Flexibiltiy, Repeatability, and Ergonomics
Butyl patches are typically installed by hand and can be placed freely on the chassis. This allows greater flexibility with the tradeoff of greater potential variability. Panel plugs have a specific installation location, therefore the provide the opposite: greater repeatability with the tradeoff of less flexibility. It’s a similar story on ergonomics: the better solution will depend on your chassis geometry and assembly line situation. Butyl may be preferred when you have several holes of different shapes and sizes, while panel plugs work very well with a series of holes sharing the same geometry. Lastly, panel plugs are easy to grab from a parts bin while die-cut butyl patches can be peeled from a roll. The better solution will depend on your tact time and assembly line specifics.
In general, butyl patches provide greater NVH damping while panel plugs provide greater sealing and resistance to water swell.
EPDM panel plugs have great temperature resistance as well as great tensile strength and UV resistance.
The answer here is “it depends.” Butyl patches can be die-cut and delivered extremely quickly and have little-to-no tooling costs. Panel plugs require production tooling for high volumes. However, Echo Instant Silicone Prototypes can speed up the process.
Accessible Service Points
For panel holes meant as serviceable areas, the best option of the two will be to go with panel plugs due to their ability to be removed and reinstalled.