Abstract
Tribological parameters are dependent upon inter alia, inner component properties which may vary with the temperature-time behaviour of the polymer melt used. This temperature-time behaviour can be influenced by dynamic mould temperature control. The present paper presents a new dynamic tempering concept, which enables a targeted temperature-time control via shifting a mould cavity within two different tempered mould areas at a defined point in time. By influencing the temperature-time development by means of a mould temperature and isothermal holding time variation, micro tensile bars with different inner component properties are produced. To show the influence of inner component properties on tribological parameters, pin-on-disc wear tests are performed. Furthermore, tribological tests with different surface topographies are performed to show the influence of topographical properties on tribological parameters. Results indicate that the tribological properties of microparts are mainly influenced by the nature of the skin near layers, which can be influenced by the application of different mould temperatures. Variations in the isothermal holding time show no significant impact on the material examined. A more distinct roughness of the disc surface topography not only shows higher values for the measured tribological parameters but also different wear behaviour in general.
Highlights
Microtechnology has increasingly gained importance in recent years [1]
The production of plastic parts via injection moulding causes high cooling velocities of the polymer melt in the component edges. This influences the development of inner component properties which are mainly dependent on the temperature-time progression of the cooling melt as well as the pressure conditions during production
Several methods for dynamic temperature control are employed in industry
Summary
The demand for microparts is determined by the continuously growing micro electromechanical systems (MEMS) industry [2]. Microparts made of plastic are of particular economic interest because of their comparatively low manufacturing costs and have partially found their application in bio- and medical-technology [3, 4]. The production of plastic parts via injection moulding causes high cooling velocities of the polymer melt in the component edges. This influences the development of inner component properties (e.g., morphology, degree of crystallisation, and orientations) which are mainly dependent on the temperature-time progression of the cooling melt as well as the pressure conditions during production. The maximum nucleation velocity exceeds the growth velocity [5]; see Figure 1
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