The use of additive technologies keeps growing. Increasingly, flammable powder materials are also used in additive technologies, and there is a risk of explosion or fire when using them. The current article deals with the determination of fire parameters of a powder sample of polyamide Sinterit PA12 Smoth in accordance with the EN 14034 and EN ISO/IEC 80079-20-2 standards. For that purpose, a sample at a median size of 27.5 µm and a humidity of 0% wt. was used. The measurements showed that the maximum explosion pressure of the PA12 polyamide sample was 6.78 bar and the value of the explosion constant Kst was 112.2 bar·m·s−1. It was not possible to determine the MIT value of the settled dust, since the melting point of polyamide sample is low. The MIT of the dispersed dust was 450 °C. Based on the measured results, it can be stated that the powdered polyamide PA12 poses a risk in terms of explosions and fires. Therefore, when using polyamide PA12 in additive technologies, it is necessary to ensure an effective explosion prevention.
The paper is focused on additive manufacturing (AM) which is the process of producing objects from a three-dimensional (3D) model by joining materials layer by layer, as opposed to the subtractive manufacturing methodologies [1], directly from raw material in powder, liquid, sheet, or a filament form without the need for moulds, tools, or dies. The article demonstrates potential environmental implications of additive manufacturing related to the key issues including energy use, occupational health, waste and lifecycle impact. AM provides a cost-effective and time-efficient way to fabricating products with complicated geometries, advanced material properties and functionality. Based on this review, we identified that additive manufacturing will have a significant societal impact in the near future. A critical technical review of the promises and potential issues of AM is beneficial for advancing its further development.
Measurement by computed tomography is very useful in evaluation of dimensions and internal structure. There are still some problems which need to be solved. Scanning accuracy depends, among other things, on the part´s material. Metal parts have high density and their scanning leads many times to failure. This paper deals with evaluation of accuracy of seamless steel tube scanning by industrial computed tomography. This method of scanning can lead to substitution of destructive method for measurement, but it is necessary to have knowledge if the scan has required accuracy. The tube with different diameters in length is scanned by X-Ray beam and it is evaluated inner and outer diameter, concentricity and wall thickness in 8 sections. The accuracy of scan is compared with reference values achieved by coordinate measuring machine in the same sections.
During the drilling process of the aluminium alloy, certain specifications are different from milling and turning. The major differences: 1) a variable cutting speed along the main cutting edge, 2) more difficult chip evacuation, 3) poor access of liquids into the cutting area. One of the problems is to select a suitable cutting environment for drilling the aluminium alloy to ensure the required quality of the bore (mainly roughness and cylindricality). Dry drilling of aluminium alloys (without using cutting fluids) is an environmentally friendly machining process but also an extremely difficult task due to the tendency of aluminium to adhere to the drills made from conventional materials such as high-speed steel, therefore three cutting environments (namely two different emulsions and compressed air) were used this experiment. The paper is focused on the experiment where the effects of the cutting environment and feed of machining on the bores roughness and cylindricity are evaluated. The article demonstrates multicriterial optimization of input factors (cutting environment, feed) for two defined target functions roughness and cylindricity). The measured values were subjected to mathematical statistical analysis Desirability Function Analysis (DFA). Based on the experiment and studies on this issue combinations of input factors have been identified that have achieved minimum target function values. The results show that the most appropriate combination of the following input factors has been demonstrated: compressed air and feed setting at the lowest level, ie 0.2 mm.
The main paper idea was compared three methods (Contact CenterMax and contactless ATOS TripleScan II, Metrotom 1500) for data acquisition to the output characteristics of steel drawing tubes. Outer and internal diameters, eccentricity and ovality were measured. Steel tubes produced by drawing should accomplish shape and dimensional characteristics. These can be measured by various contact and contactless methods. Each of these methods have advantages and disadvantages. The computed tomography advantages are, that we obtain both outer and inner tube shapes. Output is a 3D model from which you can get the elements to evaluate the characteristics. The data acquisition is limited by wall thickness and material density and that is disadvantage. The 3D scanner advantages are, that we obtain outer tube shapes with different diameters and wall thickness regardless of material density. Output is a 3D model. Problem is to obtain data about complex internal shape limited by tube length and diameter and that is the disadvantage. The advantage of acquiring data by contact method is that we obtain both external and internal tube shape, without thickness wall, diameter or material density limitation. The disadvantage is that we don´t obtain a 3D model of tube, but only a spot-scanned elements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.