Cleaning all metals with a single detergent can be challenging because different metals have varying reactivity levels and corrosion susceptibility. However, you can follow some general guidelines to clean a wide range of metals effectively.
This blog explores the considerations and guidelines for cleaning different metals. Additionally, we discuss the importance of understanding the sources and types of soils and how to select the appropriate aqueous cleaner for various cleaning processes.
Aluminum is a commonly utilized metal in the manufacturing industry. Aqueous cleaners are effective for degreasing aluminum and typically fall into three categories. Mild alkaline cleaners are the most effective but cause slight etching. Neutral cleaners (5.5 < pH < 8.5) are less effective on heavy soil or loose oxides. Higher pH-inhibited cleaners have no etching and use silicates to prevent aluminum from dissolving.
Steel alloys heavily soiled with grease, grime, and scales are cleaned using highly alkaline or even caustic cleaners. Other types of soils, such as oils, chemicals or particulates such as salts or buffing compounds can be removed with mild alkaline cleaners. Avoid chlorides/halides as they can cause rusting and stress corrosion cracking. Rust-preventative solutions prevent corrosion over time, with varying strengths for short-term indoor storage or outdoor long-term storage.
Copper alloys cannot tolerate aggressive cleaners since they are sensitive to tarnishing by a combination of elevated pH, moisture, and temperature. Keeping the pH below 11 is essential to avoid darkening. If the temperature exceeds 130°F, neutral and mild alkaline cleaners can cause discoloration. Avoid overheating to prevent darkening due to excessively high temperatures when using hot air blow-offs.
Magnesium and its alloys frequently use water-based alkaline cleaning. This is because they are not affected by strong alkaline solutions. However, lower pH solutions can damage magnesium. These materials should be cleaned in solutions with a pH of 11 or higher. Cleaning at milder pH levels is possible but is typically limited to temperatures below 130°F.
Titanium is highly resistant to corrosion and can be cleaned using alkaline cleaners within a pH range of up to 12. Due to the chemical inertness of titanium, alkaline, caustic, and neutral cleaners have very few restrictions. Exceptions include cleaning critical aircraft turbine components, which generally require OEM approval.
Zinc in industrial cleaning applications is rarely encountered in its pure form. However, it is often the principal constituent in a zinc/aluminum alloy casting. Since zinc is a relatively active metal, it is essential to clean it with mild alkaline cleaners. For heavy-duty cleaning or removal of heavy soils, alkaline cleaners with chelating agents may be necessary.
To clean effectively, you must understand the different types of soils generated by various manufacturing processes, which can be categorized as organic or inorganic.
1. Organic soils originate from plant or animal matter and are composed of carbon-based compounds. They can include:
Oils and Greases: These are common contaminants in industrial processes and can be derived from lubricants, cutting fluids, or other sources.
Waxes and Polishing Compounds: These are often used in surface treatments to enhance the appearance and protect against corrosion.
Residues from Lubricants and Metalworking Fluids: Metalworking fluids used during machining operations can leave behind organic residues, contributing to soil buildup.
2. Inorganic soils consist of non-carbon-based compounds and can include:
Oxides and Scale: Metal oxides and scale can form during various manufacturing processes, such as heat treatment or pickling, and may require specialized cleaning methods for removal.
Metal Chips/Fines: Generated during machining or grinding operations can become contaminants and must be effectively removed.
Corrosion Products: Corrosion can result in the formation of various compounds, such as rust, that need to be addressed to ensure surface cleanliness.
The appropriate aqueous cleaner is essential for optimizing the cleaning process when dealing with various materials in the same machine. Consider the following points when choosing a cleaner:
Cleaning Process Compatibility:
Ensure that the chosen cleaner is compatible with the specific cleaning process. Different cleaning methods may require cleaners with particular properties to achieve optimal results. Verify that the cleaner can be applied effectively using the selected process.
Types of Cleaners and Recommended Use:
Various types of aqueous cleaners are designed for specific cleaning tasks. Familiarize yourself with the different types and their recommended uses:
When cleaning different materials in one machine, choosing the right type of cleaner compatible with the cleaning process and the soil type is essential. Efficient cleaning requires the identification of soil sources and types in manufacturing processes. This will ensure that specific soils are efficiently removed without causing damage to the material.
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