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Safety in Rough Milling of Magnesium Alloys Using Tools with Variable Cutting Edge Geometry

Zagórski Ireneusz

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 2

181--191

EN

This paper presents the results of a study investigating the problem of safety in dry milling magnesium alloy AZ91D. Selected indicators of safe machining were analyzed, including time to ignition, ignition temperature, chip mass and morphology. Experiments were performed using carbide end mills with a variable edge helix angle. It was observed that magnesium alloys could be dry milled without the risk of chip ignition. The milling process conducted with the axial depth of cut ap set to 6 mm was found to be optimum (a great amount of leading fraction A was produced). Unfortunately, however, some machining conditions proved to be inductive to the formation of chip powder known as magnesium dust. For most cases, chips obtained using the tool with λs 50° had higher unit mass than those obtained with λs 20°. Metallographic images of chips confirmed the safe range of the machining parameters employed (no partial melting or burn marks were observed). Determined on a specially designed test stand outside of the machine tool, time to ignition can be an effective parameter for performing simplified chip ignition simulations.

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Comparative Analysis of Peat Fibre Properties and Peat Fibre-Based Knits Flammability

Mikucioniene Daiva, Cepukone Lina, Salmeia Khalifah A., Gaan Sabyasachi

Autex Research Journal

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2019

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Vol. 19, no. 2

157--164

EN

A very promising cellulose-based natural fibre that is suitable for use in the textile industry is peat fibre. This fibre is a by-product of peat excavation, purified by separating it from other components. In this study, the morphological, chemical and mechanical properties of peat fibres as well as flammability of peat-based knitted fabrics were analysed. The average diameter of the peat fibres is ~60 μm, but it varies in very wide ranges – 25–150 μm; however, the number of fibres with diameter more than 100 μm is very low. As the peat fibre contains a high amount of lignin, lignin amount in the mixed peat/cotton yarn is relatively high too. Lignin is responsible for enhanced flame retardancy; therefore, time to ignition of the peat knit is ~30% higher than that of the cotton knit. Consequently, peat fibre can be used in the knitted structure in order to significantly reduce its flammability. In order to increase the flame retardancy, the knits have been treated by flame retardant in various concentrations. It was found that around the burned hole on the peat knit, treated by very low concentration flame retardant, forms charred area and the knit stops to burn even if the flame source is not removed.

3

Study of chip ignition and chip morphology after milling of magnesium alloys

Zagórski I., Kuczmaszewski J.

Advances in Science and Technology. Research Journal

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2016

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Vol. 10, nr 32

101--108

EN

The paper analyses the impact of specified technological parameters of milling (vc , fz, ap ) on time to ignition. Stages leading to chip ignition were analysed. Metallographic images of magnesium chip were presented. No significant difference was observed in time to ignition in different chip fractions. Moreover, the surface of chips was free of products of ignition and signs of strong oxidation.