Norbert Krisztián Kovács

Developments in the Field of Rapid Prototype Production

Characteristics of 3D printed specimens are porous structure and low mechanical strength. Due to porous structure post treatment is possible, and in most cases infiltration with an epoxy resin, wax or cyanoacrylate material takes place. As a result of post treatment, the mechanical strength can be increased by 100%, although this is strongly influenced by the infiltration depth that depends on the porous structure and the resin viscosity. In the framework of the common research of the Department of Polymer Engineering, BME and Varinex Zrt. the applicability of a 3D printer is examined in the field of direct tool making. As the first step, the resin uptake ability of specimens prepared with a Z810 3D printer is examined.

The Change of the 3D Printing Product Mechanical Properties in the Function of Different Post-Treatment

Rapid prototyping (RP) has changed the method of product design and manufacturing. With the help of RP technologies a physical model can be created within couple of hours from any complex CAD model. RP technologies in contrast with conventional subtractive manufacturing technologies produce the end product by adding material layer-by-layer. 3D printing is one of the most widespread technologies in the industry. Because of the porous structure and bad mechanical properties of the models further post treatment is needed. Post treatment always means infiltration of the models, in case of gypsum and cellulose epoxy resin is mostly used. In our work the effect of post treatment method was examined on the mechanical properties of the pieces. The investigated pieces were prepared with four different setting of a printer.

Enhanced Injection Molding Simulation of Advanced Injection Molds

The most time-consuming phase of the injection molding cycle is cooling. Cooling efficiency can be enhanced with the application of conformal cooling systems or high thermal conductivity copper molds. The conformal cooling channels are placed along the geometry of the injection-molded product, and thus they can extract more heat and heat removal is more uniform than in the case of conventional cooling systems. In the case of copper mold inserts, cooling channels are made by drilling and heat removal is facilitated by the high thermal conductivity coefficient of copper, which is several times that of steel. Designing optimal cooling systems is a complex process; a proper design requires injection molding simulations, but the accuracy of calculations depends on how precise the input parameters and boundary conditions are. In this study, three cooling circuit designs and three mold materials (Ampcoloy 940, 1.2311 (P20) steel, and MS1 steel) were used and compared using numerical methods. The effect of different mold designs and materials on cooling efficiency were examined using calculated and measured results. The simulation model was adjusted to the measurement results by considering the joint gap between the mold inserts.

In vitro and in silico characterization of fibrous scaffolds comprising alternate colistin sulfate-loaded and heat-treated polyvinyl alcohol nanofibrous sheets

A multilayer mat for dispensing colistin sulfate through a body surface was prepared by electrospinning. The fabricated system comprised various polyvinyl alcohol fibrous layers prepared with or without the active ingredient. One of the electrospun layers contained water-soluble colistin sulfate and the other was prepared from the same polymer type and composition without the active drug and was finally heat-treated. The heat treatment modified the supramolecular structure and conferred the polymer nanofibre with the rate-controlling function. The microstructure of different layers was tracked by positron annihilation lifetime spectroscopy, and detailed morphological analysis of the fibre mats was performed using a scanning electron microscope. The drug-release profiles of various layer arrangements were studied in relation to their antimicrobial activity. The finite element method was applied to overcome the challenge of diffusion-controlled drug release from multilayer polymer scaffolds. The finite element method was first verified using analytical solutions for a simple arrangement (one drug-loaded swellable fibre and one rate-controlling nonswellable fibre) under perfect sink conditions and in a well-stirred finite volume. The effect of alternate layer arrangements on the drug-release profiles was also investigated to plan for controlled topical drug release from fibrous scaffolds. This design is expected to aid in increasing local effectiveness, thus reducing the systemic loading and the consequent side effects of colistin.

Rapid Tooling Technologies in the Processing of Thermoplastic Polymers

Thousands of people are affected by the newest achievements of material science and manufacturing technologies each year in the form of biomedical implants. In this field, the aim of developement is to create individual implants to satisfy the geometrical and adapting requirements of the patient. This manufacturing process has been recently improved by shortening the cycle time and using cost effective methods. Biocompatible thermoplastic polymers can be shaped with hot pressing technique. Rapid Tooling was used to create a forming tool for manufacturing process. 3D Printing was used to fabricate the computer generated forming tool. This tool was reinforced by infiltrating it with an epoxy resin. Different epoxy resins were examined to secure the best mechanical properties of this tool. Then the reinforced tool was used for hot pressing of the biocompatible thermoplastic polymer, poly(ε-caprolactone).