113 research outputs found
Electrohydrodynamic Atomization for Minimum Quantity Lubrication (EHDA-MQL) in End Milling Ti6Al4V Titanium Alloy
No full textTitanium alloy Ti6Al4V is a difficult-to-machine material which is extensively used in the aerospace and medical industries. Machining titanium is associated with a short tool life and low productivity. In this paper, a new cooling-lubrication system based on electrohydrodynamic atomization was designed, manufactured and tested and the relevant theory was developed. The major novelty of the system lies within the use of electrohydrodynamic atomization (EHDA) and a three-electrode setup for generating lubricant droplets. The system was tested and compared with that of flood, minimum quantity lubrication (MQL) and compressed air machining. The proposed system can extend the tool life by 6 and 22 times when compared with MQL and flood cooling, respectively. This is equivalent to more than 170 min tool life at 120 m/min cutting speed allowing for significant productivity gains in machining Ti6Al4V
Investigation of chatter detection with sensor-integrated tool holders based on strain measurement
No full textMachining chatter is one of the most critical issues that restrict the productivity in milling of thin wall workpieces. Sensor-integrated tool/tool holders, which provide data collection during cutting, can be employed for online chatter detection. Recently, there has been an increasing number of strain-measurement-based smart tool holders, which can measure bending moments and/or torque. Although accelerometer-integrated tool holders have been tested, sensor-integrated tool holders based on strain measurement have not been evaluated for the chatter detection in milling. This paper investigates the potential of chatter avoidance using a commercial sensor-integrated tool holder based on strain measurement
Life cycle assessment of cutting tool coatings
No full textThe majority of cutting tools used in industry are coated to improve their performance. Despite this, the environmental impacts of cutting tools and their coatings have been widely overlooked. This paper quantifies the embodied energy and Global Warming Potential (GWP) of cutting tools, with an emphasis on the coating process, by conducting a cradle-to-gate Life Cycle Assessment (LCA). Chemical Vapour Deposition (CVD) and Physical Vapour Deposition (PVD) coating methods have been evaluated, focusing on TiAlN, AlTiN, TiN, AlCrN, and uncoated tool cases. The embodied energy and GWP per unit area for the Cathodic Arc Evaporation PVD case varied between 7.75 – 67.16 Wh/mm2 and 1.56 – 13.55 kgCO₂-eq/mm2, respectively, depending on the coating batch size. The Magnetron Sputter Deposition PVD case recorded the lowest embodied energy of 3.87 Wh/mm2 and GWP of 0.78 kgCO₂-eq/mm2. The CVD deposition showed the highest embodied energy of 11.04 Wh/mm2 and GWP of 2.56 kgCO₂-eq/mm2 for a similar batch size. The analysis indicates that when coating emissions are compared to the carbide tool emissions, the increase in tool life due to coating outweighs the increase in emissions by coating the tool in most cases
Influence of fibre orientation on mechanical behaviour of Onyx-carbon fibre composites fabricated via additive manufacturing
No full textAdditive manufacturing has introduced new possibilities for fabricating composite materials with tailored mechanical properties, particularly through precise control of fibre orientation. This study explores the influence of carbon fibre reinforcement orientation on the mechanical performance of Onyx FR-A composites, manufactured using the Markforged FX20 printer. Mechanical tests, including tensile, compressive, open-hole tension (OHT), and interlaminar shear stress (ILSS) tests, were conducted on specimens with varying fibre orientations (0° and 90° relative to the loading axis). The findings demonstrate that fibre orientation plays a crucial role in determining material behaviour, with 0° orientations providing enhanced tensile and compressive strength compared to 90° orientations. Additionally, additive manufacturing enables the creation of complex geometries, such as OHT specimens, without secondary processes like drilling, which can damage fibres, offering significant advantages over traditional methods. The results offer critical insights into composite design for high-performance applications
Advanced Manufacturing and Machining Processes
No full textManufacturing is one of the major sections of the economy along with services, construction and agriculture [...
A new hybrid Minimum Quantity Lubrication system for machining difficult-to-cut materials
No full textA newly designed and manufactured hybrid MQL system is reported. Vegetable oil and tungsten disulphide suspension are mixed in an additively-manufactured nozzle and delivered through pressurised air as a coolant/lubricant spray. Cooling capability of the system is improved. Lubrication and the impact on machinability is assessed in high speed milling Ti6Al4V. Tool life and cutting forces with the new system are compared to those with air and with flood cooling and with commercial MQL. Over the reported practical range of cutting speeds, tool life is more than 2 times longer than with the commercial system and from 4 to 11 times longer than with air cooling
Inculcate Tehran: Opening a Dialogue of Civilizations in the Shadow of God and the Alborz
No full textThis essay discusses the establishment of Alborz College by American Presbyterian missionaries. Alborz\u27s early years, before its 1940 nationalization by Iran, were shaped by the vision of its first president, Samuel Jordan, a liberal, athletic, pragmatic Christian reformer who led by example, a practitioner of what we now call “social work” and an encourager of female empowerment. Alborz and the Presbyterian mission which gave it birth grew in the context of American social history, including the religious awakening of the early nineteenth century, American doctrines of freedom and universal education, as well as the contradictory impulses of ethnocentricity and ecumenicism. The essay is based on private and governmental archival sources and the experience of the author as a high school student in Tehran.
This history needs to be told.
—Yahya Armajani
All writing is autobiographical.
—Donald Murray
This essay discusses the origins of Alborz College as an effort by private Americans to share with Iran the blessings of their own culture. This they did for decades, cooperating with the Tehran government, without involving Washington. Remarkably, Alborz survived Reza Shah\u27s assault on foreign schools during the 1930s, and it flourished after nationalization as a premier Iranian institution preparing secondary students for modern university studies. It continues as such today
A New Cutting Tool Design for Cryogenic Machining of Ti–6Al–4V Titanium Alloy
No full textTitanium alloys are extensively used in aerospace and medical industries. About 15% of modern civil aircrafts are made from titanium alloys. Ti–6Al–4V, the most used titanium alloy, is widely considered a difficult-to-machine material due to short tool life, poor surface integrity, and low productivity during machining. Cryogenic machining using liquid nitrogen (LN2) has shown promising advantages in increasing tool life and material removal rate whilst improving surface integrity. However, to date, there is no study on cutting tool geometry and its performance relationship in cryogenic machining. This paper presents the first investigation on various cutting tool geometries for cryogenic end milling of Ti–6Al–4V alloy. The investigations revealed that a 14° rake angle and a 10° primary clearance angle are the most suitable geometries for cryogenic machining. The effect of cutting speed on tool life was also studied. The analysis indicated that 110 m/min cutting speed yields the longest tool life of 91 min whilst allowing for up to 83% increased productivity when machining Ti–6Al–4V. Overall the research shows significant impact in machining performance of Ti–6Al–4V with much higher material removal rate
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