Manufacturing enterprises play an important role in improving the economic environment of a country.Today,the capability to produce high quality products with shorter delivery time and the ability to produce according...Manufacturing enterprises play an important role in improving the economic environment of a country.Today,the capability to produce high quality products with shorter delivery time and the ability to produce according to the diverse customer requirements has become the characteristics of successful manufacturing industries. Application of intelligent manufacturing systems and Computer integrated manufacturing (CIM) are the most effective methods for overcoming the issues faced by present day manufactures while retaining the employment level and revenue of a country in today’s highly competitive global market. With the developments taking place in CIM and its related technologies,the application of CIM in manufacturing enterprises has become a reality from the dream. This paper highlights the historical developments towards automation and the need for CIM systems. Furthermore,it analyses some new terms such as agile manufacturing,digital manufacturing,agent-based manufacturing and others,which have been emerging recently,and argues all these new technologies are the subsystems of CIM. In addition,this paper provides a new direction in CIM to fulfil the emerging challenges in today’s global market and to satisfy the emerging need of virtual enterprises in the form of Virtual CIM.展开更多
It is well-known that grain refiners can tailor the microstructure and enhance the mechanical properties of titanium alloys fabricated by additive manufacturing(AM). However, the intrinsic mechanisms of Ni addition on...It is well-known that grain refiners can tailor the microstructure and enhance the mechanical properties of titanium alloys fabricated by additive manufacturing(AM). However, the intrinsic mechanisms of Ni addition on AM-built Ti–6Al–4V alloy is not well established. This limits its industrial applications. This work systematically investigated the influence of Ni additive on Ti–6Al–4V alloy fabricated by laser aided additive manufacturing(LAAM). The results showed that Ni addition yields three key effects on the microstructural evolution of LAAM-built Ti–6Al–4V alloy.(a) Ni additive remarkably refines the prior-β grains, which is due to the widened solidification range. As the Ni addition increased from 0 to 2.5 wt. %, the major-axis length and aspect ratio of the prior-β grains reduced from over 1500 μm and 7 to 97.7 μm and1.46, respectively.(b) Ni additive can discernibly induce the formation of globular α phase,which is attributed to the enhanced concentration gradient between the β and α phases. This is the driving force of globularization according to the termination mass transfer theory. The aspect ratio of the α laths decreased from 4.14 to 2.79 as the Ni addition increased from 0 to2.5 wt. %.(c) Ni as a well-known β-stabilizer and it can remarkably increase the volume fraction of β phase. Room-temperature tensile results demonstrated an increase in mechanical strength and an almost linearly decreasing elongation with increasing Ni addition. A modified mathematical model was used to quantitatively analyze the strengthening mechanism. It was evident from the results that the α lath phase and the solid solutes contribute the most to the overall yield strength of the LAAM-built Ti–6Al–4V–x Ni alloys in this work. Furthermore, the decrease in elongation with increasing Ni addition is due to the deterioration in deformability of the β phase caused by a large amount of solid-solution Ni atoms. These findings can accelerate the development of additively manufactured titanium alloys.展开更多
文摘Manufacturing enterprises play an important role in improving the economic environment of a country.Today,the capability to produce high quality products with shorter delivery time and the ability to produce according to the diverse customer requirements has become the characteristics of successful manufacturing industries. Application of intelligent manufacturing systems and Computer integrated manufacturing (CIM) are the most effective methods for overcoming the issues faced by present day manufactures while retaining the employment level and revenue of a country in today’s highly competitive global market. With the developments taking place in CIM and its related technologies,the application of CIM in manufacturing enterprises has become a reality from the dream. This paper highlights the historical developments towards automation and the need for CIM systems. Furthermore,it analyses some new terms such as agile manufacturing,digital manufacturing,agent-based manufacturing and others,which have been emerging recently,and argues all these new technologies are the subsystems of CIM. In addition,this paper provides a new direction in CIM to fulfil the emerging challenges in today’s global market and to satisfy the emerging need of virtual enterprises in the form of Virtual CIM.
基金supported by the Agency for Science,Technology and Research(A*Star),Republic of Singapore under the IAF-PP program‘Integrated large format hybrid manufacturing using wire-fed and powder-blown technology for LAAM process’,Grant No.A1893a0031the Academy of Sciences Project of Guangdong Province,Grant No.2016GDASRC-0105。
文摘It is well-known that grain refiners can tailor the microstructure and enhance the mechanical properties of titanium alloys fabricated by additive manufacturing(AM). However, the intrinsic mechanisms of Ni addition on AM-built Ti–6Al–4V alloy is not well established. This limits its industrial applications. This work systematically investigated the influence of Ni additive on Ti–6Al–4V alloy fabricated by laser aided additive manufacturing(LAAM). The results showed that Ni addition yields three key effects on the microstructural evolution of LAAM-built Ti–6Al–4V alloy.(a) Ni additive remarkably refines the prior-β grains, which is due to the widened solidification range. As the Ni addition increased from 0 to 2.5 wt. %, the major-axis length and aspect ratio of the prior-β grains reduced from over 1500 μm and 7 to 97.7 μm and1.46, respectively.(b) Ni additive can discernibly induce the formation of globular α phase,which is attributed to the enhanced concentration gradient between the β and α phases. This is the driving force of globularization according to the termination mass transfer theory. The aspect ratio of the α laths decreased from 4.14 to 2.79 as the Ni addition increased from 0 to2.5 wt. %.(c) Ni as a well-known β-stabilizer and it can remarkably increase the volume fraction of β phase. Room-temperature tensile results demonstrated an increase in mechanical strength and an almost linearly decreasing elongation with increasing Ni addition. A modified mathematical model was used to quantitatively analyze the strengthening mechanism. It was evident from the results that the α lath phase and the solid solutes contribute the most to the overall yield strength of the LAAM-built Ti–6Al–4V–x Ni alloys in this work. Furthermore, the decrease in elongation with increasing Ni addition is due to the deterioration in deformability of the β phase caused by a large amount of solid-solution Ni atoms. These findings can accelerate the development of additively manufactured titanium alloys.
