Optimum Swept Angle Estimation based on the Specific Cutting Energy in Milling AISI 1045 Steel Alloy

Mechanical machining processes are common manufacturing strategies to re-shape materials to desired specification. The mechanistic approach has revealed the mechanics of the machining processes with various parameters determined. The aim of this work is to investigate the impact of swept angle optimization and their influence on the specific cutting energy in milling AISI 1045 steel alloy. This is achieved by varying the step over at different feed rate values in order to determine the optimization criterion for machining. It was observed that an optimum swept angle of 31.8 o was appropriate in the elimination of ploughing effect and reducing the specific cutting energy to an optimised minimum value. However, higher swept angle of 41.4 o increases the specific cutting energy with a higher machine tool power. This is attributable to the reduction in the cycle time caused by shorter toolpath length. The results obtained further elucidate the knowledge base for the determinations of optimum parameters for sustainable machining and resource efficiency of manufactured products

The effect of Auxiliary Units on the Power Consumption of CNC Machine tools at zero load cutting

Electricity consumptions have attracted global interest in recent times. This is attributable to the increasing technological advancement and new machines and materials development hence, an urgent global call for energy efficiency and sustainable manufacture. The electricity consumption in the manufacturing sector especially at the process level stages is an increasing trend. This is partly due to the energy demand of the auxiliary units and machine features incorporated into the machine tools at the design and manufacturing stages and on the other, as a result of increased production activities (increased product demand) during the use phase. This resulted in an increased embodied product energy that affects the cost and life cycle assessment of the product. In view of this economic and environmental objectives, it is paramount to investigate the energy consuming activities during machining (i.e. tip energy and zero load cutting energy) in order to optimize electricity demand at the secondary processing stages. In this work, the electrical energy demand of the auxiliary units and machine features of three different machine tools were investigated and characterized. This is required in order to encourage symbiotic and sustainable manufacture of products for resource optimization and also to determine specific areas for energy savings. It was observed that the electrical energy demand for non-cutting activities dominate the machining processes at more than 70% and the zero load cutting energy, which is machine dependent, is also about 14%. A step change in axes motor designs for CNC machine tools could facilitate energy reduction in this direction

Specific energy based characterization of tool wear in mechanical machining processes

The global trend for energy consumption as a foundational requirement for economic and social development is an increasing one. Electricity consumption is proportional to the CO2 emitted at the process level and especially for machining processes. The electrical energy demand during machining can be categorized and modelled as basic energy (energy demand by the machine tool while operating at zero load) and tip energy (energy for actual material removal – cutting). The tool tip energy is evaluated from the specific cutting energy. At present limited data exists with regards to the key parameters required for modelling the tip energy. Previous studies and data for specific energy were based on the normalisation of the total energy demand with the material removal rate and have not investigated the effect of tool wear. In this work, the impact of tool wear on the specific energy coefficients in machining were studied and modelled. Cutting tests were performed and tool wear and tool life based on the specific energy coefficient for each wear land value were evaluated. The study has for the first time provided data on the variation of specific cutting energy for higher tool wear lands and presents vital sensitivity analysis. With longer cutting time, tool wear increases which leads to higher specific cutting energy and energy consumption during machining. The specific energy coefficient increased by up to 50% when turning EN8 steel alloy between 2 and 10 passes. This knowledge is vital information for process planners and could enable energy estimates to be more accurate and realistic with regards to capturing the impact of tool wear

Effect of Cutting Parameters on Surface Finish when Turning Nitronic 33 Steel alloy

Nitronic 33 steel alloys are metallic alloys that exhibit characteristics such as high strength-to-weight ratio, outstanding corrosion and erosion resistant properties, and the ability to withstand cryogenic conditions and elevated temperatures. These characteristics of Nitronic 33 steel alloys make it popular in the fabrication of chemical processing, pollution control, aerospace equipment, and for steam and autoclave applications. Nitronic 33 steel alloy is classified as difficult-to-cut materials because of its high nitrogen content and the capability to form martensite as a result of high temperatures generated during mechanical machining and other subtractive manufacturing processes. This resulted in increased capacity and tooling cost during manufacturing. Therefore, there is the need to evaluate the optimum parameters when machining this alloy for sustainable and resource efficient machining. In this work, tool life, tool wear, surface roughness, cutting forces and power demand when turning Nitronic 33 steel alloy under different cutting environment were investigated. The result presented an optimum turning conditions at which Nitronic 33 steel alloy can be manufactured with minimum tool wear and surface integrity. The research outcome also addresses some of the problems encountered during the high speed machining of Nitronic 33 steel alloy that could influence manufacturing cost reduction. This work will also aid the general understanding of Nitronic 33 steel alloy with respect to sustainable and resource efficient machining