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Automated Dispensing Improves Processing Stability in Solenoid Valve Production

When manufacturing solenoid valves, clean pins in particular are critical to parts and components during potting processes. If the miniature contacts become contaminated with glue, the electrical conductivity suffers, along with the component quality. Staiger, a producer of solenoid valves and fluidic manifolds, automated the potting of two-component adhesives in magnetic heads for solenoid valves in order to reliably prevent this issue from occurring when manufacturing micro solenoid valves of just 7 mm in size, and to also ensure that exactly the same filling heights are always achieved.

“Up until now, we’ve been mixing the material by hand and then also dosing it into pallets manually,” said Stefan Waldinsperger, the department head for operational and test equipment construction and process development at Staiger. Although the manual potting performed by the four highly trained employees responsible for this process was of an acceptable quality, it nevertheless proved too monotonous to handle for manufacturing quantities of between 600 and 800 units per shift. The increasing difficulties in finding suitably qualified personnel, along with the consistent precision guaranteed by robotics, ultimately drove the decision to automate the process instead.

Initial tests were carried out with a volumetric meter mix dispensing system, eco-DUO from preeflow. Over the course of these tests, it then became clear that the two components of the selected potting compound used were only suitable for static mixing in the eco-DUO under certain conditions. “The two-component material poses challenges for mixing and dosing,” explained Waldinsperger. For this reason, he contacted the provider of microdosing solutions, preeflow. His objective: To discuss alternative technical solutions to the challenge faced by his company. In particular, this concerned the very small design of the solenoid valves and the associated wish to have a precise dosing system that can handle very small quantities. At the same time, the technology needed to be suitable for the challenging material properties of the two-component potting compound. Waldinsperger explained that because the hardener had very low viscosity and because it hardens quickly, even as an individual component, it needed to be processed quickly. These elements impacted the application process.  

Over the course of joint discussions, the parties evaluated the technical requirements and suitable technologies and decided on a two-component dispensing and meter mix system, eco-DUOMIX. The greatest advantage over the system the company tried initially is that the eco-DUOMIX implements the mixing dynamically using a high-torque engine. Particularly for complex media of varying viscosities, this increases the process stability and consequently has an impact on the processing quality.

By chance, preeflow happened to be developing the eco-CONTROL EC200 2.0 control unit in parallel to the Staiger project. As a manufacturer of valves, Staiger also possesses the relevant expertise in control systems to be able to reliably integrate processes into series production. Consequently, the company proved a beneficial consultation partner for the developers of the DUOMIX feature within the new control unit.

ViscoTec subsequently used the feedback from Staiger and modified the new control unit stage by stage. To name just one improvement, it’s now possible to record data even on the operating status of the third engine responsible for the mixing, for example. Staiger employees are now very happy that the manual mixing of the two-component system is now mostly done automatically with the new mixing system. Additionally, because maintenance has been simplified to just filling the tanks with the adhesive material, there is less direct contact by employees, improving the health and safety of process.

Learn more about preeflow and ViscoTec by visiting www.preeflow.com/en.

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