Accuracy Evaluation of Dense Matching Techniques for Casting Part Dimensional Verification

Product optimization for casting and post-casting manufacturing processes is becoming compulsory to compete in the current global manufacturing scenario. Casting design, simulation and verification tools are becoming crucial for eliminating oversized dimensions without affecting the casting component functionality. Thus, material and production costs decrease to maintain the foundry process profitable on the large-scale component supplier market. New measurement methods, such as dense matching techniques, rely on surface texture of casting parts to enable the 3D dense reconstruction of surface points without the need of an active light source as usually applied with 3D scanning optical sensors. This paper presents the accuracy evaluation of dense matching based approaches for casting part verification. It compares the accuracy obtained by dense matching technique with already certified and validated optical measuring methods. This uncertainty evaluation exercise considers both artificial targets and key natural points to quantify the possibilities and scope of each approximation. Obtained results, for both lab and workshop conditions, show that this image data processing procedure is fit for purpose to fulfill the required measurement tolerances for casting part manufacturing processes.

3D Measurement Simulation and Relative Pointing Error Verification of the Telescope Mount Assembly Subsystem for the Large Synoptic Survey Telescope

An engineering validation of a large optical telescope consists of executing major performing tests at the subsystem level to verify the overall engineering performance of the observatory. Thus, the relative pointing error verification of the telescope mount assembly subsystem is of special interest to guarantee the absolute pointing performance of the large synoptic survey telescope. This paper presents a new verification method for the relative pointing error assessment of the telescope mount assembly, based on laser tracker technology and several fiducial points fixed to the floor. Monte-Carlo-based simulation results show that the presented methodology is fit for purpose, even if floor movement occurs due to temperature variation during the measurement acquisition process. A further research about laser tracker technology integration into the telescope structure may suggest that such laser tracker technology could be permanently installed in the telescope in order to provide an active alignment system that aims to detect and correct possible misalignment between mirrors or to provide the required mirror positioning verification accuracy after maintenance activities. The obtained results show that two on-board laser tracker systems combined with eight measurement targets could result in measurement uncertainties that are better than 1 arcsec, which would provide a reliable built-in metrology tool for large telescopes.

Traceability of On-Machine Tool Measurement: A Review

Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close measurements and fast feedback into their manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They provide the possibility to measure the workpiece in-machine during or after its manufacture, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable enough for process control or product validation. The scientific objective is to determine the uncertainty on a machine tool measurement and, therefore, convert it into a machine integrated traceable measuring process. For that purpose, an error budget should consider error sources such as the machine tools, components under measurement and the interactions between both of them. This paper reviews all those uncertainty sources, being mainly focused on those related to the machine tool, either on the process of geometric error assessment of the machine or on the technology employed to probe the measurand.

Synthesis and characterization of nanostructured PS-b-P4VP/Fe2O3 thin films with magnetic properties prepared by solvent vapor annealing

In this work hybrid organic/inorganic nanocomposites with magnetic properties, based on a PS-b-P4VP block copolymer and Fe₂O₃ maghemite nanoparticles have been prepared.

Effects of amine molecular structure on carbon nanotubes functionalization

Three amines with different molecular structure, triethylenetetramine (TETA) and two polyetheramines (Jeffamine D-230 and Jeffamine T-403) were employed to functionalize multi-walled carbon nanotubes (MWCNT) previously oxidized by acid treatment. The functionalized MWCNT were characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV-vis spectroscopy and the surface modification was investigated by field emission scanning electron microscopy (FE-SEM). Thermogravimetric analysis (TGA) was employed to quantify the amount of amine groups anchored to MWCNTs. The results have shown that the efficiency of amine functionalization is in the order TETA > D-230 > T-403, thus showing that amine chemical structure and molecular weight are important parameters on functionalization of carbon nanotubes.

Crystallization of poly(l-lactid acid) monitored by dielectric relaxation spectroscopy and atomic force microscopy

An investigation was carried out on the crystallization process of poly(l-lactid acid) by dielectric relaxation spectroscopy and atomic force microscopy. Experimental results were generated by dielectric relaxation spectroscopy over a wide range of frequency and temperature in both the wholly amorphous state and during crystallization. The variation of the average relaxation time was studied during crystallization at 80 degrees C and the temperature dependence of this relaxation time for wholly amorphous and crystallized samples was analysed. This behaviour was modelled by Havriliak-Negami and Vogel-Fulcher equations. The sensitivity of the segmental dynamics to the degree of crystallinity was analysed, taking into account the relaxing segments and the thickness of the amorphous layer between lamellae. The morphologies obtained during crystallization processes at 80, 130 and 150 degrees C were monitored by atomic force microscopy at both the lamellar level and by analysing the multilayered superstructures formed. Hedrites, intermediate structures between single lamellar crystals and mature spherulites, were found to appear at the highest temperatures, whereas no evidence of hedrites was found at 80 degrees C, the spherulites seemed to be constructed from a framework of individual dominant lamellae that splay apart and branch. Complementary to the atomic force microscopy study, the evolution of the obtained morphologies was also followed by optical microscopy. Supporting evidence about the thermal behaviour of the polymers was obtained with differential scanning calorimetry.