I went to visit Applications Ultrasons in Switzerland and I learned a lot about cleaning, ultrasonic, and about what clean can mean too! You’ll be able to discover a full article on a further issue of Eurotec but for now, let’s dig into cleanliness!
What do you mean by cleanliness?
Mr Pastore, CEO and Mr Margaroli, Sales and Logistic manager with Applications Ultrasons are sure of one thing, cleanliness means a lot for everyone. The only important point is to share the aim.
Basically, we can proceed to 3 different kind of tests.
- Just visual with a microscope or a camera (like the one offered by Marcel Aubert SA)
- Checking the surface energy with a simple system of ink tester (see here below)
- Scanning electron microscope with a resolution of 5 nanometers (to understand what sort of residues there is on the part).
Often we check using the two first methods.
What is surface energy
The surface energy is one decisive criterion for the adhesion of printing ink, glue varnish or any treatment to be done on the part. It is given in mN/m (millinewton per meter) or in dyn/cm (old unit, same numerical value). Apart from some exceptions the general rule is: The higher the surface energy of a material is, the better is the adhesion of anything meant to be fixed to its surface. Contaminations of the surface (grease or oil, finger prints) might be a reason for a low surface energy, which is often the case with metals. As a general limit often 28 mN/m are mentioned: If the surface energy level is below this value, the adhesion will be bad, above this value the adhesion will be good or sufficient. Anyway it is always highly advisable to check the surface energy being necessary for good adhesion for each special application.
How to do that
That’s simple, you can use a batch of special pens with each one its own value. The test pens contain fluids of defined surface tension. The surface energy of the material to be checked is determined simply by applying a stroke of ink with the tip of the felt pen. The accuracy of the measurement is 1 mN/m. The test pens are available in a set of 8 pens from 30 to 44 mN/m. On special demand also bigger or smaller values are available.
Meanwhile, if you want to know more about it, do not hesitate to contact
Route de Trélex 10
1266 Duillier (Suisse)
Tél. + 41 22 364 22 70
Fax + 41 22 364 52 73