DESIGN OF EXPERIMENT (DoE)

Design of Experiment is a method that contains advanced statistical tools, which displays the relationship between the inputs and outputs with mathematical models, especially in the production focused environments. Therefore, it helps us to use a scientific method to calibrate the criterions that are the output of the process to the best levels, instead of using trial and error method or working on just one factor each time. As a consequence of this, the critical parameters of the process can be optimized in the best way.

The best levels of the input parameters that are specified by the Design of Experiment must be continuously controlled by using Statistical Process Control (SPC) methods, and signals that would prevent any mistake before that mistake happens, must be evaluated. However, on the contrary to this approach, in many SPC applications, SPC is applied to critical outputs instead of critical inputs. Regrettably, this error made during the SPC applications, is preventing institutions to reap the benefits of the added value that is expected from SPC. The important point is, controlling the unsteadiness that occurs in the input parameters, and identifying this instability that would manipulate output, before the error occurs (Proactive method).

It is necessary to control the critical process parameters defined pursuant to the Design of Experiment, by using SPC. Additionally, data gathering tables that do not work online, or analyzing the data after it is too late, will not provide any benefit when using SPC applications. With the support of TUBITAK (Scientific and Technological Research Council of Turkey), S.P.A.C. Consultancy developed the software that provides the opportunity to apply SPC systems on an online database. Due to this, data entries concerning the inputs of the production line process can be evaluated online. Moreover, with the help of the signaling mechanism, the e-mails that are sent to the engineers and workers who are responsible for the SPC, attracts their attention to the measurements that cannot pass Nelson tests, and opens the road to Corrective and Preventive Actions. Consequently, the system is providing the opportunity for the correct and healthy application of the SPC tool.