The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform
Ann Wennerberg - One of the best experts on this subject based on the ideXlab platform.
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Production Tolerance of conventional and digital workflow in the manufacturing of glass ceramic crowns
Dental Materials, 2019Co-Authors: Deyar Jallal Hadi Mahmood, Michael Braian, Christel Larsson, Ann WennerbergAbstract:Abstract Objectives To measure and compare the size of the cement gap of wax and polymer copings and final glass-ceramic crowns, produced from conventional and digital workflows, one additive and one subtractive. Methods Thirty wax copings were made by conventional manual layering technique and modeling wax on stone models with spacer varnish simulating a cement spacer. The wax copings were embedded and press-cast in lithium disilicate glass ceramic. Thirty wax copings were produced by milling from a wax blank, i.e. subtractive manufacturing, and thirty polymer burn-out copings were produced by stereolithography, i.e. additive manufacturing. These copings were embedded and press-cast in lithium disilicate glass ceramic in the same manner as the conventional group. The fit of the wax/polymer copings and subsequent crowns was checked using an impression replica method. Mean values for cement gap for marginal, axial, and occlusal areas were calculated and differences were analyzed using Student’s t-test. Results There were significant differences in mean values for accuracy/Production Tolerance among different manufacturing techniques for both Production stages: wax and polymer copings and final pressed glass-ceramic crowns. In general, crowns produced from a digital additive workflow showed smaller mean cement gaps than crowns produced from a conventional workflow or a digital subtractive workflow. Additive polymer copings showed significantly smaller cement gaps than milled wax copings (p ≤ .001) and conventional wax copings (p ≤ .001) in the axial area. In the occlusal area, both additive polymer copings and conventional wax copings showed significantly smaller cement gaps than milled wax copings (p = .002 and p ≤ .001 respectively). Crowns produced from conventional manual build-up wax copings showed significantly larger mean cement gaps than crowns produced from milled wax and additively manufactured polymer copings in the marginal and axial areas (p ≤ .001). Among the crowns with smaller cement gaps, crowns produced from additively manufactured polymer copings showed significantly smaller mean cement gaps than crowns produced from milled wax in the marginal and axial areas (p ≤ .001). In the occlusal areas, the differences in mean cement gaps were only statistically significant between crowns produced from conventional manual build-up wax copings and crowns produced from milled wax where the latter ones showed smaller mean cement gaps (p = .025). Significance The present study suggests that an additive manufacturing technique produces smaller mean cement gaps in glass-ceramic crowns than a conventional or subtractive manufacturing technique.
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Production Tolerance of additive manufactured polymeric objects for clinical applications.
Dental materials : official publication of the Academy of Dental Materials, 2016Co-Authors: Michael Braian, Ryo Jimbo, Ann WennerbergAbstract:Abstract Objectives To determine the Production Tolerance of four commercially available additive manufacturing systems. Methods By reverse engineering annex A and B from the ISO_12836;2012, two geometrical figures relevant to dentistry was obtained. Object A specifies the measurement of an inlay-shaped object and B a multi-unit specimen to simulate a four-unit bridge model. The objects were divided into x , y and z measurements, object A was divided into a total of 16 parameters and object B was tested for 12 parameters. The objects were designed digitally and manufactured by professionals in four different additive manufacturing systems; each system produced 10 samples of each objects. Results For object A, three manufacturers presented an accuracy of Significance The growing interest and use of intra-oral digitizing systems stresses the use of computer aided manufacturing of working models. The additive manufacturing techniques has the potential to help us in the digital workflow. Thus, it is important to have knowledge about Production accuracy and Tolerances. This study presents a method to test additive manufacturing units for accuracy and repeatability.
Myoung Ho Sunwoo - One of the best experts on this subject based on the ideXlab platform.
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Influence of MFB50 control on emission dispersions according to engine parameter changes for passenger diesel engines
Applied Thermal Engineering, 2016Co-Authors: Seungsuk Oh, Yungjin Kim, Kihyung Lee, Kyunghan Min, Myoung Ho SunwooAbstract:Combustion phase variations in diesel engines due to Production Tolerance, engine aging, and different combustion conditions cause performance deterioration of fuel economy, torque, and emissions. Therefore, the combustion phase should be controlled by feedback information. A well-known method to control the combustion phase is mass fraction burnt 50% (MFB50) control using in-cylinder pressure. MFB50 control can retain performance through combustion phase compensation despite Production Tolerance, engine aging, and different combustion conditions. However, MFB50 can compensate only for variations caused by combustion phase changes; therefore, further study is required to supplement the limitation of MFB50 control. In this study, to analyze the effect of MFB50 control on combustion, MFB50 is controlled by adjusting the main injection timing using in-cylinder pressure at 1500 rpm and a BMEP of four bar according to engine parameter changes. The parameters are fuel rail pressure, boost pressure, mass air flow, swirl valve open, main injection quantity, pilot injection timing, and quantity. While the engine parameters were changing, the influence of MFB50 control on the combustion and emissions was analyzed to establish improvement points for combustion feedback control. Our experiments demonstrated that MFB50 control reduced NOx dispersions but at the cost of increasing PM dispersions. Therefore, to improve MFB50 control, a control algorithm that can handle PM emission dispersion needs to be considered.
Michael Braian - One of the best experts on this subject based on the ideXlab platform.
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Production Tolerance of conventional and digital workflow in the manufacturing of glass ceramic crowns
Dental Materials, 2019Co-Authors: Deyar Jallal Hadi Mahmood, Michael Braian, Christel Larsson, Ann WennerbergAbstract:Abstract Objectives To measure and compare the size of the cement gap of wax and polymer copings and final glass-ceramic crowns, produced from conventional and digital workflows, one additive and one subtractive. Methods Thirty wax copings were made by conventional manual layering technique and modeling wax on stone models with spacer varnish simulating a cement spacer. The wax copings were embedded and press-cast in lithium disilicate glass ceramic. Thirty wax copings were produced by milling from a wax blank, i.e. subtractive manufacturing, and thirty polymer burn-out copings were produced by stereolithography, i.e. additive manufacturing. These copings were embedded and press-cast in lithium disilicate glass ceramic in the same manner as the conventional group. The fit of the wax/polymer copings and subsequent crowns was checked using an impression replica method. Mean values for cement gap for marginal, axial, and occlusal areas were calculated and differences were analyzed using Student’s t-test. Results There were significant differences in mean values for accuracy/Production Tolerance among different manufacturing techniques for both Production stages: wax and polymer copings and final pressed glass-ceramic crowns. In general, crowns produced from a digital additive workflow showed smaller mean cement gaps than crowns produced from a conventional workflow or a digital subtractive workflow. Additive polymer copings showed significantly smaller cement gaps than milled wax copings (p ≤ .001) and conventional wax copings (p ≤ .001) in the axial area. In the occlusal area, both additive polymer copings and conventional wax copings showed significantly smaller cement gaps than milled wax copings (p = .002 and p ≤ .001 respectively). Crowns produced from conventional manual build-up wax copings showed significantly larger mean cement gaps than crowns produced from milled wax and additively manufactured polymer copings in the marginal and axial areas (p ≤ .001). Among the crowns with smaller cement gaps, crowns produced from additively manufactured polymer copings showed significantly smaller mean cement gaps than crowns produced from milled wax in the marginal and axial areas (p ≤ .001). In the occlusal areas, the differences in mean cement gaps were only statistically significant between crowns produced from conventional manual build-up wax copings and crowns produced from milled wax where the latter ones showed smaller mean cement gaps (p = .025). Significance The present study suggests that an additive manufacturing technique produces smaller mean cement gaps in glass-ceramic crowns than a conventional or subtractive manufacturing technique.
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Production Tolerance of additive manufactured polymeric objects for clinical applications.
Dental materials : official publication of the Academy of Dental Materials, 2016Co-Authors: Michael Braian, Ryo Jimbo, Ann WennerbergAbstract:Abstract Objectives To determine the Production Tolerance of four commercially available additive manufacturing systems. Methods By reverse engineering annex A and B from the ISO_12836;2012, two geometrical figures relevant to dentistry was obtained. Object A specifies the measurement of an inlay-shaped object and B a multi-unit specimen to simulate a four-unit bridge model. The objects were divided into x , y and z measurements, object A was divided into a total of 16 parameters and object B was tested for 12 parameters. The objects were designed digitally and manufactured by professionals in four different additive manufacturing systems; each system produced 10 samples of each objects. Results For object A, three manufacturers presented an accuracy of Significance The growing interest and use of intra-oral digitizing systems stresses the use of computer aided manufacturing of working models. The additive manufacturing techniques has the potential to help us in the digital workflow. Thus, it is important to have knowledge about Production accuracy and Tolerances. This study presents a method to test additive manufacturing units for accuracy and repeatability.
Deyar Jallal Hadi Mahmood - One of the best experts on this subject based on the ideXlab platform.
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Production Tolerance of conventional and digital workflow in the manufacturing of glass ceramic crowns
Dental Materials, 2019Co-Authors: Deyar Jallal Hadi Mahmood, Michael Braian, Christel Larsson, Ann WennerbergAbstract:Abstract Objectives To measure and compare the size of the cement gap of wax and polymer copings and final glass-ceramic crowns, produced from conventional and digital workflows, one additive and one subtractive. Methods Thirty wax copings were made by conventional manual layering technique and modeling wax on stone models with spacer varnish simulating a cement spacer. The wax copings were embedded and press-cast in lithium disilicate glass ceramic. Thirty wax copings were produced by milling from a wax blank, i.e. subtractive manufacturing, and thirty polymer burn-out copings were produced by stereolithography, i.e. additive manufacturing. These copings were embedded and press-cast in lithium disilicate glass ceramic in the same manner as the conventional group. The fit of the wax/polymer copings and subsequent crowns was checked using an impression replica method. Mean values for cement gap for marginal, axial, and occlusal areas were calculated and differences were analyzed using Student’s t-test. Results There were significant differences in mean values for accuracy/Production Tolerance among different manufacturing techniques for both Production stages: wax and polymer copings and final pressed glass-ceramic crowns. In general, crowns produced from a digital additive workflow showed smaller mean cement gaps than crowns produced from a conventional workflow or a digital subtractive workflow. Additive polymer copings showed significantly smaller cement gaps than milled wax copings (p ≤ .001) and conventional wax copings (p ≤ .001) in the axial area. In the occlusal area, both additive polymer copings and conventional wax copings showed significantly smaller cement gaps than milled wax copings (p = .002 and p ≤ .001 respectively). Crowns produced from conventional manual build-up wax copings showed significantly larger mean cement gaps than crowns produced from milled wax and additively manufactured polymer copings in the marginal and axial areas (p ≤ .001). Among the crowns with smaller cement gaps, crowns produced from additively manufactured polymer copings showed significantly smaller mean cement gaps than crowns produced from milled wax in the marginal and axial areas (p ≤ .001). In the occlusal areas, the differences in mean cement gaps were only statistically significant between crowns produced from conventional manual build-up wax copings and crowns produced from milled wax where the latter ones showed smaller mean cement gaps (p = .025). Significance The present study suggests that an additive manufacturing technique produces smaller mean cement gaps in glass-ceramic crowns than a conventional or subtractive manufacturing technique.
Wolfgang Schoch - One of the best experts on this subject based on the ideXlab platform.
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target profile selection Production Tolerance specification for rail grinding considerations towards defining guidelines
Rail Engineering International, 2014Co-Authors: Wolfgang SchochAbstract:An indispensable aspect of track maintenance, rail grinding in Europe has acceptance criteria which have been established with all rail infrastructure managers. A part of various European Committee for Standardization (CEN) norms, there are, however, no specific guidelines currently as to the selection of target profiles or specifications for Production Tolerances to be applied generally. Considerations are presented in this article that have been derived from discussions within the European Rail Maintenance (ERM) Group (which is an informal think-tank formed following the Innotrack project completion). These considerations may contribute towards defining guidelines for Production Tolerance specification and profile selection for track maintenance work of this type.
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Target profile selection & Production Tolerance specification for rail grinding: considerations towards defining guidelines
Rail Engineering International, 2014Co-Authors: Wolfgang SchochAbstract:An indispensable aspect of track maintenance, rail grinding in Europe has acceptance criteria which have been established with all rail infrastructure managers. A part of various European Committee for Standardization (CEN) norms, there are, however, no specific guidelines currently as to the selection of target profiles or specifications for Production Tolerances to be applied generally. Considerations are presented in this article that have been derived from discussions within the European Rail Maintenance (ERM) Group (which is an informal think-tank formed following the Innotrack project completion). These considerations may contribute towards defining guidelines for Production Tolerance specification and profile selection for track maintenance work of this type.
