Determination of the process variables using the design of experiments for the modelling of the molding by injection of thermoplastics

The more usual for the process is through experimentation, studying the process is doing to study under various combinations of parameters for which the process is affected. The easiest method of experimentation is the modification of a single factor by increasingly carried out the experiment. However, to study complex processes such as injection of thermoplastics in which there are many variables, simple experiments require an excessive time, and also to achieve good results it depends mainly on the ability, experience and intuition of the researcher.

The injection process has the problem that the large number of factors that directly affect the behavior and the outcome of the process are interaccionados each other, which complicates much more research. The classic method of investigation to modify a single factor is no longer valid because the number of experiments carried out would be very high and what does not allow us to study the simultaneous effect of all the factors.

The results of all possible experiments can be treated in a complex process. Varying all factors of the process at various levels are created a large number of results. This collection of results, each is the result of a unique experiment, they can be treated as a mathematical matrix, which means that making only a fraction of all possible experiments allows researchers learn as if those would have made everyone.

The existence of interactions in the process suggests the inconsistency and non reproducibility of conclusions; Therefore, we must try to prevent interactions between the factors of control by all means.

The existence of an interaction depends on the type of measure used in the analysis. In other words, it depends on the selected estimator.

When the process to study is affected by more than a single factor, as in the injection process, design of experiments is used because that allows us to study the simultaneous effect of all the factors. In addition the design of experiments we will detect and quantify us the interactions between two or more factors and as these affect the whole process.

Determination and control of the interaction is the key to getting good results from a process. When the process is very complex, is subject to several factors of control, with interactions and nonlinear effects, the later design of responses of factors can be very complicated. Here is when design of experiments has full power, because it can provide information about the process at a cost and time saving than any other method.

The choice of the appropriate Estimator allows you to define different profiles strategic in the quantification of the process variables depending on the objective (cost, surface quality, dimensions, features mecánicas…).

This article presents the mechanisms used for the determination of the parameters of injection of a blend of ABS-PC using a methodology of experimentation in order to achieve conclusions with the minimum possible number of scenarios.