Thermocouple and Infrared Sensor-Based Measurement of Temperature Distribution in Metal Cutting

In metal cutting, the magnitude of the temperature at the tool-chip interface is a function of the cutting parameters. This temperature directly affects production; therefore, increased research on the role of cutting temperatures can lead to improved machining operations. In this study, tool temperature was estimated by simultaneous temperature measurement employing both a K-type thermocouple and an infrared radiation (IR) pyrometer to measure the tool-chip interface temperature. Due to the complexity of the machining processes, the integration of different measuring techniques was necessary in order to obtain consistent temperature data. The thermal analysis results were compared via the ANSYS finite element method. Experiments were carried out in dry machining using workpiece material of AISI 4140 alloy steel that was heat treated by an induction process to a hardness of 50 HRC. A PVD TiAlN-TiN-coated WNVG 080404-IC907 carbide insert was used during the turning process. The results showed that with increasing cutting speed, feed rate and depth of cut, the tool temperature increased; the cutting speed was found to be the most effective parameter in assessing the temperature rise. The heat distribution of the cutting tool, tool-chip interface and workpiece provided effective and useful data for the optimization of selected cutting parameters during orthogonal machining

A novel approach to use internally cooled cutting tools in dry metal cutting

239-246This paper presents a new cooling method to be used in dry metal cutting. This new cooling method is based on a tool holder with cooling fluid circulating inside a closed internal cooling system. A prototype that facilitates the cooling from inside the tool holder was specifically designed and manufactured. For this study, a series of cutting trials was carried out to investigate the practicality and effectiveness of the internally cooled cutting tool concept. Two techniques, one using a K-type thermocouple and the second using an infrared (IR) pyrometer, were employed to estimate the temperatures of the tool and the tool-chip interface. Experiments were conducted on DIN 1.2379 cold work die steel (50 HRC) using CVD-coated CNMG 190608-IC907 carbide inserts. The experimental results for dry cutting and for the internally cooled tool were compared using fluid dynamic analysis implemented via the ANSYS Fluent FEA code. The internally cooled tool exhibited the advantages of better surface roughness and extended tool life; in addition, machining was enabled at a wider range of cutting speeds while avoiding environmental hazards and health problems. The results clearly indicated that internal cooling could sufficiently reduce the cutting temperature and consequently, by controlling the critical cutting temperature, was able to circumvent it during the turning process. This technique could generally be advantageous for the machining of hard materials

International Nosocomial Infection Control Consortiu (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module

We report the results of an International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2007-December 2012 in 503 intensive care units (ICUs) in Latin America, Asia, Africa, and Europe. During the 6-year study using the Centers for Disease Control and Prevention's (CDC) U.S. National Healthcare Safety Network (NHSN) definitions for device-associated health care–associated infection (DA-HAI), we collected prospective data from 605,310 patients hospitalized in the INICC's ICUs for an aggregate of 3,338,396 days. Although device utilization in the INICC's ICUs was similar to that reported from ICUs in the U.S. in the CDC's NHSN, rates of device-associated nosocomial infection were higher in the ICUs of the INICC hospitals: the pooled rate of central line–associated bloodstream infection in the INICC's ICUs, 4.9 per 1,000 central line days, is nearly 5-fold higher than the 0.9 per 1,000 central line days reported from comparable U.S. ICUs. The overall rate of ventilator-associated pneumonia was also higher (16.8 vs 1.1 per 1,000 ventilator days) as was the rate of catheter-associated urinary tract infection (5.5 vs 1.3 per 1,000 catheter days). Frequencies of resistance of Pseudomonas isolates to amikacin (42.8% vs 10%) and imipenem (42.4% vs 26.1%) and Klebsiella pneumoniae isolates to ceftazidime (71.2% vs 28.8%) and imipenem (19.6% vs 12.8%) were also higher in the INICC's ICUs compared with the ICUs of the CDC's NHSN