Dan Leordean

Selective laser melting of Ti6Al7Nb with hydroxyapatite addition

Purpose – The purpose of this paper was to obtain by means of selective laser melting and then characterize biocomposites of medical-grade Ti6Al7Nb with hydroxyapatite (2 and 5 vol.%) and without hydroxyapatite, as reference. Design/methodology/approach – Rectangular samples were manufactured with the same scanning strategy; the laser power was between 50 W and 200 W. Processed samples were analysed by means of optical microscopy, scanning electron microscopy and microhardness. Findings – The results showed that despite the very short processing times, hydroxyapatite decomposed and interacted with the base Ti6Al7Nb material. The decomposition degree was found to depend on the applied laser power. From the porosity and bulk microstructure point of view, the most appropriate materials for the purposed medical applications were Ti6Al7Nb with hydroxyapatite processed with a laser power of 50 W. Originality/value – The originality of the present work consists in the study of the behaviour and interaction of hy...

Research on Producing Complex Metal Parts with Lattice Structure by Selective Laser Melting

This study evaluates the manufacturability and performances of periodic cellular lattice structures designed by repeating a cubic unit cell and produced by SLM using titanium powder. The effects of unit cell size on the manufacturability, density, compression and bending properties of the manufactured cellular lattice structures were investigated. Lattice structures manufactured with various unit cell sizes ranging from 0.5 to 1.2 mm could be produced free of defects by the SLM process, with a novel type of supports. By the increasing of the cell size, a decrease of the applied load together with an enhancement of the flexure extension were observed. Specimens with a cell size higher than 1 mm manifested an excellent flexibility by flexure tests.

Design and Analyses to Determine the Minimum Acting Force of a Gripper for Handling the Parts with Robots

This paper presents a model of gripper designed for KUKA robot, together with a series of static and dynamic analyses for different loadings of it. Both the 3D design and static and dynamic analyses have been conducted using the design of Creo package with Parametric and Simulate the modules. The Gripper designed has in its composition a mechanism type rack-pinion type and a quadrilateral mechanism, for carrying out a parallel movement of jaw. It was determined the minimum force of actuation of the pinion-rack mechanism of gripper for maintaining the piece caught in gripper jaws, at the maximum speeds of rotation of the robot.

Studies Regarding Redesign and Optimization of the Main Shaft of a Naval Winch

This article presents the results of a study regarding the structural optimization of the main shaft of a naval winch and its manufacturing technology. Throughout this paper, its design will also be changed and improved. The main purpose of the research here described is to reduce the mass of the shaft from an initial weight of 23 kg. The drum responsible for releasing the boats in the water is placed on the first section of the spindle. The maximum embarkation is 2141 kg (21kN), meaning the safe working load of the davit, consisting in a boat fully equiped with 10 people in it. Moreover, this value of 2141 kg, is multiplied with the safety factor of a minimum 4.5, specific for the maritime industry, in the proceeded analyzes. The other objectives of the study take into consideration the fulfiling of the functional role without having a major intervention upon the other components of the winch, the reduction of costs and the decreasing in manufacturing time. Therefore, starting from a hollow byproduct, through the processes of optimization, redesign and simulation using finite element analysis, the achieved results show a 45% reduction in the weight of the shaft and a significant shortage of the manufacturing time. In this entire proceess, only one component needs technological changes by repositioning its 4 holes. From the economical point of view, by using a tube instead of a bar, it is possible a reduction of almost 6000 USD for a batch of 1000 shafts.