Micro injection-compression molding

Optical functions in particular are becoming increasingly miniaturized. A well-known example from everyday life is the integrated camera in every modern smartphone. This miniaturization is only made possible by high-precision micro-optics made of plastic. For micro-optics with high image quality, such as for demanding applications in measurement and medical technology, component stresses are often difficult to control. Internal stresses and molecular orientations in injection molded plastic optics cause birefringence effects that lead to unwantes polarization and thus transmission effects. This problem can be eliminated, as in the injection molding of "large" components, by a superimposed injection-compression process. In a partially opened mold, a defined preform is generated within the cavity and then formed into the finished part by means of a compression molding process. Due to the uniform pressure distribution throughout the cavity, internal stresses and thus anisotropic optical properties are reduced to a minimum.

The technological basis for micro injection compression molding of the smallest optical components is the formicaPlast modular machine platform with two piston injection units, which was developed at KUZ for micro injection molding. A vertical machine design with electric drives meets the requirements of the process control necessary for this application. Short cycle times and long flow paths are achieved at low pressure levels.