- Earthing of parts to be painted must be as correct as possible and checked regularly to avoid application issues and differences in the aspect.
- It is important to notice that metallic powder coatings must be used with a hopper to maintain a proper homogeneous fluidized bed, level ¾ high, in order to avoid possible separation.
- Settings must be adjusted to achieve the right aspect; as a guide we recommend working with constant 80 kV high voltage while the intensity should be adjusted according to the part to be painted.
- Super corona counter electrodes are usually used to increase the flow of the film on large flat surfaces but are not recommended when applying metallic powder paints because they tend to modify and reduce the electrostatic field and this can influence the final aspect. In case of use, a prototype must be produced for customer approval to validate the aspect.
- Best spraying results are obtained with an automatic mode and a distance between spray guns and parts at least 25/35 cm.
- If objects have two or more main surfaces and the spray guns are offset, this can result in effect variations, for instance due to major differences in the distance between guns and items to be coated. Ensure alignment of the items if possible.
- The speed of the line should be adjusted according to the number of spray guns, the distance between spray guns and parts, the type of nozzles and the reciprocator speed (W adjustments) in order to avoid shading/clouding.
- Manual application might be irregular, leading to variation of the aspect. If the part to be painted is complex (requiring pre touch-in with a manual gun prior to automatic application), we encourage making a preliminary trial to qualify the aspect and establish all parameters before starting the job. Post touch-in (with a manual gun after automatic application) is not recommended.
- The pre touch-in stage must start with difficult parts to be painted like welds, Faraday cage effects etc. The automatic stage allows the film thickness and final aspect to be harmonised.
- When automatic application is not possible (only manual), the operator should start by spraying the difficult areas and then increase the distance between part and gun to harmonize thickness and aspect in order to avoid clouding.
- Whatever the process, the film thickness should be as uniform as possible to limit colour variations.
- Tribostatic and corona equipment, but also equipment different suppliers, might lead to possible difference in the final aspect, so we recommend that one single equipment is defined and used for each job.
- Aspect/colour might be influenced by reclaiming the overspray ; care must be taken to ensure an appropriate ratio (maximum 30 % for bonded products, depending on the contrast and metallic aspect – please contact your local representative for advice). Reclaiming should be automatic. Good practice is to work at “constant level”, which means having a large quantity of powder in the hopper. Best practice is to use 3 hoppers, one for virgin powder, one for reclaimed powder and the last one for the blend at the right ratio.
In any case, a frequent visual inspection is necessary when reclaiming the overspray to validate the colour and appearance.
- Once defined, parameters and settings should be recorded for future applications.