Development of a Novel Pvt Measuring Technique

The pressure-temperature-specific volume relation of polymers is important not only for physical chemistry, but they are very significant input data for injection molding simulation software. Todays methods for measuring pvT data are slow, measurements can take days to be carried out, and in many cases the accuracy of the measurement is unsatisfactory. In our work, a new measuring method has been developed which makes the determination of the pvT relation faster compared to conventional processes within injection molding processing conditions. For the measurements a special injection mould was developed, in which the pvT relation of the material can be determined from the shrinkage in the mold. The data measured by the new method using polypropylene at a mold temperature of 23°C were compared to the data given in the database of the simulation software.</jats:p

Surface Homogeneity of Injection Molded Parts

In this paper we are presenting a novel method for color inhomogeneity evaluation. We proved that this method has a higher than 95 % linear correlation coefficient if results are correlated with human visual evaluations.We applied this evaluation method to analyze the homogenization in the injection molding process, therefore we measured the homogenization properties of various solid phase masterbatches on injection molded parts. We tested the effects of the processing parameters of injection molding and analyzed various dynamic and static mixers as well. We have also measured the influence of the mold surface texture on the sensation of inhomogeneities on the part surface.We have carried out our tests on an injection grade ABS material using various masterbatches. The method was based on the digitization of the molded flat specimens. The images of these specimens were evaluated with an own developed formula using the CIELAB color space resulting high correlation with human visual inspections

INFLUENCE OF MOLD PROPERTIES ON THE QUALITY OF INJECTION MOLDED PARTS

Around one third of all plastics are processed by injection molding, therefore its economy and manufacturing technology have fundamental importance. The major issues in the development of injection molding tools include the progress in material technology and the developments in tool design methodology, such as developing rapid tool inserts. It is essential to develop fast methods to manufacture tools for injection-molded-like prototype parts or mass-produced parts. Due to these high requirements, it is more and more significant to use simulation methods to optimize the part before manufacturing. This paper shows the advantages of tool inserts in injection molding. The main difference between the conventional injection molding tools and rapid tool insert is also described in this paper. Beyond all questions, the rapid tool inserts cause different properties such as different warpage of the polymeric part

Development of Thermally Conductive Polymer Materials and their Investigation

Abstract. In the recent years a remarkable development can be observed in the electronics. New products of electronic industry generate more and more heat. To dissipate this heat, thermally conductive polymers offer new possibilities. The goal of this work was to develop a novel polymer based material, which has a good thermal conduction. The main purpose during the development was that this material can be processed easily with injection molding. To eliminate the weaknesses of the traditional conductive composites low-melting-point alloy was applied as filler. Furthermore in this work the effect of the filler content on thermal conductivity, on structure and on mechanical properties was investigated

Effects of Injection Molding Screw Tips on Polymer Mixing

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

Enhancing Thermal Simulations for Prototype Molds

Our goal was the thermal analysis of epoxy acrylate-based prototype molds with numerical simulations, and to compare and analyze the measured values and calculated results. The difference between the thermal calculations and the measured values is significant; the actual temperature of the mold is higher than the calculated values. Based on the numerical simulations, we found that in the case of epoxy acrylate-based mold inserts, temperature results can be made significantly more accurate by changing the heat transfer coefficient between the surface of the mold insert and the melt. We proved that in the case of small-series epoxy acrylate-based molds, the temperature dependence of the thermal properties of the mold material, and the temperature and pressure dependence of the heat transfer coefficient need to be taken into account for accurate temperature results. We proved that the heat transfer coefficient between the mold surface and the melt is considerably lower than in the case of metal molds, due to lower cavity pressure and a lower temperature difference between the mold surface and the melt

Effect of Processing Parameters and Wall Thickness on the Strength of Injection Molded Products

Polymer materials are getting more and more attention in key industries like the automotive, aerospace, and electrical industries. A long lifetime with sustainable recycling is expected; great results are possible thanks to modern material engineering. Finding a suitable material for the purpose and the appropriate methods to test the required functionality is essential. An important mechanical loading tests is the tensile test. Although the ISO 527-1:2019 standard uses different tensile specimen geometries, none of those consider the possible thickness variations of the injection molded parts. If thickness is reduced to 1 mm, the solid layer will be dominant, which makes the properties of the tensile specimen process-dependent instead of material-dependent. In today's industry, it is crucial to examine both the material and the details of the processing technology together, given the downsizing effect