International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The article briefly presents the possibilities of the created and verified model of polymer plasticization during injection molding. Exemplary characteristics generated by the model are presented and examples of applications of the described model for supporting the design of plasticizing systems of injection molding machines are indicated.

The mathematical model of the polymer plasticization in the reciprocating screw injection molding machine is presented. According to the mathematical model, a computer program was developed. Based on the computer program, simulation studies of the injection molding process were conducted. Next, the experimental studies, evaluating the theoretical model from the accuracy and usefulness point of view, were carried out. Important output quantities, such as the temperature and pressure profiles, the power demand by the screw, the torque on the screw and the screw rotation time were measured. The studies were performed on a specially made
research office. The simulation results were compared with the experimental data measured for the most popular polymers and different operating parameters of the injection machine. The experimental studies have indicated the need to introduce some corrections to the mathematical model. Several modifications have been made to the model, related to the methods of stress determining in the polymer layer. Finally, the output characteristics of the plasticization process in the injection molding are now correctly determined by the model with an average error less than 10%.

Injection moulding is a widespread method of polymer processing. The annual, global energy consumption for injection moulding is comparable to the annual energy production of different European countries. The most energy-consuming stage of the injection moulding is the plasticization process, which needs the energy mainly for the rotational and reciprocating screw motion as well as the heating of the barrel. Both issues were examined by changing various parameters of the injection moulding process, measuring the process characteristics and calculating the corresponding values of SEC (specific energy consumption). Various thermoplastic polymers were examined. It was found that the optimal conditions from the energy consumption point of view is low value of rotational velocity of the screw. Changes of back pressure do not affect the energy consumption of the plasticizing system of the injection moulding machine. Furthermore, an increase of the SEC value with increasing barrel temperature was shown. It was ca. 15% for the average barrel temperature rise of 20°C.

Injection moulding is a widespread method of polymer processing. The annual, global energy consumption for injection moulding is comparable to the annual energy production of different European countries. The most energy-consuming stage of the injection moulding is the plasticization process, which needs the energy mainly for the rotational and reciprocating screw motion as well as the heating of the barrel. Both issues were examined by changing various parameters of the injection moulding process, measuring the process characteristics and calculating the corresponding values of SEC (specific energy consumption). Various thermoplastic polymers were examined. It was found that the optimal conditions from the energy consumption point of view is low value of rotational velocity of the screw. Changes of back pressure do not affect the energy consumption of the plasticizing system of the injection moulding machine. Furthermore, an increase of the SEC value with increasing barrel temperature was shown. It was ca. 15% for the average barrel temperature rise of 20°C.

During injection molding of highly filled polymers it is necessary to avoid any inhomogeneities arising from high shear rates/stresses created in molded parts, because they lead to uneven shrinkage after molding, dimensional instabilities and even cracks and voids in the final parts. The testing mold design to intercept so called powder-binder separation has been upgraded to a 3D cube-like model and constructed. Investigation of a tendency to phase separation is however strongly affected by a material and a surface structure of a processing tool. Therefore, flowability of various filled materials in the flow channels designed from different construction materials were tested and compared within this contribution.

This paper covers the advanced Additive Manufacturing (AM) techniques applied to injection mold design and production. Its aim is to do a comprehensive analysis on what AM is doing for the recent and future perspectives in the field of mold’s production.

Further analyses are done on the possible use of Rapid Tooling (RT) techniques based on AM technologies. These include plastic mold inserts made using high strength polymer resins and metal-based technologies for direct tooling work.

Moreover, the work also reviews conformal cooling channel design based on laser sintering AM technologies and its effect in improving mold cooling efficiency to reduce cycle times, which is an important issue in the injection molding process.

Finally, a brief techno-economical analysis is presented, as well as a comparison between the two different types of molds – the conventional ones, and molds produced by rapid tooling. The conclusions leads toward future usage of RT and AM in the mold design and
production.