Case Study: U-Cup Alternative, a Miniature Sealing Solution

miniature sealing solution

The Challenge

A medical equipment manufacturer approached the Marco Rubber & Plastics engineering team to recommend a miniature sealing solution for a very small tube and piston configuration. The space for the seal was a minuscule 0.028-inch cross-section. Furthermore, the seal had to be dynamic with very low friction. Because there was not enough room to design a typical U-cup seal, a different solution had to be found. Lastly, the seal material also had to meet USP Class VI standards, which generally ensure a high-quality level and better acceptance with the FDA and USDA because the materials are believed to substantially reduce the risk of causing harm to patients from reaction to a toxic material.

The Solution

The Marco Rubber engineering team designed a seal that would not only function as the typical U-cup seal but also be easier to manufacture and to install on the miniature piston.

The OD (outside diameter) of the seal was designed to function as a deflection lip seal. However, the ID (inside diameter) was critical and required enough stretch to make it seal, but not too much or it would break during installation. To accomplish the balance between performance and ease of installation, we redesigned the customer hardware to provide for a robust seal retention method while still creating an effective seal around the ID.

The best design means nothing unless it can be manufactured. A complex ID of the seal was not manufacturable due to the lack of space and tool complexity. Therefore, engineering designed a simple square ID that was manufacturable, easy to install and provide an effective seal.

The Result

After manufacturing prototypes, the seals were extensively tested to the full extent of the friction, leakage, and life requirements. The seal performed very well — meeting all the leakage, friction, and life requirements. By developing, engineering, and then testing possible answers for each of the potential issues, an accessible, functional, and effective miniature sealing solution was found.

Contact Marco Rubber today to learn how our engineering expertise can provide effective sealing solutions.