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On the development of technological properties of ferrite powder
Soviš, Jan ; Dvořák, Jaromír (referee) ; Píška, Miroslav (advisor)
This master’s thesis deals with production of ferrite cores by the powder metallurgy technology in EPCOS s.r.o. Šumperk. Special importance is given to powder compaction process through uniaxial cold pressing in a rigid die. The production company is introduced in the first part and is followed by a study of pressure propagation in a powder bed during uniaxial pressing, then the analysis of critical phases of compaction process in terms of green cracks and compact’s defects follows. Main test methods of compact’s green strength are also presented. Significant part of the master’s thesis deals with an analysis of a powder technological properties’ testing method. For that purpose, an instrumented compaction device called Powder Testing Center (PTC, KZK Powder Tech Corp.) is used. A new pressing tool of smaller diameter was made and mounted to the experimental press; also the testing technique, procedure and certificate of powder’s properties was slightly changed. Technological property called advanced compactibility of powder is introduced. Decision about suitability of powder for uniaxial pressing process is made upon the value of newly introduced coefficient of advanced compactibility . Compact’s green strength is evaluated by a proposed contract bend test method, which uses cylindrical-shaped testing pieces with high height-to-diameter ratio. The results from both testing methods show the impact of additional granulate adjustment on green strength and heterogeneity of density distribution along axial direction. Implementation of gained knowledge to production process led to more than 40 % cost savings in term 2/2016 – 4/2016 in comparison with term 8/2015 – 11/2015, because of lowering the number of scrap parts from KLY material due to crack reduction.
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Influence of uniaxial pressing conditions on final ceramics aimed for ballistic applications
Malý, Martin ; Roleček, Jakub (referee) ; Kachlík, Martin (advisor)
This bachelor thesis is a literary research on the preparation of advanced ceramics with a focus on the uniaxial pressing. The focus is also on the literary review of personal ballistic protection. The experimental part of the thesis was dedicated to the preparation of the Al2O3 ceramics by uniaxial pressing. Relative green density and relative density of sintered samples were measured. The acquired results were discussed in terms of impact of the dimension of the green bodies, pressing pressure and endurance of the pressing pressure. Hardness according to Vickers was measured in a group of chosen samples. The result of the experimental part was successful determination of optimal parameters for the process of uniaxial pressing in terms of relative density and achieved hardness of sintered Al2O3 material. Advanced ceramics prepared this way are suitable for ballistic protection.
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Influence of uniaxial pressing conditions on final ceramics aimed for ballistic applications
Malý, Martin ; Roleček, Jakub (referee) ; Kachlík, Martin (advisor)
This bachelor thesis is a literary research on the preparation of advanced ceramics with a focus on the uniaxial pressing. The focus is also on the literary review of personal ballistic protection. The experimental part of the thesis was dedicated to the preparation of the Al2O3 ceramics by uniaxial pressing. Relative green density and relative density of sintered samples were measured. The acquired results were discussed in terms of impact of the dimension of the green bodies, pressing pressure and endurance of the pressing pressure. Hardness according to Vickers was measured in a group of chosen samples. The result of the experimental part was successful determination of optimal parameters for the process of uniaxial pressing in terms of relative density and achieved hardness of sintered Al2O3 material. Advanced ceramics prepared this way are suitable for ballistic protection.
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On the development of technological properties of ferrite powder
Soviš, Jan ; Dvořák, Jaromír (referee) ; Píška, Miroslav (advisor)
This master’s thesis deals with production of ferrite cores by the powder metallurgy technology in EPCOS s.r.o. Šumperk. Special importance is given to powder compaction process through uniaxial cold pressing in a rigid die. The production company is introduced in the first part and is followed by a study of pressure propagation in a powder bed during uniaxial pressing, then the analysis of critical phases of compaction process in terms of green cracks and compact’s defects follows. Main test methods of compact’s green strength are also presented. Significant part of the master’s thesis deals with an analysis of a powder technological properties’ testing method. For that purpose, an instrumented compaction device called Powder Testing Center (PTC, KZK Powder Tech Corp.) is used. A new pressing tool of smaller diameter was made and mounted to the experimental press; also the testing technique, procedure and certificate of powder’s properties was slightly changed. Technological property called advanced compactibility of powder is introduced. Decision about suitability of powder for uniaxial pressing process is made upon the value of newly introduced coefficient of advanced compactibility . Compact’s green strength is evaluated by a proposed contract bend test method, which uses cylindrical-shaped testing pieces with high height-to-diameter ratio. The results from both testing methods show the impact of additional granulate adjustment on green strength and heterogeneity of density distribution along axial direction. Implementation of gained knowledge to production process led to more than 40 % cost savings in term 2/2016 – 4/2016 in comparison with term 8/2015 – 11/2015, because of lowering the number of scrap parts from KLY material due to crack reduction.
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