Chapter 10. Hot Embossing in Science and Industry

This last chapter presents some applications in which hot embossing and related process injection compression molding play an important role for their fabrication. The number of applications increases continually, which makes it impossible to describe all of them. Here, selected examples will be presented to show the manifold of this replication technology. Regarding the different aspects of commercialization, like cost effectiveness and the size of the series of replicated structures, the applications presented here will be split into two different groups. The first group will describe applications that are fabricated in small series or exist only as prototypes. Here, the aim is to show the manifold and the flexibility of this replication process. Because of this development characteristic, these kinds of applications will be classified here in the group of scientific applications. Conversely, large series of parts are commercially replicated by hot embossing and injection compression molding, for example, Fresnel lenses or compact discs. Here, large series, a high grade of automation, and short cycle times are the dominant factors for the cost-effective fabrication of a large number of parts. Compared to the development characteristic, the replication technology for these kinds of applications is typically optimized for cost effectiveness. Therefore, they will be classified here in the group of industrial applications.

Nevertheless, a lot of applications are still in development and may be transferred into mass production.

10.1. Requirements for Hot Embossing in a Scientific Environment and Industry

During development of prototypes, mostly a high grade of flexibility regarding the technology and the set-up of process parameters are in the foreground of interest. The requirements of hot embossing machines in prototype fabrication can be summarized in a compact way:

• a high grade of flexibility regarding the integration and fixation of different kinds of mold inserts
• a variable process control to set up the process to individual requirements. Here, process control by a programming language appears to be the most flexible solution.
• a wide temperature range to allow the molding of different kind of polymers and, further, to allow the characterization of molding windows
• a modular system to allow a comparatively easy adaptation of individual tools and mold inserts
• a measurement system to help analyze the process. It is essential for the further development of the process.

Besides the use of hot embossing in science and prototype fabrication, the process also shows the capability of use in industry for the replication of medium series. Here, the requirements on the hot embossing machines are different. The requirements are mainly oriented toward cost-effective fabrication of molded parts. In the foreground of interest, therefore, is a high grade in automation in combination with short cycle times. Industrial machines do not have the flexibility of laboratory machines; often they are developed and optimized for a certain product. Therefore, a robust system with an efficient process control is desired. Nevertheless, for industrial applications the hot embossing process is, because of the lack of industrial machines, not in as common use as injection compression molding technology. This technology is well developed for large series and optimized for short cycle times. Independent of the technology, the molding cycle, the compression, or the embossing step is similar. Therefore, for industrial use the applications fabricated by injection compression molding can also be taken into account.