Developing a new paint system is a complex task. In addition to color, shade, viscosity, surface properties and chemical composition, the behavior of the material during application must also be taken into account.
A paint that has the desired material properties in the laboratory will therefore not necessarily produce the desired spray structure with the existing atomizers.
After every significant change to a paint system, the application parameters often have to be redetermined as well. For rotary atomizers, these include rotational speed, material flow, shaping air and other process parameters.
Fine-tuning these variables requires extensive test series and a great deal of experience.
The Spray as a Common Evaluation Criterion
One approach is to look not only at the individual machine parameters but to measure their result directly: the spray produced.
The following can be investigated in particular:
- droplet size,
- droplet velocity,
- spatial differences within the spray,
- optical properties of the droplets and
- changes in material characteristics.
The result is a common measured variable that allows different paints and different settings of a rotary atomizer to be compared with one another.
LSS4 and ParticleTensorAI® for Advanced Investigations
The LSS4 multichannel measurement probe is well suited for research and development tasks.
Multiple optical signals from a single droplet provide additional information on its motion and optical properties. In combination with ParticleTensorAI®, the continuously acquired signals are processed as multidimensional datasets.
This enables detailed comparisons of different paint systems and atomization conditions – especially when material-dependent differences are to be investigated in addition to size and velocity.
If droplet size, velocity and the temporal stability of the spray are the main requirements, SprayQuantAI® can be used as an alternative.
Considering Droplet Size and Velocity Together
The effect of a droplet in the painting process depends not only on its diameter but also on its velocity.
Further variables describing the dynamics of the spray can be derived from droplet size and the velocity vector.
This allows different operating points of a rotary atomizer to be compared not just on the basis of individual machine parameters, but on the basis of the droplet population actually produced.
Target Values for Paint Development
Once a suitable spray state has been determined for an existing, well-functioning coating process, it can serve as a reference.
When a new paint system is introduced, the atomizer parameters are then adjusted until a comparable spray state is achieved again.
The question in development thus changes from
“Which settings work with this paint?”
to
“Which settings achieve the desired spray state?”
Optical spray measurement provides immediate feedback during the trials. Parameter changes can be evaluated instantly, and unnecessary test steps are avoided.
SprayQuantAI® and ParticleTensorAI® thus help make the development and commissioning of new paint systems more systematic and data-driven.