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This study aims to obtain diamond-coated mechanical seals with improved sealing performance and considerable cost. To achieve this purpose, the study focuses on depositing…
This study aims to obtain diamond-coated mechanical seals with improved sealing performance and considerable cost. To achieve this purpose, the study focuses on depositing uniform, wear-resistant and easily polished diamond coatings on massive mechanical seals in a large-scale vacuum chamber.
The computational fluid dynamics simulation test and its corresponding deposition experiment are carried out to improve the uniformity of diamond films on massive mechanical seals. The polishing properties and sealing performance of mechanical seals coated with three different diamond films (microcrystalline diamond [MCD], nanocrystalline diamond [NCD] and microcrystalline/nanocrystalline diamond [MNCD]) and uncoated mechanical seals are comparatively studied using the polishing tests and dynamic seal tests to obtain the optimized diamond coating type on the mechanical seals.
The substrate rotation and four gas outlets distribution are helpful for depositing uniform diamond coatings on massive mechanical seals. The MNCD-coated mechanical seal shows the advantages of high polishing efficiency in the initial polishing process and excellent wear resistance and self-lubrication property in the follow-up polishing period because of its unique composite diamond film structures. The MNCD-coated mechanical seal shows the longest working life under dry friction condition, about 14, 1.27 and 1.9 times of that for the uncoated, MCD and NCD coated mechanical seals, respectively.
The effect of substrate rotation and gas outlets distribution on temperature and gas flow field during diamond deposition procedure is simulated. The MNCD-coated mechanical seal exhibits a superior sealing performance compared with the MCD-coated, NCD-coated and uncoated mechanical seals, which is helpful for decreasing the operating system shut-down frequency and saving operating energy consumption.
The purpose of this paper is to examine how knowledge inflows and outflows interact to affect performance outcomes. Though previous studies have dealt with knowledge…
The purpose of this paper is to examine how knowledge inflows and outflows interact to affect performance outcomes. Though previous studies have dealt with knowledge inflows and outflows, the quality and quantity characteristics of knowledge are often not taken into account, thus leaving a research gap with regards to the effect of their interactions on performance outcomes.
Based on Poisson regression analysis, this quantitative study fills the aforementioned research gaps by analyzing the ambidextrous configurations of knowledge flows from an ambidexterity perspective and examines their effects on two-phase performance (i.e. regular season and playoffs), using a longitudinal data set of National Basketball Association transactions from the 2003-2004 to 2014-2015 season.
The results suggest that the complementarity between knowledge inflows and outflows along the quality and quantity dimensions of knowledge, respectively, has a positive impact on two-phase performance, while the imbalance between knowledge inflows and outflows under the quality and quantity dimensions of knowledge, respectively, has a negative impact on playoffs performance (Phase 2). These findings suggest that organizations can balance knowledge inflows and outflows under a single quality or quantity dimension of knowledge. Furthermore, the interaction between the quantity of the inflows of knowledge and the quality of the outflows of knowledge and the interaction between the quality of the inflows of knowledge and the quantity of the outflows of knowledge are both positively related to two-phase performance. These findings suggest that organizations can balance knowledge inflows and outflows across quality and quantity dimensions of knowledge. Finally, the effects of the interaction between knowledge inflows and outflows on playoffs performance are greater than regular-season.
Organizations should leverage ambidexterity to manage/balance knowledge inflows and outflows across quality and quantity dimensions, further enhancing performance outcomes.
This study, first, provides new insights into knowledge flows by distinguishing between the quality and quantity of knowledge, the inflows and outflows of knowledge, constructing ambidextrous configurations of knowledge flows from an ambidexterity perspective. Second, it contributes to the relationship between knowledge flows and organizational performance by revealing how ambidextrous configurations of knowledge flows exert different effects on performance outcomes. Third, it adds to the literature of ambidexterity-performance relationships and expands it to the context of sports.
– The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.
The paper aims to investigate tool wear mechanism and tool geometry optimization of drilling PCB fixture hole.
An experimental study was carried out to investigate the chip formation and tool wear mechanism of drilling PCB fixture holes. Two types of drill with different types of chip-split groove were used in this study. The performances of these two types of drill bots were evaluated by tool wear and the shapes of chips.
The chips of drilling fixture holes contain aluminum chips from the cover board, copper chips from the copper foil, discontinuous glass fiber and resin from the CFRP. Feed rate and drilling speed have a great influence on the chip morphology. Abrasive wear of the drill lip is the main reason of the fixture drill bit in drilling PCB, and micro-chipping is observed on the tool nose and chisel edge. The influence of distance between the chip-split groove and drill point center on the axial force and torque is not obvious.
In this paper, hole wall roughness and drilling temperature were not analyzed in the optimization of drilling parameters. The future research work should consider them.
This paper investigated the mechanism of burr formation and tool wear in drilling of PCB fixture holes. Tool geometry was optimized by adding chip-split grooves.