Machinability of Al-20Mg2Si-Cu metal matrix composite modified with bismuth or barium

Aluminum metal matrix composites (MMC) have been receiving growing attention largely owing to their excellent properties, such as excellent castability and mechanical properties. These properties make them useful for high performance applications, especially for lightweight components, particularly in the manufacture of automotive parts. Al-based composite reinforced with particulate Mg2Si phase has recently been shown to possess certain advantages. However, the mechanical properties of normal cast Al-20Mg2Si-Cu metal matrix composite are unsatisfactory due to the natural coarse morphology of the primary Mg2Si phase. Therefore, the melt treatment method with refiner elements was chosen due to improve the morphology of the Mg2Si reinforcement and achieve better mechanical properties. Most of MMC parts require some machining. However, the machinability of Al-20Mg2Si-Cu metal matrix composite is not well understood yet. By adding refiner elements to the composite, the mechanical properties and machinability including particle emissions will be affected. Therefore, the main objective of this thesis is to study the machinability, and mechanical properties of Al-20Mg2Si-Cu metal matrix composite containing bismuth or barium as modifier elements. Results from the different sections of this thesis demonstrate that modifier elements such as bismuth or barium improve the mechanical properties and machinability of the composite. Using modifier elements decreases ultrafine particle emissions during the machining process, which is beneficial for operator health. In addition, the proposed mathematical models for predicting surface roughness and cutting force for this composite are in good agreement with experiment data

Near-dry machining of 319 aluminum-silicon alloy

The use of metal removal fluids reduces friction between the cutting tool and the workpiece material--preventing tool wear and decreasing the adhesion of workpiece materials to the cutting edge. Due to both legal demands and environmental and health concerns, industrial awareness has motivated manufacturers to reduce the volume of their waste streams. A new environmentally friendly technique has been developed that feeds minimal quantities of lubricant to the tool\u27s cutting edge--a method called Minimum Quantity of Lubrication (MQL). This experimental approach was created to help researchers comprehend the cutting performance of uncoated HSS, hydrogenated DLC and non-hydrogenated DLC during the drilling of 319 Al using a minimal quantity of distilled water and triglycerides. Cutting performance is assessed by measuring the torque and thrust forces generated during drilling. The results indicate that improved cutting performance is achieved in torque and thrust force responses when the triglycerides are used

Mechanical properties and machining of aluminum-silicon alloys modified by bismuth or tin

The dry machining performance, microstructure and mechanical properties of hypoeutectic and hypereutectic Al-Si alloys modified with different amounts of Bi and Sn, and cast at different cooling rates, were studied. The measured cutting and thrust forces decreased with the addition of Bi and Sn. These elements caused intense shear localization, and promoted the formation of segmented chips, thereby improving the dry machining performance. Also Bi and Sn melted and thus acted as lubricants during dry turning. However, the mechanical properties decreased with the addition of Sn, although Sn had no effect on the Si morphology. Bi had no effect on the Si morphology when cast at high cooling rates. The optimum amount of Bi addition was found to be 0.5 % and this alloy cast under a high cooling rates of 26 °C/s, improved the overall machining performance without compromising the mechanical properties