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Failure of a lancing system was investigated. A local company produces bridge slot screen filter pipes. Specific cutting tools, part of the lancing system, brake down repeatedly. The parts were manufactured from AISI D2 steel. A systematic investigation consisting of on site inspection, visual examination, dimensional verification, hardness measurements and chemical analysis was carried out. Samples were selected and prepared for destructive testing. The fracture surfaces and the cross section of the tools were analyzed by light and SEM microscopy. The tools failed due to high shear stresses, unevenly developed on the surface of the parts. Their breakage is mainly attributed to poor design. The cutting-forming system should be redesigned and some aspects regarding the machine use and maintenance should be specified. Additionally, alternatives regarding the material selection of the tools are provided in order to ensure efficiency and to improve operational reliability.

The failure of a motorbike fuel tank was investigated. Leakage of fuel was detected on the stabilizing subassembly at the front side of the base. The main container was replaced. The new container ended up leaking as well after only four months of use, proving that the failure was not a random incident. The study comprises visual examination, non-destructive testing by penetrant liquids, microhardness measurements and chemical analysis. Welded samples of the leakage area were investigated from macroscopic and microscopic perspective. The microstructure was analyzed by optical and scanning electron microscopy. Welding defects were found on the failure area. Most of them could be associated to inappropriate welding parameters. Hairline cracks were detected on resistance spot welding points. The cracks originated approximately at the center of the weld nugget, propagated through the weld zone, pierced the welding interface and reached the opposite sheet surface. Findings indicated interfacial failure mode. Poor welding process is considered the main cause of the failure and the specific sequence should be improved. Detailed practice recommendations and rigorous inspection are required to assure tank integrity. The tank tightness is of pivotal importance for the safe operation of the engine, the safety of passengers and protection of the environment.

A company produces truck wheel covers as spare parts for the local market. The production of these parts is based on a progressive die performing consecutive forming and selective cutting stages throughout the initial circular steel sheet. The failure occurred to the final stage of manufacturing, as the die marks, by mold-printing, the assembly configuration of the wheel cover onto the wheel rim. The paper presents a thorough failure analysis of the broken tool. The investigation includes preliminary examination, hardness measurements and chemical analysis. In depth microscopic examination was carried out using stereoscope and optical and electron microscopy. The failure mechanism was investigated from macroscopic and microscopic perspective and conclusions regarding the crack initiation and propagation were conducted and analyzed. The causes that led to the total fracture were discussed. The design of the tool and improper surface roughness are considered to be the main causes of the failure. Some complementary recommendations were proposed so to enhance the production rate of the specific tool.

The paper studies the fracture surfaces of a rotary cold working die that broke down during the setup process on the machine it was designed for. The die was manufactured using AISI D2 tool steel and was intended for cutting paper at room temperature. The tool failed during the setup process on the machine. Initially, historical data were collected: operating conditions, lifetime, restitution of sound operation, collection of recorded service history. This was followed by measurement of temperatures, hardness control, optical inspection and selection and preparation of samples. The cutting edges, fracture surfaces and the structure, not affected by the failure, were investigated by optical microscopy. The quality of the nitrated layers were inspected. Additional information concerning the fracture was obtained by examining the fracture surfaces using a scanning electron microscope. Local chemical analysis of the material was made using an EDX spectrometer. Fracture mechanism, the type of the fractures, and the principal causes that led to the premature failure of the die are discussed. Justification of these causes facilitates the prevention of future failures and sometimes contributes to an increased service life of the tools.

Failure analysis investigates the causes of a product’s destruction. Its final objective is to suggest measures that can be taken in order to prevent or minimize the chance of failure in the most economical way. This paper studies the failure of a rotary cold working die. The tool was manufactured from AISI D2 tool steel and it was intended for cutting paper at room temperature. The tool failed during the setup process on the machine it was designed for, thus failing to commence the manufacturing process. The process was initiated by a crack that began at the point of a diameter change of the tool body in the attachment part, where the tool was fastened to the rest of the machine. This paper presents the first results of the die failure study. Historical data were collected: operating conditions, lifetime, restitution of sound operation, collection of recorded history, measurement of operating temperatures and hardness control. This was followed by optical inspection, selection and preparation of samples and macroscopic analysis of fracture surfaces. The paper presents conclusions on the fracture mechanism and form and suggests the first probable causes leading to die failure. The results could be useful for industry as regards the avoidance of such failures in the production process.

This paper studies the fracture surfaces of an aluminium hot extrusion die that broke down during operation. The die was constructed, from H13 steel and was intended for the production of 60,000 Kg of aluminium profile. The male part fractured during operation after the production of 500 Kg profile. Initially, the machine and thermal treatments that were applied for construction of the die were collected and studied. The die was carefully inspected visually with a stereoscope. The fracture surfaces, some cracks, and the structure that was not affected by the failure, were investigated by optical microscopy. The thickness, quality and homogeneity of the nitrated layers were inspected. Additional information concerning the fracture was obtained by examining a primary crack using a scanning electron microscope and chemical analysis of the material was made using EDX attachment. The paper reports on some interesting observations relating to the fractured component, the type of the fractures, and the quality of the heat treatments, and presents some of the probable causes that led to the premature failure of the die.