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This paper presents the results of mean unit weight of chips and their time to ignition measured on a test stand specially designed for this purpose. In addition, the temperature of chips in the cutting area and the morphology of chips produced in HSM milling (as a temperature indicator in the cutting area) are investigated. Also, different fractions of chips produced in the dry milling of Mg alloys AZ31 and AZ91HP by a PCD end mill are examined. Finally, the paper presents conclusions and recommendations with regard to safety and efficiency of dry milling processes for the aforementioned magnesium alloys.

Milling can be used as a finishing operation, particularly when using PCD end mills. The application of this mill type isparticularly important when producing different machine and device components, especially in the aircraft industry. What can occur in dry machining operations is self-ignition. It is therefore justified to investigate chip temperature in the cutting zone, to classify produced chip fractions and to determine their mass. Safe ranges of technological parameters can be additionally determined based on metallographic analysis of chip edge partial-melting.

The experimental results helped determine the effect of technological parameters of milling on chip temperature in the cutting zone, chip mass and fragmentation and chip morphology images.

The results reported in this work are innovative in both cognitive and practical aspect. The authors are convinced that this work can contribute to overcoming the mistrust of industrial practitioners toward dry milling of Mg alloys, and also with respect to the application of relatively higher cutting speeds in dry milling of these alloys than it is common practice in industry today. The study investigates the problem of safety in dry milling of Mg alloys. The study was motivated by the milling process itself and the formation of broken chip, which causes a significant change in the character of heat transfer.

The paper presents a method for multi-criteria safety assessment in dry milling operations. Safe and effective parameter ranges are defined with respect to chip temperature in the cutting zone, fraction number and chip mass.

The purpose of this paper is to determine time-to-ignition of magnesium alloy chips and the ignition-preceding stages as well as to examine chip morphology. The tests were conducted according to the following pattern: directly after a milling operation, after ignition using a special test stand located outside the machine tool and after intensive oxidation which prevented ignition.

Milling is a machining process widely used in the manufacturing of various parts that are applied, e.g. in the aircraft industry. Milling is used for both roughing and finishing machining. In the dry machining of magnesium alloys, spontaneous ignition can occur; therefore, the analysis of chip temperature in the cutting area is of great significance. Additionally, time-to-ignition and chip morphology are crucial when considering the safety of magnesium alloy machining processes.

The experimental results demonstrate the effect of parameters of the milling process on time-to-ignition of chips made of magnesium alloys AZ31 and AZ91HP. The experiments also involved examining the morphology of a selection of chips produced at the maximum cutting velocity vc and feed per tooth fz. In addition, we analysed the morphology of both ignition products and chips subjected to high temperature where ignition did not occur.

Based on the time-to-ignition and chip morphology results, it is possible to indicate both safety levels in machining and the efficient range of parameters in the milling of aircraft parts made of magnesium alloys.

The paper presents a new approach to assessing safety in milling operations. The results of the tests of chip flammability (time-to-ignition) which were run at a special test stand placed outside the machine tool enabled determination of both safety and efficiency range of the milling process.