Scientific Molding

Process

What is Scientific Molding?
It is a methodology for the optimization of the plastic injection process that makes use of techniques organized consistently and supported and documented scientifically; with the purpose of minimizing resources and maximizing the quality of the products. The scientific molding is based on obtaining data during the injection process, which will serve to make decisions, when the piece is being formed; and in a second step, if the pieces continue to have a poor quality, the parameters can be modified to improve the quality of the pieces. The system of molding by Scientific Injection is an ideal method for the optimization of its injection molding process and to acquire a wider and more complete vision of the injection process. The methodology of the scientific molding is applied to obtain stable processes, interpret viscosity curves to find the optimum filling time, learn to perform the sealing graph of the gate to optimize the packing time and determine when a mold is limited by pressure. Optimize the injection molding process using data and thus develop stable processes in your machines. It is a methodology supported by different types of tests and tools that allow analyzing the injection process through tests on the same machine and the definition of parameters of robust processes.
Purpose: Obtain information and recommendations on aspects as relevant as
Adjustment of parameters to have a robust process without rejects Obtaining the viscosity curve Study of the cavity rolling Study of pressure loss Determination of the process window Study of the sealing of the entrance Determination of cooling time Portability between machines Measurement real temperature mold and mass Spindle tip check study to determine if there are problems with the spindle or shut-off valve Study theory nº Reynols to obtain a correct cooling I calculate shears entries to know if the material shears when passing through the injection points Selection of the ideal machine to inject a mold Data record in parameter sheet to ensure repeatability of the injection process
The 6-step study
The viscosity curve (rheology), the study of freezing of doors and the study of pressure drop was a study of scientific mold studies. The molding area diagram (MAD) is the most important and critical step to determine the robustness of the molding process. The balance of fillings in cavities was also identified as an important step. By incorporating this unique umbrella, he coined the term 6 steps study to help optimize the robustness of the process. Below are the 6 steps that should be considered. As always, there are always warnings and exceptions to each of these.
6 phases
Viscosity curve Study of the cavities rolling Study of pressure loss Determination of the process window Study of the sealing of the entrance Determination of cooling time Portability between machines
Drying
First, the material is dried according to the technical date by taking a sample to measure its humidity after the elapsed time. The value must be less than that recommended by the literature that is less than 1000 ppm (0.1%). Once the material is dry, the injection process starts entering the values provided by the technical sheet, and considering an intermediate injection speed in relation to its maximum capacity, the subsequent pressure is considered 75% of the injection pressure and taking Consider the switching point to define the subsequent pressure time.
1 - Generation of the viscosity curve
The viscosity is a more important property in the flow, since it represents the resistance of the material to flow. Viscosity varies, in addition to temperature, with the speed of deformation. The first steps serve to create a viscosity curve that allows to have a relation between the speed of injection and its relation with the apparent viscosity, as an effect of the changes in the speed of injection. The scientific study of the viscosity curve helps to show the effect produced by the injection speed on the viscosity, and also shows the most consistent viscosity region. By monitoring this data, it reduces the variation between the production lots. The idea of "injecting as fast as necessary and not as fast as possible" is directly related to this study, since a slower speed is acceptable if possible. It shows the effect of the injection speed on the viscosity. It shows the most consistent viscosity region. Reduce variation from batch to batch. Caution, it may not be applicable to insert molded components It may not be applicable to optical components Fast injection speeds can cause material degradation and combustion Suggestion, inject as fast as necessary, slower speeds are acceptable
2 - Cavity balance study
This aspect of the process reveals the filling balance between each cavity. It helps in achieving a better consistency between the cavities. It facilitates the study of% imbalance and provides results based on cases. Shows the filling balance between all the cavities. Helps to achieve a better consistency from cavity to cavity Caution, the% imbalance can be very deceptive in smaller parts Suggestion, study the% imbalance with almost full cavities. It does not have an acceptable imbalance limit, for example, 3% or 5% or 10%. It should be case by case
3 - Pressure drop study
This study shows if the process pressure is limited, which can affect the consistency. It is recommended to record the pressure drop through the nozzle and at the end of the filling. Recording the pressure drop in other sections is important only in the case of processes with limited pressure. It shows if the process pressure is limited. Help in consistency Caution, when increasing the pressure, be careful to avoid mold damage. Tip, record the pressure drop through the nozzle and the end of the fill, the rest of the sections are important only if the process is limited by pressure and, therefore, can be eliminated
4 - Proceso estético ventana de estudio
Esto revela la capacidad del molde para formar piezas estéticamente aceptables. Técnicamente, una gran ventana de proceso estético es el primer paso hacia un proceso robusto. Muestra el grado de capacidad del molde para hacer piezas cosméticamente aceptables. Cuanto más grande sea la ventana, mejor son las posibilidades de consistencia. Precaución, al aumentar la presión, tenga cuidado para evitar daños por moho. Presiones más altas pueden causar el sobreembalaje de la pieza. Sugerencia, no use presiones de más de 5000 psi de presión plástica sobre el extremo inferior de la presión aceptable Una gran ventana de proceso cosmético es el primer paso para un proceso robusto
5 - Study of the seal of the door
This shows the action of the door seal. Helps the consistency of shot to shot. However, it is not advisable to conduct a study of sealing the door in a hot channel mold. Also, if the chart does not flatten, it indicates the time for the "Pack and keep" action. Shows when the door is sealed Help in shot-to-shot consistency Caution, do not conduct a door seal study on a hot runner mold With large gate sizes, the graphic can never be flattened, be careful when overpacking the piece With softer materials, such as olefins, the graph can never be flattened Hint, when the graph does not flatten, consider the concept 'Pack and Hold'
6 - Cooling time study
This aspect shows the effect of the cooling time in the production. It also improves cycle efficiency. It is also recommended to perform the study at higher mold temperatures. Shows the effect of cooling time. Improves cycle efficiency. Caution, when molded at lower cooling times, the mold takes longer to reach thermal equilibrium Tip, perform the study at the upper end of the melting temperature or mold. For olefins, set the mold or melt temperatures on the underside and work with the other on the upper side
Scientific Molding
It provides training in scientific injection molding and also provides the tools for all qualifications and molding validations. The use of Scientific Molding has greatly improved the efficiency of molding operations.