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

Energy consumption and carbon footprint analysis of Fused Deposition Modelling: A case study of RP Stratasys Dimension SST FDM.

It is envisaged and expected that professional engineers, process and product developers plays an active role in the sustainable development of manufacturing activities to overcome the global challenges of depletion of natural resources, environmental pollution and damage to the ecosystems. This however calls for the necessity of the industry to adapt and improve on the various manufacturing processes employed for their products not only to keep up with global competition by reducing its variable costs, but also for the sustainable manufacture of their products. Rapid prototyping is one of the new 3D and additive manufacturing technology available globally. This technology has been viewed as a sustainable technology since it optimises electrical energy demand and promotes zero waste technology. This overstretched hypothesis need to be tested. This work evaluate the direct electrical energy demand in fused deposition modelling FDM machine using the Stratasys Dimension SST FDM as a case study and as a panacea to understudy the electrical energy requirement and carbon footprint for rapid prototyping

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

Development of an expert system for the repair and maintenance of bulldozer's work equipment failure

This work aimed to develop an expert fault diagnostic system for the repair and maintenance of bulldozer work equipment faults. An ExpertSystem, ES is one of the many quick and efficient repairs and maintenance strategy that can be used on these machines. ES is a C# computer based programming software that can be adopted to extend the life span of equipments and reduce the cost of human expert for their repairs. In this work, an expert system was developed as a tool that will detect, analyse and proffer respective solutions to the bulldozer work equipment faults. A flowchart (logic chart) was also developed. The flowchart is a logical sequence for characterising and troubleshooting the causes of bulldozer’s work equipment failure. In this report, the solutions to the detected faults: low or high hydraulic valve pressure, abnormal noise in the control valve was documented accordingly. The preferred solutions to the various faults observed were also included with snapshots from each interface of the developed program in the report. The ES developed can be adopted in the construction industries for carrying out repair and maintenance of equipment for optimum performance at a highly reduced cost. This can also be used as a teaching aid in the department of mechanical and mechatronics engineering and other fields of engineering institute. This study will enable automobile and maintenance workshops to proffer solutions to maintenance of bulldozer’s work equipment failure and at the same time avoid costly damage and optimize the economic objective

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

The Impact of 3D Printing Technology to the Nigerian Manufacturing GDP

3D printing can spur manufacturing rebirth in Nigeria and the World in ge n- eral. There are many areas where 3D printing is creating significant change, particularly in designing and prototyping of new products, in the arts, and in visualizing abstract concepts. This is a step change from conventional man u- facturing processes to rapid prototyping and layer manufacturing. This report has defined rapid prototyping, rapid manufacturing and the current technol o- gies available to fabricate 3D components. In addition to this, it provides a brief overview of the current contributions of the Edo University Iyamho (EUI) in collaboration with the Fe deral University of Petroleum Resources, to sustain manufacturing research initiatives towards the development of locally fabricated 3D printer and the possible future Additive Manufacturing in N i- geria. It is anticipated that this work will benefit the Nig erian academic, r e- search institutes, industries, thus, enhance the GDP contribution of the manufacturing sector in Nigeri

Design of a Keypad Operated CNC Drilling Router

The CNC router can be adapted for drilling and engraving operations base d on the imagination and creative skills of the operator. A CNC router consists of three main parts: a mechanical setup that can move in X, Y and Z directions, a driving cir cuitry which includes the stepper motor and a software program that controls the op eration of the system. Although, CNC router is commonly and commercially available, the emphasis is to increase the understanding and encourage developing countries like Ni geria on the developmental process of the CNC router machine. This work presents the development of a CNC drilling router machine using a keypad with the aid of Autodesk 3D Max and Proteus 8 software. The CNC router has a liquid crystal display (LCD) which is l inked to the microcontroller. The program of instructions is written in C progr am compiler. The column strength of the X, Y, and Z axis of the machine were evaluated to be 508.86N, 1142.5N and 7872.64N respectively while the critical speeds of the various axes wer e determined to be 3222, 7234.14 and 49847.78 RPM respectively. The for ces due to the guide rails were evaluated to be 890 N on both the Y and Z axes. This gave a force moment along these axes to be 400.5 and 10.1 kNmm respectively. The stepper motor utilize d for the machine has a 1440 steps/ rev, 500 RPM with 1/8 micro - stepp ing with a phase current of 3.5A and voltage of 2.45V. It is anticipated that the developed machine is able to drill plastics and soft wood materials. The development strategy will aid t he CNC router design concept within the developing economy as Nigeria

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

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe