Powder coating

Powder coating is performed in the only power coating shop in Poland, in which aluminum profiles are hanged and transported vertically.

The technical level of the equipment and technologies used in the company are the most advanced in the power coating branch.

The major features that make this line different from other existing appliances are its enormous output and power coating quality.

The line allows power coating vprofiles which are 7500 mm long with a maximum rectangular cross-section of 120x250 mm.

The maximum output of the line is 665 pieces per hour, which corresponds to 1000m2 per hour.

The power coating shop and its auxiliary equipment have been installed in a shop of 1300 m2. In comparison with standard horizontal lines this space is twice as small; however, vertical lines require a shop which is 13 m high.

What is more interesting and says more about the size and efficiency of the line is the ratio of efficiency per hour to the size of a shop where a powder coating line has been installed. Whereas for standard horizontal lines the ratio is smaller than 0,05, for the vertical line the ratio is not smaller than 1.

Fig. 1 Profiles shifting from horizontal to vertical position in the profile hanging section.

The line consists of the following appliances and processing stations:

  • profile hanging station which consists of a feeding table, profile guides enabling the shifting from horizontal feeding to vertical hanging on the conveyor,
  • conveyor with a lubrication system and furnace for hooks depower coating,
  • chemical processing tunnel,
  • composite construction with a drier and polymerization furnace,
  • spray booth,
  • discharging station with an outfeed table for profiles and profile separator enabling shifting from vertical to horizontal position on the outfeed table,
  • auxiliary equipment: demineralised water station, heat recovery system, air handling unit, sewage pumping station, compressor room.
  • the chemical processing is executed by spraying preparations and water on the surface of profiles.

The sequence of the processes is as follows:

  • acid bath, degreasing and pickling of profiles surfaces,
  • acid pickling,
  • water bath,
  • demineralised water bath,
  • chrome-free passivation,
  • demineralised water bath.

 

Major technological changes take place in higher temperatures, and levels of concentration and types of preparations are based on Alufinish technology.

The use of polymer chrome-free preparations in the forming of a conversion layer is an important innovation.

It is the only spraying installation in Poland which uses chrome-free preparations.

Fig. 2 Tunnel for chemical processing of profiles

The decision about the use of this kind of preparation results from the following factors:

  • the basic motto of YAWAL - "large production, ensuring the highest quality in environment-friendly conditions",
  • raising pro-ecological awareness among the recipients of power coating services and literally demanding to deliver profiles produced in environment-friendly conditions - more and more often it is one of the major conditions for starting cooperation,
  • the requirements of specific Directives of the European Union which aim at gradual decrease, and consequently, elimination of preparations with chrome in the process of chemical processing of aluminum,
  • easy sewage processing and decreasing expenses on the processing.

After the profiles have been chemically processed they are transferred to the drier. Dry profiles are sent on the conveyor to a spray booth. The powder is applied in an automatic booth, where electrostatic guns have been replaced with two OFB4 discs, the construction and working principles of which are protected by international patents held by the supplier of the line, i.e. TRASMETAL (Italy). In addition, the double omega shaped route of the conveyor in the booth provides a proper position of the painted profile against the disc. The result of this solution is even quality and thickness along the circumference of a painted profile.

Unlike the horizontal power coating process, the solutions applied in YAWAL ensure a dispersion of paint thickness of 5–10 µm, whereas in case of the horizontal power coating the dispersion can reach tens of µm.

Fig. 3 Profiles entering and leaving the polymerization furnace.

The booth is equipped with a feeding system, pre-treatment system and powder recovery system, as well as an automatic booth cleaning system used while changing colors. An interesting solution is the walls which are moving while the booth is being cleaned.

The polymerization process is performed in an open-ended continuous furnace with a U-shaped conveyor with a double loop. The process is performed in accordance with the parameters recommended by powder paint manufacturers.

A multi-point temperature measurement system of the furnace together with a unit controlling the furnace and the entire line ensures an easy adjustment of furnace parameters.

The power coating line has been configured and adjusted so that it can cooperate with the Aluminum Profile High Bay Warehouse.

The introduced solutions ensure a flexible and fast flow of materials between the Paint Shop, Profile Warehouse and Finished Goods Warehouse.

The control system enables to continuously monitor production and logistic processes, minimise expenses and shorten the time for customer service. This is the most advanced and unique solution in the country.

Fig. 4 Profile discharging station - profiles shifting from vertical to horizontal position.