Internal turning of sintered carbide parts: tool wear and surface roughness evaluation

Made available in DSpace on 2019-09-12T16:53:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2018Universidade de Taubaté (Unitau)Universidade Estadual de Campinas (Unicamp)Universidade Nove de Julho (Uninove)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Turning of sintered carbide parts has not been a common theme in the literature such as the case of other hardened materials. This is a statement made on the basis of recent research on this subject in which journals and conference proceedings were consulted. However, cutting of sintered cemented carbide parts, especially the turning operation, is an important task for a large number of applications where the typical properties of these materials are required. Therefore, the aim of this research was to carry out internal turning experiments in the manufacture of sintered cemented carbide dies used to forge beer cans. The focus of the experiments was to measure and analyze the workpiece surface roughness and wear of cutting edges used in internal turning process. Therefore, samples of sintered cemented carbide WC-Co (12% Co) were submitted to internal turning process with PCD insert tool. Cutting speed and feed rate were used as input variables in the experiments. It was found that, neither very low cutting speeds, nor high feeds can be used to avoid early breakage of the tool. Moreover, for the experiments where no early tool breakage occurred, the increase of feed caused the number of cutting passes prior to the cutting edge breakage to decrease and the workpiece surface roughness to increase. The experiments performed in this work confirm that sintered cemented carbide internal turning, besides being viable, is also feasible to be used to replace grinding operations, at least in terms of surface quality obtained.[Coppini, Nivaldo Lemos] Universidade de Taubaté (Unitau), Rua Daniel Danelli S-N, BR-12060440 Taubate, SP, Brazil[Diniz, Anselmo Eduardo] Univ Estadual Campinas, Sch Mech Engn, BR-13083860 Campinas, SP, Brazil[Lacerda, Felipe Soares; Bonandi, Marcelo; Baptista, Elesandro Antonio] Nove Julho Univ, Rua Vergueiro 235, BR-01504001 Sao Paulo, Brazi

Identification of heart failure hospitalisation from NHS Digital data:comparison with expert adjudication

Background and Aims: Population-wide, person-level, linked electronic health record data are increasingly used to estimate epidemiology, guide resource allocation, and identify events in clinical trials. The accuracy of data from NHS Digital (now part of NHS England) for identifying hospitalisation for heart failure (HHF), a key HF standard, is not clear. This study aimed to evaluate the accuracy of NHS Digital data for identifying HHF.Methods: Patients experiencing at least one HHF, as determined by NHS Digital data, and age and sex matched patients not experiencing HHF, were identified from a prospective cohort study and underwent expert adjudication. Three code sets commonly used to identify HHF were applied to the data and compared with expert adjudication (I50: International Classification of Diseases (ICD)-10 codes beginning I50; OIS: Clinical Commissioning Groups Outcomes Indicator Set; NICOR: National Institute for Cardiovascular Outcomes Research, used as the basis for the National Heart Failure Audit in England and Wales). Results: 504 patients underwent expert adjudication, of which 10 (2%) were adjudicated to have experienced HHF. Specificity was high across all three code sets in the first diagnosis position (I50: 96·2% [95% confidence interval, CI: 94·1 – 97·7%]; NICOR: 93·3% [CI 90·8 – 95·4%]; OIS: 95·6% [CI 93·3 – 97·2%]), but decreased substantially as the number of diagnosis positions expanded. Sensitivity (40·0% [CI 12·2 – 73·8%]) and positive predictive value (PPV) (highest with I50: 17·4% [CI 8·1 – 33·6%]) were low in the first diagnosis position for all coding sets. PPV was higher for the National Heart Failure Audit criteria, albeit modestly (36·4%; [16·6 – 62·2%]).Conclusions: NHS Digital data were not able to accurately identify HHF, and should not be used in isolation for this purpose. <br/

Identification of heart failure hospitalization from NHS Digital data:comparison with expert adjudication

Aims: Population-wide, person-level, linked electronic health record data are increasingly used to estimate epidemiology, guide resource allocation, and identify events in clinical trials. The accuracy of data from NHS Digital (now part of NHS England) for identifying hospitalization for heart failure (HHF), a key HF standard, is not clear. This study aimed to evaluate the accuracy of NHS Digital data for identifying HHF. Methods and results: Patients experiencing at least one HHF, as determined by NHS Digital data, and age- and sex-matched patients not experiencing HHF, were identified from a prospective cohort study and underwent expert adjudication. Three code sets commonly used to identify HHF were applied to the data and compared with expert adjudication (I50: International Classification of Diseases-10 codes beginning I50; OIS: Clinical Commissioning Groups Outcomes Indicator Set; and NICOR: National Institute for Cardiovascular Outcomes Research, used as the basis for the National Heart Failure Audit in England and Wales). Five hundred four patients underwent expert adjudication, of which 10 (2%) were adjudicated to have experienced HHF. Specificity was high across all three code sets in the first diagnosis position {I50: 96.2% [95% confidence interval (CI) 94.1–97.7%]; NICOR: 93.3% [CI 90.8–95.4%]; OIS: 95.6% [CI 93.3–97.2%]} but decreased substantially as the number of diagnosis positions expanded. Sensitivity [40.0% (CI 12.2–73.8%)] and positive predictive value (PPV) [highest with I50: 17.4% (CI 8.1–33.6%)] were low in the first diagnosis position for all coding sets. PPV was higher for the National Heart Failure Audit criteria, albeit modestly [36.4% (CI 16.6–62.2%)]. Conclusions: NHS Digital data were not able to accurately identify HHF and should not be used in isolation for this purpose.</p