The contaminants formed during machining operations must often be removed before dimensional checks can be performed on components. As degreased metal surfaces are prone to corrosion, it is advisable to use a temporary corrosion preventive during any cleaning operations. This is achieved by adding passivating substances to the cleaners or by passivating the metal surfaces in a separate step directly after cleaning. However, many cleaners already contain corrosion inhibitors which provide adequate protection during interim storage.
Cleaning prior to heat treatment and surface coating
Cleaning the surfaces of metal components is absolutely vital prior to any coating processes. Thermochemical and galvanizing operations require absolutely clean and residue-free surfaces for the coating to adhere properly. However, thermochemical and other coating processes made differing demands.
In the case of enameling, there is a particular risk that the high temperatures involved can create traces of organic contaminants. Decomposition can cause enameling imperfections such as scaling, bubbling or poring. Even very little contamination can detrimentally affect the appearance and adhesion of galvanized coatings.
On the other hand, minimal surface contamination can be tolerated in processes such as hot-dip coating (for example hot-dip galvanizing).
The degreasing of metal components prior to painting often involves the application of a thin passivating layer (such as phosphate) which not only provides reliable primary corrosion protection but also guarantees better paint adhesion.
Cleaning as part of maintenance
Plant and machinery which get contaminated during operation must be routinely cleaned. This not only applies to vehicles and all types of manufacturing equipment but also to containers, tanks and finishing lines.