Mladen Šercer

Mathematical model for the selection of processing parameters in selective laser sintering of polymer products

Additive manufacturing (AM) is increasingly applied in the development projects from the initial idea to the finished product. The reasons are multiple, but what should be emphasised is the possibility of relatively rapid manufacturing of the products of complicated geometry based on the computer 3D model of the product. There are numerous limitations primarily in the number of available materials and their properties, which may be quite different from the properties of the material of the finished product. Therefore, it is necessary to know the properties of the product materials. In AM procedures the mechanical properties of materials are affected by the manufacturing procedure and the production parameters. During SLS procedures it is possible to adjust various manufacturing parameters which are used to influence the improvement of various mechanical and other properties of the products. The paper sets a new mathematical model to determine the influence of individual manufacturing parameters on the polymer product made by selective laser sintering. Old mathematical model is checked by statistical method with central composite plan and it is established that old mathematical model must be expanded with new parameter beam overlay ratio. Verification of new mathematical model and optimization of the processing parameters are made on SLS machine.

Influence of hybrid mould on moulded parts properties

Purpose – This paper aims to emphasize compared experimental analysis of influence of hybrid and classic moulds on the properties of moulded parts and the processing parameters. Such analysis enables optimization of processing parameters in case of the hybrid mould.Design/methodology/approach – Representative moulded part and appropriate hybrid and classic moulds have been designed and manufactured. The experimental work contains a screening design and the main central composite design for analysing the performance of both moulds and moulded parts properties. In case of hybrid mould a numerical optimization of processing parameters was used.Findings – It was found that hybrid moulds can be successfully applied for production of thin‐wall moulded parts with some limitations. The compressibility of prototype mould inserts was higher compared to classic inserts. The differences in thermal properties of mould inserts materials result in different moulded part properties and mould cavity wall temperature field...

Influence of SLS processing parameters according to the new mathematical model on flexural properties

Purpose The purpose of this paper is the selection of production parameters in selective laser sintering – SLS for the production of quality products (e.g. good mechanical properties). The manufacturing procedure affects the properties, which is especially significant in additive procedures, as the products are not cheap and the procedure and material need to be optimally selected. Design/methodology/approach The paper presents an analysis of the fabrication parameters in selective laser sintering (SLS) that affect the flexural properties of the finished product. Findings The influence of a new parameter has been found, the overlay ratio, and using the mathematical and scheme method, the selection of parameters for obtaining the optimal flexural properties has been proposed. Originality/value The paper presents a new mathematical model for the calculation of the processing parameters in SLS of polymer products and gives a diagram for the determination of which parameters are the best to use for practical purposes.

Application Of Moldex3D For Thin‐wall Injection Moulding Simulation

The benefits associated with decreasing wall thicknesses below their current values are still measurable and desired even if the final wall thickness is nowhere near those of the aggressive portable electronics industry. It is important to note that gains in wall section reduction do not always occur without investment, in this case, in tooling and machinery upgrades. Equally important is the fact that productivity and performance benefits of reduced material usage, fast cycle times, and lighter weight can often outweigh most of the added costs. In order to eliminate unnecessary mould trials, minimize product development cycle, reduce overall costs and improve product quality, polymeric engineers use new CAE technology (Computer Aided Engineering). This technology is a simulation tool, which combines proven theories, material properties and process conditions to generate realistic simulations and produce valuable recommendations. Based on these recommendations, an optional combination of product design, material and process conditions can be identified. In this work, Moldex3D software was used for simulation of injection moulding in order to avoid potential moulding problems. The results gained from the simulation were used for the optimization of an existing product design, for mould development and for optimization of processing parameters, e.g. injection pressure, mould cavity temperature, etc.

Impact of ageing, different share of recycled material and orientation on SLS polyamide product hardness

In selective laser sintering (SLS) of polymer products the price of material is not the most important factor, but it does play a significant role when analysing the overall i.e. final price of the product, and therefore recycling of material is becoming an increasingly important factor, as well as the ratio of the shares in combining the original and the already used materials. In practice it is inevitable to use the products in various atmospheric conditions (UV radiation and humid environment), intentionally or unintentionally. UV light, with sun being its most common source, and average humidity in different parts of the world can be approximately from 20% to 90%, depending on time, day and geographic location. Therefore, it is necessary to determine how UV light after a longer period of time of exposure affects the product properties. The properties of the final product are also affected by the orientation in the working area of the machine. In the paper an analysis has been performed of the impact o...

Performance comparison of low-budget 3D printers

Additive technologies have begun its development and application since the second half of the 1980s. The main reason behind that was to fulfil the market demands of increased product quality, flexibility, lower costs, shorter development time and production, as well as small series and individual production. As part of additive technologies, low-budget 3D printers have been developed and are widely available now, and they have enabled a significant expansion of the application of additive technologies for development and production. A large number of low-budget 3D printers on the market make it difficult for the potential investor to choose from. Therefore, potential investor in low-budget 3D printers has to know more detailed their working principle, their construction, materials that they can process and the errors and problems of their technology that occur during processing. In the paper, two most popular low-budget 3D printers MakerBot Replicator 2X and Ultimaker Original was chosen for a detailed co...

STUDY ON THERMAL PROPERTIES OF SYNTHETIC AND BIO-BASED POLYURETHANE

Polymers that are created by the chemical polymerization of naturally occurring monomers are attracting considerable commercial interest in the last few years because of their non-toxicity, biodegradability and biocompatibility and use of feedstock that is renewable. The development of specialized lignin compounds, such as electrically conducting polymers, engineering plastics and polyurethane, is an area of highest interest and growth. The paper will present the comparison of the mechanical and thermal properties of conventional polyurethane and bio-based polyurethane, i.e. polyurethane based on polyols produced by liquefaction of waste wood biomass.