SCOD Sealant Curing for Aerospace Fastener and Gap Sealing
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Solution Overview
Problem
Current aerospace manufacturing processes are hindered by the time-consuming application and curing of conventional sealing compounds, which require lengthy waiting periods before achieving a tack-free state, leading to increased production times and reduced efficiency, especially when dealing with numerous connection sites on aircraft components.
Innovation Solution
The use of a sulfur-containing SCOD (Sealant Cure on Demand) sealing compound, applied with a nozzle element and irradiated with energy to accelerate curing, allowing for rapid attainment of a tack-free state and Shore A hardness of 30, thereby reducing cycle times and improving reproducibility and quality of the sealing compound coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sealing compounds are used with traditional curing methods, then complete curing and sealing performance are achieved, but production time increases significantly due to lengthy waiting periods before tack-free state
Solution Approach 1:
The sealing compound is applied in advance to the connection elements (bolts, rivets, screws) before final assembly, allowing the sealing material to be positioned and prepared while maintaining its applicability. The compound remains uncured during application and can be adjusted or repositioned if needed, then cured afterward to achieve the seal
Solution Approach 2:
Traditional thermal curing methods are replaced with radiation curing (UV, visible light, or infrared) that initiates polymerization through photoinitiators or other radiation-sensitive components in the sealing compound. This substitution enables rapid curing without prolonged heating, reducing the tack-free time from hours to minutes while maintaining complete curing and sealing performance
2Reliability
If conventional sealing compounds with long curing times are used, then thorough curing is achieved, but manufacturing efficiency and productivity decrease
Solution Approach 1:
The curing process is divided into distinct phases: an initial rapid curing phase triggered by radiation exposure that achieves tack-free state quickly, followed by a secondary phase where curing continues to completion. The sealing compound contains photoinitiators or radiation-sensitive components that activate upon radiation exposure, enabling this staged curing approach that prioritizes speed without sacrificing completeness
Solution Approach 2:
The sealing compound formulation is modified to include photoinitiators, visible-light-sensitive components, or other radiation-responsive additives that enable curing to be triggered and accelerated by electromagnetic radiation. This parameter change in the chemical composition allows the curing process to be controlled and accelerated on demand, transforming it from a slow thermal process to a rapid radiation-initiated process while maintaining thorough curing
3Loss of time
If rapid curing methods are applied to sealing compounds, then production time is reduced, but achieving complete curing and maintaining sealing quality becomes difficult
Solution Approach 1:
The curing process is designed to continue effectively after the initial radiation exposure. The sealing compound formulation ensures that curing is not merely surface-level but progresses through the entire material thickness, maintaining the material in a curing-active state until completion. This continuous curing action ensures that even though the process is rapid, complete curing is achieved throughout the sealing compound, maintaining sealing quality
4Reliability
If traditional sealing compound application processes are used, then adequate sealing is achieved, but the number of processing steps and standby times increases for components with multiple connection sites
Solution Approach 1:
The sealing process is segmented into distinct operational phases: application of uncured sealing compound to connection elements, assembly of components, and then activation of curing by radiation exposure. This segmentation allows the sealing compound to remain in a flexible, adjustable state during application and assembly, then transition to a cured, sealed state afterward, simplifying the overall process for multi-connection components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces production time by 10-50% and enhances the quality and uniformity of sealing compound applications, ensuring faster processing and improved safety by minimizing air traps and leaks, while maintaining high fuel resistance and corrosion protection.
Implementation Method 1
The curing of the SCOD sealing compound is initiated by irradiation with energy, such as UV light
Data Source
AI summary
The invention relates to a method of sealing, coating or/and aerodynamic smoothing of at least one connecting element that protrudes from a surface or/and for sealing, coating or/and aerodynamic smoothing of a surface at a gap or at an uneven connection site with a sulfur-containing SCOD sealing compound at at least one application site, especially on an aerospace component, with at least one nozzle element and with at least one irradiation unit, which is characterized in that i) a nozzle element contains a mixed sealing compound and is guided or/and mounted over the connecting element protruding from a surface, over the gap or/and over the uneven connection site, ii) the connecting element protruding from the surface, the gap or the uneven connection site is covered fully with sealing compound, the sealing compound forming a sealing compound cover essentially in the form of a sealing compound cap, a coating or/and a mound-shaped or bead-shaped elevation, iii) the nozzle element or at least a portion is raised if required from the surface having the sealing compound cover, and iv) the curing of the sealing compound is initiated with the aid of at least one irradiation unit by energy input and by release of a latent catalyst or is brought about by direct activation of at least one reaction component, such that the mixed sealing compound subsequently cures or/and cures further. The invention also relates to a corresponding apparatus, to the aerospace vehicle treated in this way and to the use of the method and the apparatus.