Redesign of Layout Runner in Rubber Injection Molding for Filling of a Multi-cavity Mold

This study presents a Solidworks� Plastics application in a company in the Automotive Industry for the aftermarket of auto parts manufactured by the injection molding process, the focus is on the redesign of an injection vein plate for achieve uniform filling of a 16 cavity mold with a geometry made up of a mixture of natural rubber and two metal components. This work proves that the use of symmetrical commands is not always the best option. The distances between runners were not taken into account as a source of the future wears problems in the mold. A layout is created with a combination of 2D and 3D sketches by turning the injection chanels 180� in the problem cavities to increase the distances between runners and the filling of the 16 cavities is verified by simulation. It is also demonstrated by simulation that increasing the injection point size is not necessarily always the best option for cavity filling.

Investigation of cavity filling in profile ring rolling process for T-shape ring

In this paper, key parameters affecting the cavity filling in single and double T-shape profile rings are comprehensively investigated via numerical and experimental analysis. A three-dimensional finite element model was developed in Abaqus\Explicit to assess the influence of crucial ring rolling process parameters, including feed speed, main roll rotational velocity, the existence and the absence of axial rolls on the cavity filling of single and T-shape rings and the main roll torque. Besides, a ring rolling machine was built to conduct practical experiments and validate the numerical evaluation, while for the first time, the role of the axial roll and the main roll torque on the quality of the cavity filling is experimentally evaluated. Power requirements and the final ring profile geometry were obtained by the simulation method, and the results were confirmed by the experiments. The results showed that axial rollers significantly reduced the cavity filling rate, and in contrast, the effect of mandrel feed speed and the main roll rotational velocity was much lower. Also, the axial forces were considerably less than the radial forces. However, the rolling operation was done in both radial and axial directions. The existence of axial rolls had an intensive effect on the process’ required power, as a result the main roll torque increased more than three times in case of applying axial rolls, compared with not considering them. Severe effects of axial rollers on increasing force and decreasing cavity filling rate can be attributed to frictional forces between the ring and axial rolls, restricted ring motion, which has to be compensated by a higher torque of the main roll. When the axial rolls are used, the material flow in the ring’s height direction is restricted. Therefore, the material cannot move easily to form the profile. All experimental and simulation results, including mandrel force, cavity filling, and ring profile geometry, were in good agreement, and in all cases, the simulation error was less than 10%.

Guiding Chart for Initial Layer Choice with Nanoimprint Lithography

When nanoimprint serves as a lithography process, it is most attractive for the ability to overcome the typical residual layer remaining without the need for etching. Then, ‘partial cavity filling’ is an efficient strategy to provide a negligible residual layer. However, this strategy requires an adequate choice of the initial layer thickness to work without defects. To promote the application of this strategy we provide a ‘guiding chart’ for initial layer choice. Due to volume conservation of the imprint polymer this guiding chart has to consider the geometric parameters of the stamp, where the polymer fills the cavities only up to a certain height, building a meniscus at its top. Furthermore, defects that may develop during the imprint due to some instability of the polymer within the cavity have to be avoided; with nanoimprint, the main instabilities are caused by van der Waals forces, temperature gradients, and electrostatic fields. Moreover, practical aspects such as a minimum polymer height required for a subsequent etching of the substrate come into play. With periodic stamp structures the guiding chart provided will indicate a window for defect-free processing considering all these limitations. As some of the relevant factors are system-specific, the user has to construct his own guiding chart in praxis, tailor-made to his particular imprint situation. To facilitate this task, all theoretical results required are presented in a graphical form, so that the quantities required can simply be read from these graphs. By means of examples, the implications of the guiding chart with respect to the choice of the initial layer are discussed with typical imprint scenarios, nanoimprint at room temperature, at elevated temperature, and under electrostatic forces. With periodic structures, the guiding chart represents a powerful and straightforward tool to avoid defects in praxis, without in-depth knowledge of the underlying physics.

Prompt gamma imaging for the identification of regional proton range deviations due to anatomic change in a heterogeneous region

Objectives: Prompt gamma (PG) imaging has previously been demonstrated for use in proton range verification of a brain treatment with a homogeneous target region. In this study, the feasibility of PG imaging to detect anatomic change within a heterogeneous region is presented. Methods: A prompt gamma camera recorded several fractions of a patient treatment to the base of skull. An evaluation CT revealed a decrease in sinus cavity filling during the treatment course. Comparison of PG profiles between measurement and simulation was performed to investigate range variations between planned and measured pencil beam spot positions. Results: For one field, an average over range of 3 mm due to the anatomic change could be detected for a subset of spots traversing the sinus cavity region. The two other fields appeared less impacted by the change but predicted range variations could not be detected. These results were partially consistent with the simulations of the evaluation CT. Conclusion: We report the first clinical application of PG imaging that detected some of the expected small regional proton range deviations due to anatomic change in a heterogeneous region. However, several limitations exist with the technology that may limit its sensitivity to detect range deviations in heterogeneous regions. Advances in knowledge: We report on the first detection of range variations due to anatomic change in a heterogeneous region using PGI. The results confirm the feasibility of using PG-based range verification in highly heterogeneous target regions to identify deviations from the treatment plan.

Sound insulation of timber hollow box floors: Collection of laboratory measurement data and trend analysis

The industrialisation of timber buildings has improved strongly in recent years. When long span is required, timber hollow-box floor elements are increasingly used due to their structural performance. The aim of this paper is to assess the acoustic performance of timber hollow-box floors, determine the governing parameters and identify the corresponding trends. We collected results from laboratory measurements covering both airborne and impact sound insulation from four different laboratories covering a wide range of application. Data include the bare floor constructions and their combination with different floating floors including both lightweight solutions and hybrid solution. We performed the analysis focusing on following parameters: element stiffness, element mass per unit area, dynamic stiffness of the resilient layer, cavity filling and floating floor material. We present the collected data both frequency-dependent and as single number quantities. General trends and features are identified in the frequency-dependent diagrams. A further detailed analysis is based on the single number quantities. It includes a general relationship between element mass per unit area and given requirements for R’W + C50-5000 and L’n,w + CI,50-2500. Furthermore, diagrams are presented illustrating the dependence of impact sound insulation numbers on the cavity filling, the dynamic stiffness of the resilient layer and the type of material used for the floating floor. The additional mass in the cavity improves both airborne and impact sound insulation by minimum 10 dB. This, combined with a floating floor, allows the fulfilment of a wide range of requirements.

Filling Ability and Flow of Root Canal Sealers: A Micro-Computed Tomographic Study

This study evaluated by micro-computed tomography (μCT) the filling ability in curved root canals, besides the flow of AH Plus (AHP) and Neo MTA Plus (NMTAP) sealers using different methodologies. Mandibular molars mesial roots with two root canals and degree of curvature between 20° and 40° were selected. The specimens were prepared with the ProDesign R system up to size 35.05 and were filled with the sealers by a continuous wave of condensation technique, Thermo Pack II (n=12). The teeth were scanned using μCT after root canal preparation and obturation. The volumetric percentage of filling material and voids were calculated. Flow was evaluated based on ISO 6876/2012 (n=10). Flow and filling were also evaluated in μCT using a glass plate with a central cavity and four grooves from the central cavity (n=6). Flow was linearly calculated into the grooves. The central cavity filling (CCF) and lateral cavity filling (LCF) were calculated in mm³. Data were submitted to non-paired t test with a significance threshold at 5%. The percentage of filling and voids between the root canals filled with AHP or NMTAP was similar (p>0.05). NMTAP presented the lowest flow in conventional test (p<0.05). Using μCT, sealers had similar CCF, LCF and linear flow (p>0.05). In conclusion, NMTAP and AHP had similar filling ability in curved mesial root canals of mandibular molars without presence of isthmus. Although AHP presented better flow than NMTAP using ISO methodology, there was no difference between these materials regarding volumetric filling when evaluated by μCT.

Titan Nickelide in the Treatment of Dystrophic Bone Cysts in Children

The aim of the study was to assess the efficiency of surgical treatment of patients with dystrophic bone cysts by the method of cyst cavity filling with fine-grain porous titanium nickelide. Methods. The research involved patients with dystrophic bone cysts. 30 patients had an operation of a single-stage opening of the cyst cavity and grafting the residual bone cavity with fine-grain titanium nickelide. Results. The applied treatment method was proven to be effective in the immediate postoperative and long-term periods.Conclusion. Clinical practice demonstrates that the method of dystrophic bone cyst treatment by opening of the cyst cavity with the following grafting with the granules of titanium nickelide gives more positive outcomes compared to the traditional method. This technology allows to reduce the number of post-operational complications and negative outcomes in the long-term perspective.

Investigating the Effect of Counter Gravity Mold Filling on Microstructure and Mechanical Properties of Cast Aluminium

In present study an effort has been made to investigate the effect of changing the mode of mold cavity filling on mechanical properties and microstructure of cast aluminium. The pouring of the melt in mold cavity is avoided so as to check defects associated with it and instead of pouring, counter gravity filling of mold technique is utilized. The obtained properties and microstructure are compared with gravity poured (traditionally cast) aluminium. Characterization techniques like optical microscopy, scanning electron microscopy, X-Ray diffraction and mechanical testing like tensile and hardness of the cast samples is carried out. Hardness and tensile strength reported an increment of 22.37% and 26.71% respectively as compared to traditionally cast specimens. This enhancement in mechanical properties was attributed to improved microstructure obtained.