Surface treatment

Heraeus has various surface treatment methods which are used to provide a specific surface. These are:

Finishing is a surface treatment process that works on a chemical-mechanical basis. The workpieces and abrasives (chips) are put into the working container of the machine together with a compound and water as bulk material. A relative movement is generated by either a rotation or longitudinal movement of the working container, which results in material removal from the workpiece.

Heraeus uses two types of finishing: barrel finishing, which is the preferred method for large quantities, and vibration finishing for small quantities.

In the barrel finishing method, the workpiece is placed in a horizontal or inclined container, which is rotated around its longitudinal axis. The speed of rotation influences the surface quality. Increasing the rotating speed causes the contents to be lifted and to follow the direction of rotation. At a specific rotating speed, the heavy components glide downwards. The higher the rotating speed, the more material removal occurs and the surface quality get worse. The rotating speed cannot be increased infinitely, because solid components form a depression at the lower end which functions as a brake. Also, it must be ensured that parts do not bounce back and damage the surface of the workpiece. Barrel finishing is only possible up to an angle of 70 degrees.

Barrel finishing is also known as the Trowal process, which comes from the Walther Trowal Company, the first to offer barrel finishing on an industrial scale.

With vibration finishing, the workpiece is put into one or several pots, which are then oscillated using vibrators. The finishing/grinding occurs due to the mass difference between the chip (abrasive) and workpiece during the negative amplitude.

Basin size: length: 3,000 mm x width: 600 mm x height: 1,100 mm

Metals oxidize on the surface due to thermal and mechanical stresses or due to the corrosion process. This oxide layer prevents further processing and must be removed. This is normally done with etching, which means wet chemical treatment in an acid bath. At W. C. Heraeus, the effect of the etchant and removal of surface material can be reduced to the bare minimum for many different metals, thanks to the controlled use of acids. High purity metal surfaces are absolutely necessary to facilitate further processing of our high quality materials. Heraeus uses hydrochloric, sulfuric, hydrofluoric and nitric acid, as well as combinations of these.