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The study examines the dramatic drop in the efficiency of a cutting tool. The specific tool is part of machine used for cutting envelopes of paper for medical products packaging. Two similar pieces, selected after breaking down in service, were examined in depth. Historical data was collected. The tool temperature range during operation and the material hardness were measured. The fracture surfaces as well as the surrounding areas were carefully inspected. Chemical analysis was performed in order to identify the tool and coating materials. Results showed that components were made of different steels: D2 and Vanadis 6. The coating material also differs. Samples were selected and prepared for optical and electron microscopy. The condition of the cutting edges and the heat-treated microstructure were considered. Thickness, quality and homogeneity of the coatings were also inspected. Both tools failed by fatigue mode under different conditions. The fracture mechanism and its principal causes are discussed. The reasons of failure for both cutting tools are examined and compared. Poor designs associated with improper handling have led to the components breakage. Appropriate recommendations are given in order to eliminate similar situations and to improve the cutting performance.

The reactivities of various fatty monoacids and diacids on copper metal-containing surfaces were investigated through reflection-absorption infrared spectroscopy. The formation of copper soaps is detected on pure copper surfaces, while copper and zinc soaps are simultaneously formed as mixtures on brass surfaces. Following the changes of acidic carbonyl and carboxylate infrared bands, it is shown that fatty monoacids C8, and C10 react with clean/polished copper and its zinc alloy within 2–4 hours, while those with chains > C12 react within 15–40 days. An explanation for the above results is offered on a molecular mobility basis, where liquid monoacids at room temperature favour higher reaction rates. Furthermore, it is argued that longer-chain FMAs allow for favourable orientation resulting in self-assembled monolayer (SAM)-type molecular packing on Cu surface, may explain the slower reaction. Fatty diacids, on the other hand, do not form any carboxylate products under these conditions. In light of this interesting result, it is argued that dicarboxylic acids may also pack as self-assembled layers on Cu and ultimately protect it. The implications for fatty organic remains in copper containers are discussed, with emphasis on the stability of archaeological copper metal and carboxylates serving as molecular markers for the presence of fatty monoacids as residues in archaeological containers. Besides, the utilization of fatty acids, based on the above behaviour in copper-based dosimeters, such as those used in the Oddy test, is suggested.

DIN 15CrNi6 is the most representative grade of the case-hardened steels. The present work analyses the influence of carburizing time on hardness of the specific steel. Specimens with similar chemical composition were heated at 900°C in liquid carbonaceous media for one, two, three and four hours, correspondingly. Then samples were oil quenched and tempered at 180°C for two hours. Microhardness was measured across the carburized zone and case profiles were acquired. The effective case depth was determined as function of carburizing holding time. Core macro hardness was carried out and the impact of holding time on the substrate hardness was discussed. The optimum case depth was defined and the carburizing parameters determined. The hardness control is critical in case hardening practice and results provide practical information to heat treaters, useful both to control the treatment parameters and to minimize the risk of failure.

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