The project concerns the research and the development of a new solvant-free coating technique, based on thermosetting resin injection.
To achieve this goal, project partners focused on:
- New type of neural based control system. The system integrated correlates inputs from sensors and cameras to overcome current limits, particularly related to thermosetting powder instability.
- New coating process, based on high pressure injection of thermosetting resin and on hot melt hydrodynamic extrusion.
- Specially developed thermosetting compound, controlled in viscosity and polymerisation characteristics.
Through the combination of these three goals, the consortium has introduced a new type of coating machine with a dry operating cycle, that reduces energy consumption compared to solvant painted system.
The consortium has developed a new powder paint, a mechanical system for its direct injection coaxially to the wire and a neural feedback system based on a combination of input data sources such as vision, temperature and pressure. Chemical development of thermosetting resin has focused at first on mechanical properties, then on correct pigmentation and colour brilliance. Since both mechanical injection system and thermosetting coating have to be developed entirely by the consortium, neural data acquisition and fine-tuning process will play a central role in ensuring the optimal working conditions
The core of the innovation concerns the specifics of the application method. The idea is to use a thermosetting powder (which better matches the mechanical requirements compared to thermoplastic resins), to heat it within its thermoplastic range of temperature (a temperature interval, characteristic of every thermosetting powder, which is above the melting point but not high enough to activate the polymerization of the compound), to force it onto the wire using the pressure generated by the hydrodynamic effects of the process and to proceed to the curing in the oven
A precise control of the coating thickness is achieved through a calibrated die and the process is continuous. The goal of a high speed production will be itself the key for the bonding of the coating compound onto the wire, thanks to the hydrodinamic effects generated from the injection.
SPECIFIC INNOVATION RESULTS:
The goal of the High Speed Wire Plant project was to develop a new plant, based on a powder coating technology, which could renovate the process of low diameter steel wires coating. We exhibit the following results:
- Production output = 50 m/min during many hours.
- Good aspect of the final product, but the coating adhesion depends on some parameters that we don’t completely manage. We have identified a dependence on the atmospheric moisture, on the powder aging, on the wire temperature before the contact with the resin and on the cooling system.
- consumption energy = 23 KW at the speed of 50m/min for one wire with the prototype plant but it will be equal for 2 wires.
- No VOC (Volatile Organic Compounds) emissions.
- Real time control of process parameters of speed, pressure and aspect but there was difficulties to know and to set exactly the temperature of the wire.Thermal inertia of the oven is too high to manage temporary phenomena. I believe, we need change the kind of oven to solve all the problem.
- Difficulty to measure wire temperature before the coating and after the curing.
- Need to increase the cooling system, to improve the adhesion of the coating.
At this point of the development, research results are promising, but the plan is still not economically suitable in the industrial area