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A Cleaner Milling Process Replacing Emulsion Coolant by Cryogenics CO2
Octavio M. Pereira Neto,Calleja‑Ochoa,I. Ayesta,A. Rodríguez,H. González‑Barrio,L. N. López de Lacalle 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.1
In manufacturing sector, looking for a balance between environmental and technical efficiency taking into account productivity is mandatory. Some sectors, such as the biomedical manufacturing sector, also needs to consider the cleanness inherent to prosthesis manufacturing processes for avoiding pathogens transfer to the human body, that is, neither chemicals, bacteria, nor uncontrolled metals can be introduced during the surgical intervention. This work here presented stems from the idea of analyzing the cleanness of cryogenic cooling to be applied to medical pieces. For this, several samples were machined using CO2 cryogenic technology and oil emulsions, respectively. In particular, a modified milling tool was used to apply not only efficiently as cutting fluid but also as cleaner fluid. Afterwards, they were analyzed by Scanning Electron Microscope (SEM) with the aim of looking for biological remains. Finally, with the aim of validating the modified tool in which CO2 is introduced axially as internal coolant, its tool life was tested in comparison with a conventional one. The results shown that the use of CO2 as internal coolant significantly improves the cleanness of current machining processes in comparison with the use of oil emulsions and the way in which is injected does not affect to machining performance.
Simulation of Cryo-cooling to Improve Super Alloys Cutting Tools
Octavio Pereira,Adrián Rodríguez,Amaia Calleja-Ochoa,Ainhoa Celaya,Luis Norberto López de Lacalle,Asier Fernández-Valdivielso,Haizea González 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.1
Improve machining processes from an environmental point of view is a hot topic currently. In this line, cryogenics CO 2 is presented as a solution to substitute conventional oil emulsions. However, to be applied industrially, it is needed to control CO 2 flow rate with the aim of reducing CO 2 consumption to reach what it is known as ECO 2 -performance (economy + ecology). Then, despite currently CO 2 cooling technique is used as external coolant, it is needed to improve its use—especially in milling processes—for achieving this goal. In line with this, in this paper is presented the use of CO 2 as tool internal coolant as a solution to optimize its use. For checking its suitability, a study based on computer fluid dynamics with a new cryogenic tool channels design and experimental tests were carried out for analyzing the differences between using CO 2 as internal and external coolant with the aim of improving the use of cryogenic gases during Inconel 718 milling processes. The results show that the use of CO 2 as internal coolant improves the current milling process not only from environmental point of view but also economic and technical, bringing CO 2 cryogenic technology closer to industrial milling conditions.
Recovery in water polo: how much do we have to know? A systematic review
Josu Barrenetxea-Garcia,Antxon Murua-Ruiz,Juan Mielgo-Ayuso,Sergi Nuell,Julio Calleja-González,Eduardo Sáez de Villarreal 한국운동재활학회 2022 JER Vol.18 No.4
Water polo (WP) is a high-intensity intermittent aquatic sport, with a predominance of swimming skills and nonswimming activities and in-complete recovery periods. Consequently, recovery after exercise is a fundamental part of sports performance. The main purpose of this sys-tematic review was to evaluate the effects of different recovery strate-gies in WP performance. The studies were found by searching in the databases of PubMed, Web of Science, and Scopus. Methodological quality and risk of bias were assessed in accordance with the Cochrane Collaboration Guidelines samples. A summary of results including five studies was followed. The results show that supplementation with cherry juice before training does not imply improvements in recovery; the full-body photobiomodulation therapy reduces muscle damage; re-ducing training load during the season increased the natural logarithm of the root mean square of successive differences and perceived state of recovery, and the heart rate variability stabilizes and could progres-sively increase at the end of a tournament; and when an increase in in-ternal training load is less than 60%–70% autonomic cardiac disturbanc-es during preseason training do not occur. Recovery in WP is a very lim-ited field of study that needs future research in active recovery, hydro-therapy, massage, rest and sleep to help coaches formulate recommen-dations.