Water-based metalworking fluid 1
I. Characteristics of Water-Based Metalworking Fluids
1. Alkaline pH: 8 - 9.5. Although this is not the most suitable pH for microorganisms, it does not affect their rapid proliferation.
2. Temperature: The low temperature is sufficient to support the growth and reproduction of microorganisms, but not so high as to inhibit their growth.
3. Usually contains a high percentage of water.
4. The components contain sufficient nutrients.
5. Recycling and the introduction of oxygen at the same time are beneficial for the reproduction of microorganisms.
6. The flow rate is insufficient to prevent the formation of biofilms.
7. Carrying waste and self-pollution
II. Common Microorganisms Found in Water-Based Metalworking Fluids
Bacteria:
Anaerobic bacteria (common examples include sulfate-reducing bacteria, which produce substances such as hydrogen sulfide)
Aerobic bacteria such as Escherichia coli, Pseudomonas, Staphylococcus aureus, Bacillus subtilis, etc.
Fungi
Molds: Aspergillus, Penicillium, Rhizopus, Cephalosporium, etc.
Yeast: Red yeast, beer yeast, Candida yeast, etc.
III. Three Hazards of Microorganisms to Metalworking Fluids
Metalworking fluids, especially water-based metalworking fluids and emulsions, are fertile breeding grounds for microorganisms.
(1) During the usage process, if they are allowed to grow and multiply without any restrictions, it will cause the processing liquid to deteriorate and lose its performance.
(2) Corrosive processing fluids can damage the processing machines, clog the processing fluid treatment system, and harm the processing tools and the processed workpieces.
(3) The growth and reproduction of microorganisms can produce foul odors and related compounds, which can affect the factory's environment, irritate the skin of the operators and cause allergic reactions, thereby endangering the health of the workers.
IV. Specific Problems Caused by Microorganisms to Metalworking Fluids (Water-Based)
The working fluid has become smelly, discolored and cloudy.
2. The emulsified state is unstable, with oil and water separating.
3. There are sticky deposits on the metal surface or in the oil tank, which block the oil passage or the filter.
4. Decrease in pH value
5. Causing corrosion to the equipment
6. The trend of bubble formation is increasing.
7. Decrease in cutting ability
V. Requirements for Bactericides for Metalworking Fluids
Broad-spectrum and highly effective, it is effective against bacteria, fungi, and even algae.
2. It must take effect at a low concentration (so that its concentrated solution can achieve a sterilization effect when diluted at ratios of 1:10, 1:15, or even 1:20).
3. Maintain its chemical stability for a long time under harsh conditions (such as high pH and even certain high temperatures)
4. Reasonable cost for use
5. Stay within the permitted limits as stipulated by environmental regulations.
VI. Classification of Main Components of Bactericidal and Antimicrobial Agents in the Current Cutting Fluid Industry
Triazine class
BK is also known as Sida Oil. Its chemical name is 1,3,5-tris(2-hydroxyethyl)-hexahydropyrazine. It was first developed successfully by the Shanghai Institute of Pesticides in China and belongs to a water-based, low-toxicity fungicide. It is suitable for high pH and high-temperature environments.
Bactericide BK is a widely used bactericide in metalworking fluids. It can be used in concentrated solutions or for on-site treatment. The dosage in concentrated solutions is 2-5%; the dosage for on-site sterilization is: 0.1-0.25%. Currently, the main bactericides in the cutting fluid industry are mainly bactericides with triazine (BK) as the main component (this product is a type of slow-release formaldehyde-based release agent). Because it can generally adapt to the alkaline pH value of the cutting fluid (the pH value of the cutting fluid is generally in the range of 9-10), combined with its broad-spectrum bactericidal effect, moderate price, it is still widely adopted by many manufacturers and can be used in combination with fungicides.
2. Morpholine
MBM belongs to the class of morpholine derivatives. Its chemical name is N,N'-methylene bismorpholine. It is a broad-spectrum and highly effective fungicide. It has a long duration of action, low odor, a pH range of 4-12, low skin irritation, good compatibility in emulsified oils, and is generally recommended at a dosage of 0.1-0.3% of the total weight of the product. It can be used in combination with fungicides.
3. Oxazoline class
Oxazolin fungicide is a broad-spectrum fungicide, especially effective against sulfate-reducing bacteria. It has a long-lasting effect, a low odor, a pH range of 7-11, no skin sensitization effect, and good safety. It also has amine functions, is corrosion-resistant, has pH buffering capacity under alkaline conditions, and maintains the viscosity of the emulsion. The general working solution concentration is 0.04-0.2%, and it can be used in combination with fungicides.
