Anjali K.M. DeSilva

Modelling and Experimental Investigation of Laser Assisted Jet Electrochemical Machining

Abstract Laser Assisted Jet Electrochemical Machining is a hybrid process which combines a relatively low power laser (375mW) with an electrolyte jet to facilitate metal removal. The main purpose of the laser is to enhance the localisation effect of electrochemical dissolution from the workpiece, thus giving better precision and machining efficiency. The laser thermally activates the material surface where it impinges thereby increasing the electrochemical current density in that localised zone. A theoretical model is used to explain the effects of localisation of electrochemical dissolution process. Experimental analysis using aluminium alloy and stainless steel has proved that laser assistance can yield up to 54% higher volumetric rate and up to 38% better accuracy than using electrolytic jet alone.

Precision Mold Manufacturing for Polymer Optics

Ophthalmic lenses, sensors, and sunglasses, among other things, are commonly made of polymer materials. Therefore, polymer optics is a growing market mainly for medium quality but also for precision optics. Polymer optics are usually produced in an injection molding process. Due to high quality requirements on the final product, the manufacturing process of the molds has to be very accurate and precise. Thus the master tool has to be fabricated to a high quality with regard to shape accuracy and roughness. The focus of this article is on the process chain for the fabrication of molds for polymer optics and the finite element simulation of this process. The typical existing process chains contain steps like nickel plating, diamond machining and manual polishing. Some of these steps are expensive and require very experienced staff. In the new process chain, an industrial robot with special tools is used for lapping and polishing. Robot polishing replaces the former nickel plating, diamond machining, and manual polishing steps. The lapping/polishing process was newly developed to achieve appropriate results. Different tool materials, polishing agents, and process parameters have been tested and compared to the finite element simulation to obtain excellent results directly on different mold materials.

Influence of different polishing materials in the material removal of steel samples

Abstract The quality of injection moulded polymer optic parts depends on the surface finish of the respective mould. In order to improve and control the surface finish of the mould it is important to be able to keep the material removal constant during the polishing process of these moulds. This will provide a tactical material removal therefore allowing a controlled correction of the mould’s surface geometry. The aim of this work is to study the influence of different polishing materials in the material removal rate and its reproducibility during the polishing process of hardened steel. Different polyurethane polishing materials with different fillers were tested. It was observed that the filler material of the polyurethane is crucial in order to obtain constant and reproducible results. Experiments were carried out with an industrial robot and the material removal’s depth value was compared.

Material removal simulation for steel mould polishing

Abstract The surface finish of an injection mould influences the quality of the moulded polymer optic parts. In order to improve and control the surface finish of the mould it is important to be able to predict the material removal during the polishing process of this mould. The aim of this work is to predict the material removal during the polishing process, comparing the results obtained from polishing attempts on steel samples and the results obtained from a simulation model. A simulation model is developed with the abrasive wear Holm-Archard equation in ANSYS. This simulation model will help to eliminate the iterative trial and error polishing, therefore facilitating the steel mould production.

Alignment model for trunk road network maintenance outsourcing

Abstract.Road maintenance outsourcing is now the foremost strategy by which road authorities procure maintenance works. Despite growing application of road maintenance outsourcing, there are conflicting estimates on the effectiveness of road maintenance outsourcing and shortage of appropriate models to align over optimistic expectations of road authorities from road maintenance outsourcing with substantiated benefits. This paper investigates the efficacy of road maintenance outsourcing. In this paper, the different variants of road maintenance outsourcing and road maintenance works are evaluated with a SWOT analysis and a comprehensive literature review respectively. In addition, a road maintenance outsourcing alignment model based on a decision tree and Balance Score Card is proposed and illustrated with a Nigerian trunk road network authority as a case study. The result of the SWOT analysis and comprehensive literature review establishes fresh insight into road maintenance outsourcing dynamics. The pres...

A Study on Automating Rolling-stock Maintenance in the Rail Industry using Robotics.

Maintenance cost of United Kingdom’s rail rolling stock is a substantial portion of its whole life costs. Therefore, it is vital to conduct these maintenance tasks in an efficient and cost-effective manner to minimize operational costs while maximizing safety, quality, and consistency of service. The introduction of robotics and other intelligent mechanisms to maintenance processes would be an ideal solution to these challenges. Hence, this research suggests introducing autonomous maintenance systems equipped with industrial robots to tasks within the railway system, specifically for rolling-stock maintenance. The paper summarizes on-going and future work of a case-study conduct in conjunction with a UK railway operator.

FEM simulation of the material removal in pad polishing

Polishing as a step of the manufacturing process is not only used in the finishing of optical elements made out of glass. An increasing number of applications needs shiny or glossy surfaces. For these parts, the specified roughness has to be achieved by a final polishing step while keeping or improving the final shape. The goal of the presented research is to predict the material removal that occurs during the polishing process by a simulation based on finite element modelling (FEM). The presented finite element simulation model for PMMA is based on the material parameters for workpiece and polishing tool. Compared to previous research on aspherical elements made out of glass [1], the model allows the description of the process based on material parameters get out the data sheets. The data derived from the finite element modelling is compared with the polishing results on plastic materials (PMMA). Results of the polishing tests compared with the simulated values will be reported.