Micro tooling technologies for polymer micro replication: direct, indirect and hybrid process chains

The increasing employment of micro products, of products containing micro parts and of products with micro-structured surfaces calls for mass fabrication technologies based on replication processes. In many cases, a suitable solution is given by the use of polymer micro products, whose production is based on replication technologies such as injection moulding, micro injection moulding, hot embossing, injection compression moulding. Mass fabrication processes pose the highest challenges in terms of the realization of high quality and high performance micro parts, which depend mainly on the quality and performance of the corresponding micro mould. Traditional methods of micro tooling, such as various machining processes (e.g. micro milling, micro electrical discharge machining) have already reached their limitations with decreasing dimensions of mould inserts and cavities. To this respect, tooling process chains based on combination of micro manufacturing processes (defined as hybrid tooling) have been established in order to obtain further features miniaturization and increased accuracy. In this paper, examples and performance of different hybrid tooling approaches as well as challenges, opportunities and comparison between hybrid and direct tooling are presented.