Degreasing
A degreasing is at work pieces necessary to coat to. They must therefore be freed from production-related greasy buildup such as grease , lubricating oils or anti-corrosion oils .
This is done with so-called degreasing agents . These can be organic solvents such as CHC , HFC, CFC or non- halogenated agents. Aqueous solutions are an alternative. For environmental reasons, in recent times only the latter have been used. However, they are not as universally applicable as organic solvents and must therefore be tailored to the specific process .
Degreasing is possible in the acidic to the alkaline range, whereby the extreme agents should be replaced by approximately neutral degreasing agents. However, this requires a higher concentration of wetting agents and surfactants . However, this disadvantage is offset by better environmental compatibility, since wastewater treatment can be carried out more easily and inexpensively. They are also able to saponify animal and vegetable fats ; the wetting agents dissolve non-saponifiable residues into extremely fine particles.
There are various systems in order to be able to perform degreasing economically . The degreasing agent can be sprayed directly onto the workpiece with pressure through nozzles , with the chemical effect being added to the mechanical effect. However, if the workpiece surface is difficult to reach due to its complicated shape, it can be dipped in a degreasing agent. This process requires less energy , but there is no mechanical removal of the residues. In order to solve this problem, ultrasound is also used, which generates micro and macro turbulence in order to remove residues from the smallest cracks and holes. In addition, by cascading the immersion baths, the chemicals can be used much better and water consumption can be reduced significantly.
Another method of degreasing is vibration cleaning .
Under certain circumstances, after degreasing, picking is carried out before the parts are processed further.