Büchi Labortechnik AG is a leading global supplier of laboratory technology solutions for research and development, quality assurance and production. Torson Injex AG supplies Büchi with a wide variety of injection molded components and customized multi-component solutions.

The Autodest sensor presented here is used for automatic optimization of distillation parameters and combines several interesting manufacturing technologies in one product.

Requirement: Swiss laboratory quality

The Autodest sensor is used in combination with a Rotavapor® from Büchi in industrial environments for demanding distillation tasks. The sensor determines the optimal distillation parameters and regulates the vacuum according to the measured inlet and return cooling temperatures and the steam temperature.

The Autodest sensor combines three temperature sensors in one product. In the glass tube at the top (No. 1) sits a PT-100 temperature sensor. In addition, there are two PT-1000 sensors, which sit on two stainless steel tubes (No. 2) and determine the flow temperatures of the respective media.

The communication of the sensor is done by a split Mini-DIN 8 pin connector with one male and one female side (No. 3). This can be easily mounted between an existing socket and the associated connector plug.

Implementation:

To ensure an exceptionally high degree of reliability, all components are overmolded in an injection molding process. The glass tube (No. 1) presents a particular challenge. For process-related reasons, glass tubes usually have tolerances in the range of several tenths of a millimeter. This is no different here. In a rigid injection mold, this leads either to the glass tube being crushed and cracking, or to a gap being created into which plastic penetrates and forms an unsightly web.

Torson Injex has developed a special molding technology that allows glass components to be overmolded without cracking and without the formation of a web.

The next challenge arises when overmolding the stainless steel tubes (No. 2) with the soldered-on PT-1000 sensors. These extremely filigree components would not withstand classic injection pressures and would tear off immediately. Therefore, a two-stage low-high pressure process is used here, which first carefully encapsulates the sensitive components and then uses high pressure to mold the desired housing geometry.

The Mini-DIN double connector is another challenge in both injection molding and assembly. The high density of the double-sided 8pin contacts and sockets requires precise soldering and careful, pressure-optimized overmolding. This prevents conductive components from being compressed by excessive pressures and creating a short circuit.

The finished product combines six injection-molded components, 22 electrical contacts, three temperature sensors and a lot of manufacturing know-how in one product: Everything Made-in-Switzerland!