Search results1 – 2 of 2
The temperature distribution and history within laser sintered part cakes is an important aspect regarding the process quality and reproducibility of the polymer laser…
The temperature distribution and history within laser sintered part cakes is an important aspect regarding the process quality and reproducibility of the polymer laser sintering process. This paper aims to an analysis of the temperature history during the build and cooling phase, which is decisive for powder ageing effects and the development of part quality characteristics.
A measurement system for three-dimensional in-process temperature measurements is set up and the influence of different parameters on the inner part cake temperature distribution and history is analyzed. In addition, position dependent temperature histories are finally correlated with powder ageing effects.
The main parameters influencing the part cake temperature history are figured out. Temperature inhomogeneities on the powder bed surface are detectable within the part cake, but only for a specific time or additional build height. Heat flux through the build frame results in different cooling rates dependent on z height. A combination of process parameters and build job layout results in individual, position-dependent temperature histories. As a consequence, completely different ageing intensities are found within one part cake.
Temperature measurements are limited to part-free powder cakes so far. To transfer the results to other boundary conditions and machine types, simulation tools have to be developed and validated.
For the first time, the inner part cake temperature distribution and history have been measured during all build phases and with a high sensor density. The results of this work help to understand the temperature history dependency of powder and part properties and can therefore be used to develop optimized process controls.
This paper aims to examine key determinants that influence the decision to outsource facilities management (FM) services. FM is said to be acquiring increasing popularity…
This paper aims to examine key determinants that influence the decision to outsource facilities management (FM) services. FM is said to be acquiring increasing popularity all over the globe, with several sourcing strategies springing up for FM services provision.
Based on questionnaire survey approach, this paper uses purposive sampling to administer 84 questionnaires to selected bank executives operating in the 21 licensed commercial banks in Nigeria, soliciting their responses about what constitute key determinants of outsourcing decision in the context of FM services provision. In all, 41 responses were received, giving a response rate of 49 per cent.
Supported by empirical evidence, this study established 14 factors as key determinants of outsourcing decision for FM services provision. The top three rated factors were “to improve company’s focus”, “to make cost transparent” and “to improve stakeholders’ satisfaction”, while “to restrict own investment in staff”, “to retire personnel” and “to play along with trend in privatisation” were the least rated. There was no significant difference in the rankings of the factors by respondents, while most of the highly rated factors exhibited strong correlation with other factors.
Due to limited dimension of sample size, more robust techniques such as factor analysis and structural equation modelling could not be used.
This paper provides an enhanced understanding of outsourcing decision and basis for further research into decision support models for outsourcing in the context of FM services provision.