A Zinc layer applied during the extrusion step creates an extra corrosion protection. The electro-chemical behaviour of Zinc towards aluminium will protect the aluminium from corrosion. The sacrificial behaviour of the Zinc in the possible corrosion process will elongate the life time of the aluminium even more.
Zinc layers of 5-18 gr/m2 can be applied on the tube surface with the use of a twin wire electric arc spray process. The common tolerances of the zinc layer are ± 2 gr/m2.
Different coatings that contain fluxing materials, zinc components and/or braze components like silicon particles or aluminium/silicon particles belong also to the capabilities (product portfolio) at HE Tubing. The Flux coatings are applied on the MPE tube surface in a separate production process after extrusion and before sizing and cutting the MPE to the Customers end specifications. Flux coatings can eliminate the need for fluxing and flux stations at the heat exchanger manufacturer production lines.
Since 2011 has HE Tubing a flux coating line in operation. A multi strand “state of the art” coating line containing a very precise roll coater machine that has the ability to apply a consistent thin coating layer on the aluminium substrate. Depending on the type of coating, a layer thicknesses between 8 and 35 gram / m2 can easily be applied.
HE Tubing produces coated materials according customer specifications which means that for each individual semi finished product the paint mixture has been developed, which makes it possible to achieve the best coating quality combined with the highest productivity. HE Tubing is using the finest components available in the market place in order to make this possible.
HE Tubings laboratory is well equipped to carry out all kind of supporting analysis and investigations on new developed coatings as well on existing coating recipes. In our laboratory we have a “lab-coater” that makes it possible to apply all typical flux braze coatings on laboratory scale. With the use of our braze oven a copy of the customers braze cycle can be simulated. Adjacent to this, SWAAT tests and metallographic analysis can be carried out in our laboratory as well. More deep analysis e.g. mapping of the coating components can be done with our SEM-microscope equipment.
HE Tubing has developed several types of coatings and together with the existing and widely used recipes HE Tubing can offer coating solutions to cover most, if not all of the applications.
The benefits of the use of a flux or braze coating is not only related to costs and environmental issues.
The overall quality of the brazed product can be improved due to the balanced application of a flux-braze coating instead of the use of a more uncontrolled wet fluxing shower.
Besides this the use of a flux-braze coating reduces the number of production steps compared to the traditional process.
The advantages in costs are due to elimination of process equipment, possibly better utilization of the braze furniture (stacking of heat exchangers during brazing), precisely applied coating amount (no spill due to overspray), hardly any uncontrolled contamination of fluxing components with the environment and the possibility to apply zinc enriched components in order to create a galvanic corrosion protection during the same process.