WHIRL SINTERING (currently we do not carry this out)
In the whirl sinter process the hot component part is immersed in a fluidified powder bath. Thereby a lacquer coating is created, which must meet certain specifications regarding layer thickness and quality.
For example, the coating of water fittings should be mentioned. In Germany the coating of these component parts must meet the requirements of the GSK (Gemeinschaft schwerer Korrosionsschutz / association for serious corrosion protection). These requirements determine in addition to the pre-treatment of the component parts the qualities of the finished coating, too. Here a coating powder authorised according to the GSK directive must be used, the layer thickness must be within certain limits, or the finished layer must meet certain physical specifications so that the entire component part meets the requirements of the directive.
In the whirl sinter process the preheated component parts must be immersed by a manipulator into the powder bath. Thus touch points result, which are not coated. These points must be chosen in a way that they may be tolerated on the component part.
Before the whirl sintering blasting is generally planned as pre-treatment of the oil- and fat-free component parts. Thereafter the component part must be preheated.
The following types of powders may be used as coating powders:
- and others...
The following powder manufacturers supply whirl sinter powders:
- Akzo Nobel
- Elf Atotech
- and others...
EXPERIENCE / KNOW-HOW
Since the beginning of the 50ies we have had experience with whirl sintering. We used whirl sinter baths with a length of more than 6 m and a width of roughly 2.5 m and a powder height of roughly 1 m. Stands for the cheese storage for German, Austrian and Swiss cheese dairies were coated here.
Based on this experience a machine for small series, called BA-1000, was developed and constructed.
With this machine all small parts, which were hung up in a room of 1x1x1 m, could be preheated automatically and thereafter coated with the linear immersion in a whirl sinter bath.
Care must be taken that the component parts have got suspension hooks. At these suspension points the final coating is not permeable, which means that there is one area which is free to the base material and which is unlacquered.
After the presentation on the Hannover trade fair in 1979 one copy of this machine was sold to a lamp manufacturer. This machine is still being used today.
Based on the BA-1000 we developed an automatic coating plant, BZ-3, which is able to generate reproducible qualities in a whirl sintering process with more than just linear movements.
A more detailed description of this equipment may be found here. Over the course of nearly 10 years the products of German fittings manufacturers for example were coated in various powder qualities with this plant in our company. Also, component parts for the automotive industry such as suction tubes or suspension arm component parts were serially coated.
Whirl sinter plants are rarely erected by a manufacturer. A whirl sinter plant consists of the following components:
- Blasting machine
- Preheating furnace
- Powder bath with suction
- Cooling track
- Coating powder
- Preparation of compressed air
Thus whirl sintering is not a mere immersion of a hot part in the powder. Only if all plant parts are well coordinated, if the operating personnel is well instructed, if the pre-treatment of the component part has been carried out correctly, only then qualitatively outstanding layers are produced with whirl sintering. However, it is often due to the combination of insufficient fine-tuning of the plant components, bad pre-treatment, lacking quality of compressed air and weak instruction of the operating personnel that the coating quality is deteriorating to an extent that it is difficult for the plant operator to find and repair the individual faults.
In such cases we offer our help. We analyse the working process and split the coating process into the individual steps. With our know-how as coaters we point out the individual possible faults and discover lacking combinations so that the plant operator is able to correct the faults and to achieve a better coating. Also, we train your personnel. After the training we can then carry out the process optimisation at the coating plant so that your personnel achieves the best possible with your plant.
Here we collaborate closely with plant manufacturers and powder suppliers so that the plant is planned, designed and run in under correct conditions straight from the onset (see also plant optimisation).