Pretreatment
Aabo pretreatment plant is a spray system which is used for:
- Alkali degreasing
- Iron phosphating
- Zinc phosphating
- Chromating
The plant normally consists - depending on the process - of 3-9 spray sections with intermediate air lock sections.
 After the pretreatment process the items are dried in a drying oven. The items are transported through the pretreatment plant by the same conveyor which is used in the following finishing plant.
In the pretreatment sections the items are sprayed by several nozzle units with a pressure of 1-2 kg/cm². The length of the treatment sections depends on the necessary treatment time and conveyor speed.
Pretreatment plants are produced for different treatment processes:
Alkali degreasing is usually carried out in a 2-3 stage plant. The plant gives only a degreasing.
Iron phosphating is carried out in 3-4 stage plantwith low temperature chemicals which provide both degreasing and phosphating. Because of its low energy consumption and simple operation, iron phosphating is at present one of the most utilized systems.
 Zinc phosphating is carried out in a 5- 8 stage plant with alkali degreasing as the first stage. Zinc phosphating gives extra rust protection and good adhesion but it is a rather more costly process as compared to iron phosphating.
Control needs to be careful and qualified which is why the process is primarily used when especially good corrosion protection is required in the finished product.
Chromating is done on a 7-stage plant as a minimum - degreasing/pickling, rinsing, chromating and final rinsing. The advantages of chromating are to give the items a good corrosion protection and improve the adhesion capability of powder, if wanted.
Aabo pretreatment operate with a water saving counter flow system for a fresh water supply - i.e. each stage is automatically supplied with water from the following stage.
 Pretreatment as the above processes can be made as a passage plant, chamber washing machine or a dip plant.
Aabo Maleanlæg has through the years optimized the plants as to the environment and can today offer our great competence within waste water plants with the latest evaporator technique. Here we can work in a completely closed system and re-use the waste water
| 
)
)
)