Forging dies are crucial in forging to manufacture accurate workpieces. These dies are generally made of AISI H steel series and hardened and tempered medium carbon alloy steel. Dies are processed by using high-speed milling + polishing or electrical discharge machining + polishing. The surface quality of the workpiece depends on the surface properties of these dies, where surface roughness, material hardness, and wear evolution of their surfaces are critical aspects to consider. This research analyzes different wire electrical discharge machining surface conditions combined with polishing treatment to describe their influence on friction and wear. Wire electrical discharge machining defines the disks’ surface properties in finishing and roughing conditions, and polishing treatment varies in time and paper sand depending on the roughness. Abbott-Firestone curves and Rsk-Rku roughness parameters characterize the surface roughness of each studied configuration. Room temperature pin-on-disk tests were performed to analyze friction coefficients and wear rate for AISI 1045 pins and AISI H13 disks. On average, the highest (0.284) and the lowest (0.201) friction coefficients were found for the combination of finishing wire electrical discharge machining + polishing and roughing wire electrical discharge machining conditions, respectively. Scanning electron microscope images were taken to describe the wear tracks and pin degradation for different sliding abrasive configurations. The diagram correlating the surface morphology and the friction coefficient predicts the wear damage on initial surface conditions, which is crucial in the forging industry to determine tool maintenance or replacement.

Railway spike screws are manufactured by hot forging on a massive scale, due to each kilometer of railway track needing 8600 spike screws. These components have a low market value, so the head must be formed in a single die stroke. The service life of the dies is directly related to the amount of energy required to form a single screw. The existing standard for spike screws specifies only the required tolerances for the head dimensions, particularly the angle of the hub faces and the radius of agreement of the hub with the cap. Both geometrical variables of the head and process conditions (as-received material diameter and flash thickness) are critical parameters in spike production. This work focuses on minimizing the energy required for forming the head of a railway spike screw by computational simulation. The variables with the highest degree of incidence on the energy, forging load, and filling of the die are ordered statistically. The results show that flash thickness is the variable with the most significant influence on forming energy and forming load, as well as on die filling. Specifically, the minimum forming energy was obtained for combining of a hub wall angle of 1.3° an as-received material diameter of 23.54 mm and a flash thickness of 2.25 mm. Flash thickness generates a lack of filling at the top vertices of the hub, although this defect does not affect the functionality of the part or its serviceability. Finally, the wear is mainly concentrated on the die splice radii, where the highest contact pressure is concentrated according to the computational simulation results.

Manufacturing molds for plastic parts injection are a particular machining domain, where challenging materials, like AISI P20 steel, are forced to satisfy the highest surface quality requirements. Before mirror polishing, milling operation is a common and challenging task due to drilling and milling with the same tool. Thus, special cutting tools, like asymmetric indexable type, are often used. This tool presents two geometrically equal positive inserts -one placed horizontally and the other vertically -for the flexible machining of holes, cavities, floors, and walls. Rough-medium milling operations lead to a complicated relationship between cutting conditions and geometrical tool parameters, making it challenging to balance the tool life of both inserts. The novelty of this work is to propose a model for cutting force prediction with an asymmetric tool to explain the separated behavior of both inserts and determine a better compromise between cutting conditions and tool life. The experimental tests were done for model validation and then wear cutting tests for testing improved cutting conditions. The results predicted by the model proved that by changing the depth of cut from 0.3 mm to 0.8 mm, the wear in both inserts was more balanced, increasing chip volume up to 1.7 times.

Automotive car companies are using AHSS (advanced high strength steels) over the last 20 years, to reduce vehicle weight and improve safety. The new steels can achieve higher strength and good fatigue resistance, but some issues related to springback and low formability are also a big concern. Thus, companies need to extend their know-how regarding material behaviour, design rules and manufacturing processes. Therefore, materials characterization laboratories are working to obtain the new formability charts of the steels. The grid laser marking of test pieces is a recent approach. However, the marking process must accomplish three main aspects: indelibility during the tensile testing procedure, precision, and of course, it must not affect the mechanical properties of studied steels. This work is focused on the laser marking of test pieces, using Ytterbium fiber laser. A dual phase steel (JFE CA 1180) is studied. Process parameter are defined. Keywords: grid marking, laser, advanced high-strength steels, AHSS, formability diagrams, mechanical properties