Characterisation of the green machinability of AlN powder compacts

Green Al2O3 ceramics through cold isostatic pressing were produced. Scratch tests were performed to evaluate the machinability. Texturing was applied on the flank‐face of the WC/Co tools by laser. Tools with textures on the flank‐face were adopted in dry cylindrical turning of the green Al2O3 ceramics. Characterization of green ceramic surfaces machined by flank‐face textured tools was studied. Results revealed that green ceramics had good enough machinability in cutting tests and scratch tests. There were no visible cracks on the surface after machining. Flank‐face textured tools could improve the surface integrity during processing green Al2O3 ceramics. Mechanisms responsible were found that derivative‐cutting behavior by flank‐face textures was able to remove visible hard inclusions on surfaces of green ceramics, which made the surfaces much smoother. More tiny ceramic powders generated by the phenomenon were pressed on the surfaces of green ceramics, which made further efforts on improving surface quality. Machining parameters had significant impacts on surface integrity. Within machining parameters, surface quality became better and compaction area was found on surfaces of green Al2O3 ceramics with the increase of cutting depth, but there were still visible hard inclusions and spalling of materials on the surface after machining.

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“…Fracture toughness ( K IC ) was measured through 4‐points flexure tests. According to the relation:

K_{normalIC} = μ σ \sqrt{d}

…”

Section: Resultsmentioning

confidence: 99%

Characterization of green Al₂O₃ ceramics surface machined by tools with textures on flank‐face in dry turning

Liu

Deng

Wang

et al. 2019

Int J Applied Ceramic Tech

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“…Para obter um acabamento de alto precisão na usinagem após a sinterização, é necessário utilizar equipamentos específicos, tornando a operação de alto custo, podendo representar até 80% dos valores totais da produção [5].…”

Section: Introductionunclassified

Análise do acabamento superficial e força de corte no torneamento de alumina a verde

et al. 2015

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RESUMOOs esforços de corte durante o torneamento de tarugos de alumina à verde e sua correlação com aspectos superficiais da peça foram estudados em condições experimentais. A correlação entre a força de usinagem e a taxa de remoção de material é um parâmetro importante na definição do projeto de produtos cerâmicos, já que, parâmetros inadequados produzem danos superficiais inaceitáveis na peça. O presente estudo analisou os esforços de corte obtidos durante o torneamento de peças de alumina com 99,8% de pureza no seu estado verde e monitorou a influência da profundidade de corte nestes; utilizando-se ferramentas de corte de cermet sob condições constantes de usinagem. Os esforços de corte foram relacionados com os acabamentos superficiais, desgastes nas ferramentas e temperaturas das ferramentas durante a usinagem. Verificou-se que a profundidade de corte não afetou consideravelmente a qualidade das superfícies. Entretanto, ensaios preliminares para seleção das condições de corte, mostraram que velocidades de corte e avanços inadequados geram danos à superfície da peça. Assim, a melhor condição de corte foi a de maior profundidade de corte, 1,0 mm, uma vez que, com profundidades de corte menores aumenta-se o número de passes necessários para remoção do sobre material da peça, o que inevitavelmente leva a maior desgaste da ferramenta, maior força de usinagem e pior acabamento superficial. Destaca-se que a alumina em seu estado verde apresentou elevado efeito abrasivo sobre a ferramenta durante o torneamento. A sinterização da peça produzida na melhor condição de corte indicou que a qualidade do acabamento na superfície verde foi mantida. Palavra-chave: cerâmica verde, usinagem, forças de corte. ABSTRACTIn experimental conditions, cutting forces were studied during turning of green alumina billets, including their correlation with surface aspects of the workpiece. The correlation between cutting power and the removal rate are important parameters for defining the design of ceramic products, since inadequate parameters can produce excessive surface damage to the workpiece. This study examined the forces obtained during turning of alumina workpieces with 99.8% purity in their green state, by means of a three-point dynamometer, evaluating the cutting, feed and depth forces, using a cermet tool under constant machining conditions. Variables were compared with the forces, including surface finish, tool wear and temperature during machining. In the study, it was found that the depth of cut had no significant effect on the surface quality, and the cutting speed and feed influencing the finish. However, preliminary tests for selecting the cutting conditions showed that unsuitables cutting speeds and feeds generate severe damage to the workpiece surface. The best condition was 1.00 mm depth of cut, and the forces increasedfor with each pass performed, with the feed force the variable with greatest increases in relation to the cutting and depth forces, and wear of the cutting tool directly influenced the surface finish, ge...

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“…Net shape fabrication of ceramics is generally based on powder processing technique 13 . It could be done in two ways, i.e., bottom‐up approach such as direct casting, 14–17 or top‐down approach such as green machining 18,19 . Various bottom up net shape forming processes have been developed, e.g., pressure‐based process such as dry powder pressing, 1,2,10–12 and several well‐established flow‐based processes such as slip casting, 14 extrusion, 10–12 injection molding, 10–12,15–17 etc.…”

Section: Introductionmentioning

confidence: 99%

Green Machining to Net Shape Alumina Ceramics Prepared Using Different Processing Routes

Dhara

2005

Int J Applied Ceramic Tech

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In the present study, the net shape manufacturing of alumina ceramics was carried out using computer numerically controlled (CNC) machining of differently processed alumina green bodies using different tool materials and geometries. In case of a carbide‐coated tool, severe wear was observed; on the contrary, a diamond‐coated tool was used successfully. The profile of the as‐machined surface was found to be smooth using diamond‐coated flat tool. Near net shape alumina was demonstrated using CNC green machining from optimized machining conditions. Optical micrograph and the surface roughness of the as‐machined samples showed good surface finish for the green bodies with higher binder content.

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Characterisation of the green machinability of AlN powder compacts

Cited by 33 publications

References 3 publications

Characterization of green Al₂O₃ ceramics surface machined by tools with textures on flank‐face in dry turning

Characterization of green Al₂O₃ ceramics surface machined by tools with textures on flank‐face in dry turning

Análise do acabamento superficial e força de corte no torneamento de alumina a verde

Green Machining to Net Shape Alumina Ceramics Prepared Using Different Processing Routes

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Characterisation of the green machinability of AlN powder compacts

Cited by 33 publications

References 3 publications

Characterization of green Al2O3 ceramics surface machined by tools with textures on flank‐face in dry turning

Characterization of green Al2O3 ceramics surface machined by tools with textures on flank‐face in dry turning

Análise do acabamento superficial e força de corte no torneamento de alumina a verde

Green Machining to Net Shape Alumina Ceramics Prepared Using Different Processing Routes

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Characterization of green Al₂O₃ ceramics surface machined by tools with textures on flank‐face in dry turning

Characterization of green Al₂O₃ ceramics surface machined by tools with textures on flank‐face in dry turning