Effects of Injection Molding Screw Tips on Polymer Mixing

Abstract

In all fields of industry it is important to produce parts with good quality. Injection molded parts usually have to meet strict requirements technically and aesthetically. The aim of the measurements presented in our paper is to investigate the aesthetic appearance, such as surface color homogeneity, of injection molded parts. It depends on several factors, the raw material, the colorants, the injection molding machine and the processing parameters. In this project we investigated the effects of the injection molding machine on surface color homogeneity. We focused on injection molding screw tips and investigated five screw tips with different geometries. We produced flat specimens colored with a masterbatch and investigated color homogeneity. To evaluate the color homogeneity of the specimens, we used digital image analysis software developed by us. After that we measured the plastication rate and the melt temperature of the polymer melt because mixing depends on these factors. Our results showed that the screw tips (dynamic mixers) can improve surface color homogeneity but they cause an increase in melt temperature and a decrease in the plastication rate.

Comparison of Shielding Material Dispersion Characteristics and Shielding Efficiency for Manufacturing Medical X-ray Shielding Barriers

“…There is sufficient space in the injection molding machine screw to mix the materials, permitting mixing at different time intervals. In general, to improve the distribution of metal particles in polymer materials, the speed and residence time of the screw extruder are important [ 28 ]. The dispersion strength ( ; mixing intensity) of the shielding material based on the rate ( ; shear rate) and time ( ; residence time) of the screw extruder during the mixing process can be expressed as follows [ 29 ]: …”

Tailored saturation functions and its application to liquid uptake processes in fibrous composite reinforcements

“…The equation on the right side of equation (8) stands if n = 1/ km and a = c −1/ k providing that the initial asymptote of trues^(x) is s 0 ( x ). In addition, the appropriate choice of exponent m may give a good fitting to the measurements and enables a suitable assessment of S ∞ saturation value.Considering the basic NSF, w ( z ), in different scientific fields, it is often an exponential 1,8 or a hyperbolic 5 function. Since it is well known from the mathematical analysis that there is a convergent hyperbolic function series that tends to an exponential limit function 15 the saturation functions of hyperbolic and exponential types can be treated togetherIt can be noted that the basic NSF may also be a simple logistic function that is often used for describing development or growth processes in biology or economy.…”

“…One of the most frequent saturation processes in polymer materials science and engineering is the liquid uptake of structural materials, such as liquid treatment of polymers and/or resin uptake during impregnating fibres, such as during the manufacture of fibre reinforced polymer composites. 8 In general, some polymers and porous or fibrous materials can uptake liquid or moisture by capillary action through chains of pores, micro-cracks 1,3,4 and/or diffusion of liquid or vapour molecules into their structure. 1,10,11 In practice, it is important to know not only the initial rate of the liquid uptake process but also the degree of saturation at the specified time and the saturation level.…”

Combination of 3D printing and injection molding: Overmolding and overprinting

“…The process is important when several characteristics have to be merged in the same component to increase its functionality. These can be mechanical strength, pleasant touch or a non-slip surface, cushioning against vibration or impact, or esthetic factors [12][13][14][15]. The rigid polymer substrate provides the basic mechanical properties for structural purposes, while the soft polymer cover adds the desired user comfort and product functionalities.…”