Proper degreasing of surfaces to be coated
The correct degreasing of surfaces to be coated is a crucial step in the electroplating process. Thorough cleaning is necessary to ensure proper adhesion of the metal coating and to guarantee the quality of the end products. Here are the key steps and methods for effective degreasing:
Why is degreasing important?
- Adhesion: Grease and oil residues can significantly impair the adhesion of the electroplated coating.
- Coating quality: Contamination leads to uneven coatings, blistering and other defects.
- Corrosion protection: Clean surfaces ensure better corrosion resistance of the coated materials.
Degreasing methods
1. chemical degreasing
- Solvent cleaning: Use of organic solvents such as acetone or isopropanol, which effectively dissolve fats and oils.
- Acetone is characterized by its excellent grease solubility and low boiling point. It is mainly used at the institute for cleaning and degreasing tools. Acetone dissolves fingerprints and other light grease well, but is less effective against machine oil. In fact, acetone can be counterproductive on oil-contaminated workpieces, as it can cause dirt particles to adhere permanently to the surface due to adhesive forces.
- Isopropanol (propan-2-ol) can be used in various disciplines and is particularly versatile. It is used, for example, to clean screens or to remove annoying stickers that otherwise leave unpleasant adhesive residue. Isopropanol is particularly suitable for stubborn tasks where other agents fail, as it completely removes residues. Isopropanol leaves no traces as it evaporates without leaving any residue and is chemically neutral to most materials. It can be diluted with distilled water and is well suited for removing oils and greases as well as for cleaning many surfaces.
- Alkaline degreasing: Use of alkaline cleaners that emulsify and remove fats and oils in aqueous solution.
- Acid baths: Acidic cleaning agents are used in some cases, especially when metal oxides or rust need to be removed.
2. mechanical degreasing
- Brushing and grinding: Use of brushes or abrasives to remove coarse contaminants.
- Blasting: Use of abrasives such as glass beads or sand to thoroughly clean the surface.
3. electrolytic degreasing
- Anodic degreasing: The workpieces are suspended as an anode in an alkaline solution and energized, removing grease and oil by gas generation.
- Cathodic degreasing: The workpieces are used as a cathode, which often allows for gentler cleaning.
Steps for degreasing
1. preparation
- Remove coarse dirt and visible impurities by rinsing or mechanical cleaning.
2. chemical or mechanical degreasing
- Application of the selected degreasing method according to the specific requirements of the material and the contamination. For oil-contaminated workpieces, alternative solvents or degreasing methods that are more effective than acetone should be selected.
3. rinsing
- Thoroughly rinse the parts with distilled or deionized water to remove all residues of the degreaser.
4. drying
- Carefully dry the surface to avoid water stains or re-contamination.
Tips for optimum results
- Temperature control: Many degreasing processes are more effective at higher temperatures.
- Controlled environment: Working in a clean environment prevents re-contamination.
- Quality control: Regularly check the surface cleanliness, for example by means of a water drop test or contact angle measurement.
By following these steps and methods, you ensure that the surfaces to be coated are optimally prepared, resulting in a high-quality and long-lasting electroplated coating.
