Cold Spray Coating for Thermoplastic Substrates
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Solution Overview
Problem
Existing methods for applying thermoplastically processable materials to substrate surfaces, such as those used in insulation and coating, face challenges including non-uniform mass distribution, high material costs, and limitations in achieving lightweight construction and targeted acoustic optimization, particularly in vehicle applications, due to inefficiencies in material application and recycling.
Innovation Solution
A method involving the melting of thermoplastically processable materials with an inorganic carrier gas or vapor, expanded through perforated nozzles, and cooled on the substrate surface, allowing for a defined application of materials with or without fillers, enabling the production of homogeneous and uniform coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermoplastics are sprayed using conventional hot spray equipment with melting and liquefaction, then coating application is achieved, but the process has very low throughputs and is conditionally suitable only for temperature-resistant substrates
Solution Approach 1:
The invention changes the fundamental parameters of the spray process by using cold spraying technology instead of conventional hot spray. The thermoplastic material is sprayed in granular or powder form without melting, maintaining ambient or near-ambient temperatures throughout the process. This parameter change enables both high throughput and compatibility with temperature-sensitive substrates like textiles.
Solution Approach 2:
The invention replaces the thermal-mechanical system (melting and liquefaction) with a purely mechanical system. Granular or powder thermoplastic material is accelerated through a nozzle using compressed gas or vacuum pressure, achieving coating deposition through mechanical kinetic energy rather than thermal energy.
2Ease of manufacture
If high temperatures are used during spraying to melt thermoplastics, then coating application is achieved, but the high temperatures would destroy the textile material before anything is applied
Solution Approach 1:
The invention converts the potential harm of high temperatures by eliminating the need for heating altogether. The cold spray process uses the kinetic energy of accelerated particles and the cooling effect of rapid expansion through the nozzle to achieve coating deposition without thermal damage to the substrate.
Solution Approach 2:
The invention fundamentally changes the temperature parameter from high (conventional hot spray) to ambient or near-ambient (cold spray). This parameter change allows coating of temperature-sensitive substrates while maintaining the coating application capability through mechanical acceleration and rapid decompression.
3Manufacturing precision
If injection molding is used to produce components with different defined basis weights, then acoustic optimization is enabled, but the high investment in systems and tools limits these processes to large quantities
Solution Approach 1:
The invention replaces expensive, complex injection molding tools and systems with a simpler, more flexible spray coating system. The coating material is applied in layers that can be controlled in thickness and composition, achieving defined basis weights without requiring costly mold investments. This approach is particularly suitable for low-to-medium production volumes.
Solution Approach 2:
The invention introduces dynamic control of coating parameters (layer thickness, material composition, spray rate) to achieve different basis weights. This dynamic adjustment capability replaces the static mold geometry of injection molding, allowing flexible adaptation to different acoustic requirements without retooling.
4Manufacturing precision
If powder sintering is used to produce flat components, then high-quality components are achieved, but the process is time, tool and energy intensive
Solution Approach 1:
The invention extracts the sintering step from the coating process. Instead of applying powder and then sintering it, the invention sprays already-formed thermoplastic material that deposits and bonds to the substrate without requiring subsequent thermal sintering. This eliminates the time-consuming sintering phase while maintaining coating quality.
Solution Approach 2:
The invention performs preliminary preparation of the coating material by using pre-formed thermoplastic granules or pellets instead of raw powder. The material is sprayed in a state that allows direct deposition and bonding, eliminating the need for post-application sintering that would otherwise be required to consolidate powder coatings.
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 method allows for the efficient and uniform application of thermoplastically processable materials, enhancing material cohesion and reducing material costs, while enabling the production of lightweight, acoustically optimized components with improved recycling potential.
Implementation Method 1
a thermoplastically processable material alone or as a compound in a mixture with other thermoplastically processable materials, with or without fillers, is melted in an extruder with an inorganic carrier gas or vapor under defined pressure
Implementation Method 2
one or more perforated nozzles is pressed as a mixture, expanded to atmospheric pressure and only cooled on the substrate surface
Data Source
AI summary
The invention concerns a method for spray-coating substrate surfaces which enables different thermoplastically processable materials to be applied to very different types of surfaces by means of spray technology.