The miniaturization of manufactured complex micro-components, devices and equipment is increasing significantly. Such emerging needs include tubular micro-components (diameter < 1.0mm), as those used in electrophysiological devices, micro-fluidic-devices and heat-management systems. However, shaping of polymer micro-tubes cannot be achieved simply by scaling down a large scale process and equipment to the micro-scale, due to many size-factors relating to the material, process, tool and machines. To address this issue, specific micro-shaping technologies, which are able to convert small tubes and thin sections into the required functional structures, and corresponding machine systems, have been developed for mass production. The hot-embossing process and the machine are one of the developments within the FP7 POLYTUBES project for the shaping of micro-tubes. Other developments include Laser-Drilling/Trimming, Blow Forming and Cross-Rolling of micro-tubes and the manufacturing platform.
The Hot Embossing Process
Comparing to other processes, hot-embossing has less system-complexity, shorter production cycle-time, lower processing temperature, etc. Nevertheless, the hot embossing process is often used for the moulding on the plain surfaces such as polymeric sheets and thin films or foils, to produce, mostly, 2.5D features. Hot-embossing of polymeric micro-tubes is to form 3D features (both outer and inner features), which requires specific tool-design and process control, including considerations on the stiffness of tubular structures.
Tools and accesories
To enable high-quality hot-embossing of polymeric micro-tubes, tools and coatings are designed and constructed to enable: modular insertion of the core dies; precision guiding of the micro-tube inside the dies; heating and cooling units with a temperature control system; heat-insulation for an improved heating-efficiency; precise alignment of the upper and lower die-sets, etc. The tool design also took the requirement for automated handling into account.