SPRAY and ROLLER COATING LINES
COMPARISON OF DIFFERENT METHODS OF COATING APPLICATION
Trying to help who wants to have an overlook to the field of the cookware coating, here after we will try to compare the different methods of application of interior and exterior coatings for cookware, to allow to take a decision having clear indication on advantages and features of the different solutions.
CONVENTIONAL SPRAY LINES
The spray application allows to apply all kinds of coatings, on any kind of cookware (press drawn from discs, mould casting, press castings, differentiated thickness cookware, steel cookware, etc.), with the best quality of finishing and the best performances in no-sticking and durability. But the cost of application is relatively high, due to loss of coating material during spraying (up to 50%) and limited production rate (max 2.000 pieces/hour).
PREPARATION OF THE SURFACE:
As far as the application processes are concerned, it is essential to stress the importance of a suitable preparation of the surface to perfectly bond the non-stick /enamel/organic paints.
The best-known technologies are:
· Over smooth system
INTERNAL PTFE or CERAMIC APPLICATION
Automatic lines, completed with booths and drying ovens, provide the application of the requested two or three layers.
The booths can be completed with dry or wet filters and are studied to reduce the quantity of exhausts.
The passage from the spray line to the oven can be manual or completely automatic, in function of different production capacities.
For the external application of porcelain enamel or other kinds of coatings, there is a specific line, where the requested coating is applied. It can be implemented with machineries for the decoration of the bottom.
CURING OF THE APPLIED COATINGS
Thanks to continuous innovations and to the experience cumulated with the furnaces for heat treatment, HTE-NOVAC isable to ensure the highest possible production rate with the lowest possible power consumption. Our belt furnaces are the ideal solution for the curing of the sprayed coatings, since they enable to perfectly follow the typical temperature curve requested by the various manufacturers of PTFE coatings. HTE/NOVAC offers the possibility of programming the different zones of the oven with different temperatures, and thanks to the innovative design of its interior, we are able to supply an optimal system of hot air recirculation.
ROBOTIZED SPRAY LINE
The robotized line has been developed to reduce the intervention of the operators for the setting of the machineries. The robotized line uses an high technology automatic linked transportation system. The system transports the pieces through the various stages of the process. The line is completely automatic, including the system for the spraying of the parts, using robots. The drying sections can be additionally provided with continuous belts ovens and are synchronized with the rest of the transportation system.
This kind of technical solution increases flexibility and efficiency respect the conventional spray lines, thanks to the following facts:
· saving on consumptions for coating (over spray) thanks to the precision of the robots;
· reduction of idle time for the changing of different productions;
· fast and substantial modification of all the spray line parameters thanks to the PC and its control and communication system based on PLC - SCADA program (System Control And Data Acquisition);
· reduction of investments in piece holders and time saving in changing them, according to the various diameters and shapes;
· reduction of operators cost;
that, finally results in a considerable reduction of production costs and in an increasing of constancy in quality.
The robotized line still has a limit in the fact that it cannot produce more than 800 pieces/hour, while the best conventional spray lines can reach a productivity of 2.000 pieces/hour.
ROLLER COATING LINE
The roller coating line has been designed for the application of non-stick coatings and organic paints, suitable for the post-forming process.
The aluminum discs are coated internally and cured, afterwards they are coated and cured externally, and finally sent to the press for drawing and to the finishing line.
HTE/NOVAC can provide lines with production capacity from 2.000 to 12.000 sides per hour.
The production line starts with the pre-treatment of the surface, with one of the following machineries:
· grinding machine
· wet sand brushing machine
· etching - pickling plant
depending on the wishes and needs of the Customer. At the moment, the grinding machine is the most used.
APPLICATION OF THE COATING
The roller coating line is consisting of four or five roller coating machines and starts with a roller table equipped with a synchronization system (line inlet alignment roller table) aligning and pushing the discs in sincronization with the curing furnace.
CURING OF THE APPLIED COATING
The treated discs are moved to the rack furnace (or, alternatively, to a special belt conveyor furnace) by a loading unit and pass through the furnace in a vertical position.
The accurate design and manufacturing of the HTE/NOVAC furnace ensures uniform temperature according to the specifications supplied by the various PTFE suppliers and aiming at the maximum possible power saving and pollution reduced exhausts to the external atmosphere.
The HTE/NOVAC technicians are available to better explain the advantages and disadvantages of the different methods, as per your convenience.