Chip ignition in research on high-speed face milling AM50A magnesium alloy
The ignition of magnesium alloy chips is a problem during high speed dry machining in industry. It should be avoided in the practical production. Many factors including machining environment, material composition, tool geometry, cutting parameters etc. can influence the cutting processes. Among these factors, cutting parameters is one of most important elements to induce the ignition of magnesium alloys. AM50A is a commercial magnesium alloy which is widely used in industry. However, very few reports about the ignition conditions of AM50A magnesium alloy are available. In this paper, we investigated the ignition conditions of AM50A magnesium alloy at different cutting parameters. The relationship between ignition conditions and chip morphologies was further explored. The macro morphologies of the chips were observed by optical microscope and the micro structure were obtained by scanning electron microscope (SEM). It is found that the macro morphologies of chips can be characterized into powdered chip, tubular helical chip, acicular helical chip, and long belt chip, which correspond to the different ignition conditions. The powdered chips and acicular spiral chips are easily ignited. They have thinner lamellar thickness compared to the other two types of chips. These results may be used to analyze cutting process and prevent the chip ignition in dry machining magnesium alloy.
Analysis of chip fragmentation in AZ91HP alloy milling with respect to reducing the risk of chip ignition
The growing demand for tools, vehicles or devices with their weight reduced as much as possible has led to the popularity of magnesium alloys which can be an alternative to other structural materials. From the point of view of machining, magnesium alloys have very good machining properties. They have low specific cutting resistance, low cutting loads and low temperatures in the cutting zone, among others. Magnesium alloys are also characterized by high strength and casting properties, high vibration damping capacity and good electromagnetic radiation shielding [23]. Owing to these properties, magnesium alloys are widely used in such spheres as the automotive industry as well as aircraft and machine design. The growing interest in applications of magnesium alloys in various spheres of life was also generated by advancements in alloy technology and production methods for magnesium products which include, among others, extensive research on special machine tools. Assuming that maintenance is the whole of events and phenomena that occur in a given technical object (from manufacturing to disposal), it is possible to determine safe regions regarding the criterion of reliable and failure-free operation. Given the complexity of machining devices, the assessment of their operational reliability should rather be made in terms of synthesis and analysis of utility, machine reliability and life regarding optimum machining effect and the use ensuring their longest maintenance possible. When it comes to describing state-of-art technological machines (complex cases), it seems advisable to use models with a serial structure, as every machine component must remain usable [13]. The maintenance of certain devices and machines also depends on their structural parameters and their role in a production process. The operational strategy should therefore be tailored to specific devices and machines (Fig. 1) as well as their operational conditions [12].
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.