Injection molding machines with assistance systems open up new possibilities for even higher process accuracy and product quality. Such intelligent software solutions adjust the process parameters cycle by cycle based on current conditions. One example is iQ weight control by ENGEL, which automatically compensates for external influences such as fluctuations in the raw material. The challenge for medical technology, however, is to integrate this process control into the validation process. Different approaches were examined and a procedure designed which makes it possible to validate processes with iQ weight control in compliance with both EN-ISO and FDA.
For medical products, the regulating groups (also known as Notified Bodies) of the EU and the USA require detailed documentation during the entire product development, process planning and manufacturing process. The requirements can be found in the European standard “EN ISO 13485:2016 – Quality management systems for medical devices” and in the American FDA regulation “21 CFR Part 820 – Quality Systems Regulations”. Both regulations stipulate that a company must validate critical production processes of results that cannot be verified by subsequent monitoring or measurement. This includes injection molding processes in mass production, where 100-percent inline inspection is usually not logical. However, the implementation of the validation is not specified either in the American regulation or in the European standard. Only the tasks to be performed by the manufacturer are recorded in various directives and guidelines.
It is common practice to validate injection molding processes based on machine parameters. However, changing ambient conditions that influence the viscosity of the melt and can lead to rejects are not considered. Many processors are asking themselves how the new process control can be integrated into a validation strategy for the manufacture of medical technology products in compliance with current laws and standards. The key lies in the definition of process windows and the validation of these processes. ENGEL iQ weight control offers the possibility of limiting the scope of modifications. Based on experience or test results, limit values are determined for the adjustable parameters switchover point, injection profile and holding pressure, respectively, and are stored in the control system. This ensures that the process parameters do not fall outside of the validated range despite dynamic process control, and that the process complies with the regulatory requirements.