Magnesium alloys have been increasingly used in automotive and aerospace components and in portable microelectronic devices due to their “ultralightness” and high specific strength. Machining is an important method used to process magnesium alloys. The advantages of machining over other processing methods such as die casting include reduction in power consumption and excellent surface finish. However, the ignition of chips presents a dangerous problem during machining. This problem has attracted considerable research interests. Though coolants can be used effectively to prevent ignition, the pollution of environment and reclamation of chips can not be resolved easily. Therefore, one better approach is to control the machining parameters for minimizing ignition hazard of magnesium alloy chips during dry machining. A systematic study was conducted for a few different magnesium alloys (including AM50A and AZ91D) to understand effect of cutting parameters (cutting speed, feedrate and depth of cut) on ignition of chips during face milling. It is interesting to find that for any fixed cut depth ignition in the forms of sparks, flares or ring of fire occurs only in the moderate cutting speeds and feedrates and can thus be easily prevented by adopting either higher or lower cutting speeds or feedrates. Chips produced in different machining conditions were collected and their morphology was analyzed to understand mechanisms of ignition.

A method is described to measure temperature on rake face and flank face during high speed milling through the combination of using a non-contact infrared pyrometer and drilling two holes in the workpiece. One of the holes was vertical to the direction of feed for measuring the temperature of rake face, and the other was parallel to the direction of feed for measuring the temperature of flank face. The holes enabled probe beam of the pyrometer to go through them to reach the tool surface directly. The method avoids drilling any hole in the tool and can be used to measure the interface temperature directly. This technique has potential application in monitoring tool temperature and analyzing tool wear during machining of difficult-to-cut materials.

A series of high temperature creep resistant magnesium alloys for die casting based on AZ91 were successfully developed by the addition of Rare Earth, and Calcium. The original target of magnesium alloy development was aimed at cylinder head cover of high power diesel engine, and tried to satisfy the temperature demands of gear-box house. The tensile property at room temperature, creep behavior at 150ı，and analysis of microstructure were discussed in this paper. The results showed that these alloys has potential for die casting to produce power-train parts, and greatly decrease the weigh of parts.