been successfully used in numerous problems in the areas of atomistic material design, alloy design, polymer processing, powder compaction and sintering, ferrous production metallurgy, continuous casting, metal rolling, metal cutting, welding, and so on. The present review attempts to present the state of the art in this area. It includes three broad sections given as: fundamentals of genetic algorithms, genetic algorithms in materials design, and genetic algorithms in materials processing. The first section provides the reader with the basic concepts and the intricacies associated with this novel tec...

Electric hot incremental forming: A novel technique

Abstract: In the current work, a new method is proposed for hot incremental forming. The method is based on simple tooling and is easy to employ. It makes use of electric current for heating hard-to-form sheet metals at the tool–sheet interface in order to fully utilize the formability of these materials. The potential effect of processing parameters, namely current, tool size, feed rate and step size, on the formability are investigated using AZ31 magnesium. In addition to this, the shape distortion of TiAl2Mn1.5 titanium workpiece after hot forming has also been addressed herein. Experimental results demonstrate that this technique is feasible and easy to control.

Electric hot incremental forming of Ti-6Al-4V titanium sheet

Abstract: Electric hot incremental forming of metal sheet is a new technique that is feasible and easy to control to form hard-to-form sheet metals. In the present study, Ti-6Al-4V titanium sheet was studied because it was wildly used in the aeronautics and astronautics industries. Although Ti-6Al-4V titanium can be well-formed in high temperature, the surface quality is a problem. In order to enhance the surface quality, it is very important to select the proper lubricant. At the same time, because Ti-6Al-4V titanium has a lively chemical property, it is very important to choose a processing temperature range in order to acquire excellent plastic property and to prevent oxidation. Various lubricants were selected in processing to compare the effect, and some workpieces were formed at different temperatures to find the best forming temperature. The results show that using the lubricant film of nickel matrix with MoS2 self-lubricating material, Ti-6Al-4V titanium workpiece was formed with high surface quality, and the optimum thickness of composite coating is 20 μm for Ti-6Al-4V titanium sheet of 1.0-mm thickness. In fact, the lubricant film also does help to prevent oxidation of Ti-6Al-4V titanium sheet. The appropriate temperature range of Ti-6Al-4V forming with slightly oxidized is 500–600°C in processing, and the maximum draw angle formed in this range was 72°.