The purpose of preparation
Preparation refers to all the operations and purges that are required to ensure that the workpiece’s surface is appropriate for forming the required coating or surface layers.
Less or greater contamination of the surface occurs during the production of the workpiece. A wide range of impurities can be found for example anvil drosses, metallic-oxides, fingerprints, abrasive paste residues, and other variety of impurities.
The appearance of the impurities also shows a wide variety of colors and their adhesion to the surface of the metals can be very different. Besides their physical properties, the chemical characteristics and adherence types determine too how we can remove them.
Surface impurities can be classified into two large groups:
- formed impurities (e.g.: scale, rust)
- adhesive impurities (e.g.: oil, grease, dust).
During preparation, old coatings and other impurities (e.g. rust, scale, abrasive paste residues, fingerprints) are removed from the workpieces.
That is why the correct identification of any foreign materials that may be present on the substrate surface is very important. This will help to determine the most effective and safest method for removing the impurities.
The following methods are used to prepare the workpieces:
- physical-chemical pre-treatment procedures.
These processes makes possible to galvanize the surface.
Different base materials receive different technological treatments.