Bonding and sealing in aircraft production

Metering and mixing system for challenging applications in aerospace industry

Aircraft wings have to withstand very high physical forces.  Because of this, it is important during the production process to fulfill the highest requirements in bonding and sealing applications with 2K polysulfide materials. In addition to efficient filling, special metering and mixing systems require continuous optimisation and state-of-the-art technology. For this process, aircraft manufacturers have been using the volumix from DOPAG for over 25 years. 

One of the most essential parts of an aircraft are the wings. Each component here is particularly important for a safe operation. Accuracy is of enormous importance because the aircraft fuel is stored in the wings. A great precision is important in the bonding and sealing applications, which are mainly manually. Cartridges are used for this purpose. They are filled with two-component materials based on polysulfide at special metering and mixing stations. These systems must be fully inline controlled, providing a precise and reliable volumetric metering and mixing process. In aircraft construction a wide range of different adhesives and sealants are used, which must be precisely metered and mixed. They are necessary to keep the total weight of the aircraft as low as possible. In addition to easy handling, a fully inline controlled, precise volumetric metering and mixing process is therefore required, as well as connectivity to the production line and maximum usability of the material.

volumix – The standard for global aircraft manufacturers
More than 25 years ago aircraft manufacturers start to use DOPAG's specially designed metering and mixing system. Since then the volumix from DOPAG has been continuously enhanced and aircraft manufacturers worldwide have relied on this system for efficient cartridge filling, continuous optimisation and state-of-the-art technology. Accuracy during the metering and mixing process is ensured by the complete separation of the pump and the volumetric metering processes. This means that no internal leakage occurs during the dosing processes. Temperature, pressure, filling level, mixing ratio, flow rates and shot sizes of the mixed material can be accurately read and monitored by the inline flow meter of the volumetric metering technique. "Although our metering pumps are highly accurate, we have developed the volumix with a continuous control of the ratio by the flow meter to avoid any risk in material preparation", explains Elain Montala, Managing Director of DOPAG France.

Easy to operate and resource-saving production
Reliable operation is ensured by a pump per base and hardener side, which is equipped for 200-litre or 20-litre drums. Due to new fillers in the adhesives and sealants, an a pump with servo-electric drive is provided on the base-side. The metering and mixing machine is easy to operate and the electric pump provides constant flow rate. The 2-hand safety button for the pump stations ensures high safety standards. Special requirements also apply to material consumption: For resource-saving production, only a minimum amount of material remains in each used drum. Therefore, cost efficiency and environmental protection are no opposites here.

Independent of the place of use due to cartridges filling
Not all aircraft wing production sites can be equipped with a metering and mixing system. Therefore, the filling of the cartridges is maximally flexible: either they are filled directly on site with the freshly metered and mixed materials, or they are transported frozen to their place of use independently of the location. In the deep-frozen state, the mixing ratio remains constant - both over a long period and during transport. This is an advantage that numerous aircraft factories around the world take advantage of.

In addition to the specific requirements of the aviation industry this technical solution also meet the expectations of many other industries in terms of flexibility, efficiency and sustainability.   

Key features of the volumix metering and mixing system:

  • Mixing station with disposable mixer

  • Electrically adjustable dosing speed
  • Release from 20g up to more than 1kg per shot
  • Multi-cartridge filling system
  • Label printer with shelf life
  • Control unit with colour touch panel including HMI