Research combines micro gas and projectile injection technology for medical LSRs

The Institute of Plastics Processing (IKV) at RWTH Aachen University, Germany, is investigating the further development of a process for the production of micro-sized hollow articles, such as tubing, made of liquid silicone rubbers (LSR) with integrated functional elements for use in the medical and pharmaceutical industries.

Liquid silicone rubbers (LSRs) are especially suitable for use in medical technology because they open up a wide field of application thanks to their biocompatibility, sterilisability and mechanical and chemical resistance.

In this new approach, IKV is combining the gas and projectile injection technology (GIT and PIT) with the micro-injection moulding of silicone rubbers. It says the use of GIT/PIT should allow such hollow articles to be produced by a free-falling method in a single-step process as well as expecting the development of the micro-GIT/PIT technology to create a more efficient process with the possibility of producing more complex geometries and additional integrated functional elements.

To investigate the processing of LSR with the projectile injection technology in the micrometer range (LSR-μPIT), the research team built a variable test mould for an ultra-small injection moulding machine. Through the use of various inserts, the variable mould technology ensures that outer diameters of 1 - 4 mm can be tested. The injector technology integrated into the standard mould unit with a closable and switchable injector also allows the use of both GIT and PIT with projectile diameters of 0.5 - 3 mm in one system complex of the

mould.

In this project, future work will look at the influence of various process parameters, process variations of the fluid injection technology and different projectile materials with regard to their suitability for the micro injection moulding of silicone. The IKV says the new approach may be an alternative to the production of highly integrated hollow articles that are usually made of thermoplastics. Although thermoplastics are, because of their simple functional integration by welding and the widespread knowledge of the process, broadly used on the global market, researchers say they offer fewer advantages in medical applications.