- Automation of seal cap filling thanks to ViscoTec dosing technology.
- Mixing of the sealing material takes place on-demand and ensures significantly less material loss.
- Higher quality and an accelerated process lead to significant cost reductions.
Aircraft such as the Airbus A320 are made from millions of individual parts. Some manufacturing steps in the production process can still only be carried out manually. However, there are now also process steps that are completed fully automatically. The technological leaps of the recent past have made it possible to automate individual process steps that were previously considered “un-automatable” (or at least, unable to be automated in a cost-efficient way). This view was held for a number of different reasons, often budgetary in nature. One of these processes previously considered unsuitable for automation is the filling of seal caps.
These very small caps are used in combination with endless numbers of screw nuts and rivet heads. On components such as tanks, they provide positive connections, and also guarantee leak tightness and corrosion protection in aircraft construction. The company Chemetall manufactures these seal caps in various sizes, using the low-density material MC-780 B from Chemetall itself.
At many locations, the mixing and application of the 2-component sealing material into the seal caps is still carried out manually. This is time-consuming and leads to fluctuations in quality. However, that’s now all set to change: Aerospace companies that use Chemetall seal caps will, in future, also be able to obtain dosing technology from machine manufacturers such as ViscoTec. This technology can be used to mix and dose the sealing material for the seal caps automatically.
The principle is simple: The sealant material is taken from bulk goods and fed to the dosing system. From there, it is dosed directly into the caps. The material which is always provided fresh – combines with the cap during hardening and is made from the same material –. This results in visually impressive, high-quality seal caps with reproducible qualities that could never be achieved with a manual dosing process.
It’s a big leap in development compared to the process that has been used up to now: In the first step, the reactive sealing material had to be mixed with the help of barrier injection cartridges. In these cartridges, the base and hardener are initially separated, then become reactive material once mixed together. This material needed be processed immediately – otherwise, it would quickly become unusable and then had to be disposed of.
With the ViscoTec dosing technology, this mixing is now carried out on demand and in the correct mixing ratio. This is not only an easier process, but one that also significantly reduces material losses, as only the required quantity is mixed. Switching between different seal cap sizes is easy, as the dosing can be adjusted to quantities that have been proven to be precisely reproducible. The material supply for the dosing process is scalable – from the cartridges through to the pails and drums, everything can be adjusted as necessary.
Cooperation between ViscoTec and Bosch Rexroth has also allowed for full automation of the entire seal cap dosing process. For this, aerospace companies procure the Smart Function Kit from Bosch Rexroth and the ViscoTec dosing system separately, then integrate both into their production. Alternatively, integrators offer fully automated cells in which the axis and dosing technology have already been installed.
Both scenarios offer convincing benefits for seal cap filling: The quality is visibly increased, and the process is significantly accelerated. This leads to a significant reduction in costs. The technologies used relieve the burden on individual workers twofold, since no programming knowledge is required: The operator simply has to place the tray in the system. The axis then moves to the different positions of the tray and fills each cap precisely. Once all the caps in the trays have been filled, the Chemetall caps are removed and placed on rivets and screw nuts. For aircraft construction, it’s not an issue if sealing material swells out at the edges of the cap, since this considered a sign of quality. The dosing system is already being employed to great success: ViscoTec very recently implemented a fully automated high-end system together with an integrator, which an aviation company now uses to insert its sealing material into the seal caps.