Proceedings of the 37th International MATADOR Conference

The purpose of the present study is to investigate process capability of hybrid investment casting (HIC) for industrial applications. Starting from the identification of component, prototypes were prepared as replicas of plastic patterns (by hybridization of fused deposition modelling and conventional investment casting). Some important mechanical properties were also compared to verify the suitability of the components. Final components produced are acceptable as per ISO standard UNI EN 20286-I (1995). The results of study suggest that HIC process lies in ±4.5sigma (σ) limit as regard to dimensional accuracy of component is concerned. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.

Current solutions in Computer Aided Process Planning (CAPP) can be time consuming, complex and costly to employ and still require the input of an experienced planner. Implementations can require a high degree of configuration, particularly when preexisting knowledge within the company needs to be incorporated. This means due to the time and expense many companies, particularly smaller ones, do not employ CAPP systems. Within the process planning domain of machining, decisions need to be made regarding routing and processes, with each choice making a significant impact on the final cost and quality of the product. Existing CAPP systems need to be carefully configured as they rely on artificial intelligence or existing data to find the best routes and processes. These systems tend to be very specialised and their configuration can be tper presents a prototype haptic virtual machining application where machining operations are simulated whilst visual and tactile information is fed back to the operator to enhance their experience. As they generate their maching sequence the operator input is logged. By logging their activities it is shown that specialist knowledge can be accumulated unobtrusively and formalised such that the system can immediately generate usable process plans without the need for lengthy configuration and formalisation. Experimental findings show how using a virtual reality (VR) environment can clearly represent a machining task and that relevant knowledge and data can be quickly captured during a simulation. Simulating machining tasks in this way offers a unique non-intrusive opportunity to collect important information relevant to a machining process; this information can then be used further downstream during manufacturing.

Metal matrix composites (MMCs) have found many successful industrial applications in recent past as high-technology materials due to their properties. Wire electric discharge cutting (WEDC) process is considered to be one of the most suitable processes for machining MMCs. Lot of research work has been done on WEDC, but very few investigations have been done on WEDC of MMCs. This paper reports work on the analysis of material removal rate (MRR) and cutting width (kerf) during WEDC of 6061 Al MMC reinforced with silicon carbide particles (i.e. SiCp/6061 Al). Four WEDC parameters namely servo voltage (SV), pulse-on time (TON), pulse-off time (TOFF) and wire feed rate (WF) were chosen as machining process parameters. Artificial neural network (ANN) models and response surface methodology (RSM) models were developed to predict the MRR and kerf using Box-Behnken design (BBD) to generate the input/output database. It was observed that prediction of responses from both models closely agree with the experimental values. The ANN models and RSM models for WEDC of MMC were compared with each other on the basis of prediction accuracy which shows that ANN models are more accurate than RSM models for MRR and kerf because the values of percentage absolute errors are higher for RSM models than ANN models.

Communicating the knowledge and science of product engineering, analysis and manufacturing planning is an area of continued research driven by the digital economy. Virtual Reality (VR) is a generally accepted interactive digital platform which industry and academia have used to model engineering workspaces. Interactive services that generate a sense of immersion, particularly the sense of touch to communicate shape modelling and manipulation, is increasingly being used in applications that range from Design For Manufacturing and Assembly (DFMA) and Process Planning (PP) to medical applications such as surgical planning and training. In simulation, the natural way for solid modelling is the use of primitive geometries, and combinations of them where complex shapes are required, to create, modify or manipulate models. However, this natural way makes use of Booleans operands that require large computational times which make them inappropriate for real time VR applications. This work presents an insight on new methods for haptic shape modelling focused on Boolean operands on a polygon mesh. This is not meant as a contrast to point/meshediting methods, instead it is focused on idealising polygonal mesh modelling and manipulation for use with haptics. The resulting models retain a high level of geometric detail for visualisation, modelling, manipulation and haptic rendering.

Nickel-based alloys are frequently applied in the aerospace and power generation industries due to their excellent material properties, such as high temperature strength and high corrosion resistance. These advantageous material properties, however, result in challenges for cutting operations. Contrary to turning, where good results for the machining of nickel-based alloys have been obtained, drilling processes are less investigated until now. In general, coated cemented carbide drills have been proven to show good performances in drilling operations based on their higher strength compared to high speed steel (HSS) tools. Hence, they can be utilized with more efficient process parameters, whereby tool life will likely be reduced as a consequence of the higher loads. In order to find reasonable trade-offs between efficiency and tool life, a multi-objective optimization based on both criteria is presented in this article. The optimization of the cutting parameters is performed for drilling the popular nickel-based alloy Inconel 718. It is assisted by empirical models based on statistical experimental design techniques. By these means, the trade-off surface between process efficiency and tool wear can be approximated within a small experimental effort. In addition, the dominant mechanisms behind the tool wear for different process parameters are discussed.

This paper compares the simulation and experimental results for robust part handling by radially symmetric cylindrical electromagnetic gripper heads, that are used in foundry manufacturing assembly operation. Knowledge of the direct holding force is essential to determine if a given electromagnet is capable of preventing part slipping during pick and place operation. Energy based model and the magnetic circuit model have been described. The latter is developed further and compared with results from a FEA software. It was found that the magnetic circuit model, although simple in form, was limited in its ability to accurately predict the holding force over the entire range of conditions investigated. The shortcomings in the model were attributed to its inability to accurately model the leakage flux and non-uniform distribution of the magnetic flux. A finite element allowed for the ability to couple the mechanical and magnetic models. The finite element model was used to predict the magnetic field based off the solutions to the mechanical (σ ) and the magnetic model (B).

The measurement of structure dynamics is a common technique to characterise the dynamic behaviour of structures, analysing reasons of disturbing vibrations, design optimization and as comparison data to check and improve simulation results. Depending on the measurement task, different measurement devices are used such as laser vibrometers and accelerometers. A recent approach is to perform modal analyses using a trackinginterferometer. Firstly the fundamentals of vibration measurement and modal analysis with tracking-interferometers are discussed. Due to the adaption of the measurement device from geometry measurement to vibration measurement several issues have to be considered. Two of them are focused in this paper. The first discussed issue is the influence of the connection of the targets and nests to the vibrating structure. Moreover, for an automation of modelling of the machine it is necessary to measure the absolute distance between tracking-interferometer and the target mounted at the structure. Due to the fact that the used LaserTRACER does not have an absolute distance measurement unit, alternative methods to acquire the absolute distance information out of the signals of the available position sensitive diode are presented.

Projection microstereolithography(PμSL) has some advantages such as precision of several μm, fast fabrication time, and simple fabrication process for complete 3D micro-structure. However, the application of PμSL has limitation due to the liquid material, compared with other additive manufacturing (AM) technology such as fused deposition modeling (FDM) and selective laser sintering (SLS). In this study, we propose the material switching system (MSS) to fabricate a multi-material biomicrostructure in PμSL. The system consists of three control modules; resin level control (RLC), resin dispensing control (RDC), vat level control (VLC). To evaluate the performance of the MSS, the accuracy of resin level has been measured before and after resin exchange. Then, several fabrication methods to reduce the error due to the MSS have been presented. For the application of this system, biodegradable and biocompatible materials have been synthesized and the mechanical and curing properties have been investigated. Several bio-structures of multi-material such as scaffold and transdermal drug delivery system (TDDS) have been fabricated.

Adaptively controlled hybrid laser-arc welding has been demonstrated using a 5kW 6mm.mrad Yb fibre laser. ISO 13919-1 class B (stringent) quality butt welds have been made in 4mm Al alloy, 6mm stainless steel and 8mm thickness steel plates. A laser vision sensor, used to track the joints robotically during welding, sends joint fit-up information (gap width and mismatch height) to a controller. This adjusts, in real time, the welding parameters to increase the net tolerance of hybrid welding, particularly to joint gap. Stringent quality welds can be made over a wider range of joint fit-up cases than using fixed conditions.

Selective Laser Sintering, and in general Additive Manufacturing Processes are becoming mature technologies; in the sense that after many years of market introduction there are some well-known manufacturers that provide fully operative systems that are even utilized for direct parts manufacturing. However, the parts final users are becoming more and more demanding, so they can integrate the AM parts in complex assemblies; thus increasing the materials requirements and the final part’s properties. Building into previous works on AM materials, the purpose of the present paper is to explore the properties yielded by the introduction of Glass short fibre randomly to polyamide and to assess the performance of the probe parts taking into consideration the AM manufacturing direction in the building platform and the Energy Density applyied to the operations. Folowing to a literature review, the paper first describes the statistical approach and the samples preparation. Then, the samples are characterized by tensile tests and the properties of the material are described for the different manufacturing strategies adopted. The outcomes of the work are highly applicable to the AM parts manufacture process, as the construction of parts in the building platform is usually dictated by the objective of optimizing the use of the total volume; thus implying that not all parts are manufactured in the same main construction direction.

An attempt was made to predict the density and microhardness of a component produced by Laser Sintering of EOS DM20 Bronze material for a given set of process parameters. Neural networks were used for process-based-modelling, and results compared with a Taguchi analysis. Samples were produced using a powder-bed type ALM (Additive Layer Manufacturing)-system, with laser power, scan speed and hatch distance as the input parameters, with values equally spaced according to a factorial design of experiments. Optical Microscopy was used to measure cross-sectional porosity of samples; Micro-indentation to measure the corresponding Vickers’ hardness. Two different designs of neural networks were used - Counter Propagation (CPNN) and Feed- Forward Back-Propagation (BPNN) and their prediction capabilities were compared. For BPNN network, a Genetic Algorithm (GA) was later applied to enhance the prediction accuracy by altering its topology. Using neural network toolbox in MATLAB, BPNN was trained using 12 training algorithms. The most effective MATLAB training algorithm and the effect of GA-based optimization on the prediction capability of neural networks were both identified.

In this paper, the WC-10Co4Cr coatings were deposited by the laser hybrid plasma spraying (LHPS) technology on the 38CrMoAl substrate. Microstructures, tribological characteristics and corrosion-resistance performance of the coatings were studied using an optical microscope, an X-ray diffraction, a scanning electron microscope, an SRV friction and wear tester and the Neutral Salt Spraying (NSS) test. Test results indicated that LHPS WC- 10Co4Cr coating had good wear-resistance and corrosion-resistance performance comparing with the base material. The LHPS coating overcame many defects of the conventional spraying coatings such as poor bonding strength, many pores and many cracks. LHPS is able to improve the bonding strength as the interfaces are melted and joined by the laser simultaneously with plasma spraying. The coating achieves metallurgy bonding and its microstructure becomes more compact and therefore its performances are greatly improved.