Hard-water-resistant black metal processing cutting fluid

Abstract

The invention belongs to the technical field of lubricants for metal processing, and discloses a hard-water-resistant black metal processing cutting fluid. The cutting fluid comprises the following components in percentage by mass: 2%-4% of isopropanolamine, 4%-6% of triethanolamine, 3%-6% of an amino acid antirust agent, 0.4%-0.6% of benzotriazole, 4%-8% of 186 self-emulsifying ester, 35%-48% of naphthenic base oil, 4%-6% of tall oil, 3%-4% of Guerbet alcohol, 1.5%-2.5% of an ether carboxylic acid compounding agent and 0.6%-1.8% of EDTA tetrasodium. The invention discloses a water-based cleaning agent, which comprises the following components in percentage by weight: 4-8 percent of ES3054 self-emulsifying ester, 2-4 percent of amide, 4-8 percent of MARLOX RT 64 and the balance of water. The hard-water-resistant black metal processing cutting fluid is environment-friendly, the water-resistant hardness reaches 2000ppm, and the hard-water-resistant black metal processing cutting fluid has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricants for metal processing, and in particular relates to a hard water-resistant ferrous metal processing cutting fluid. Background Art

[0002] Cutting fluid (coolant) is an industrial liquid used to cool and lubricate tools and workpieces during metal cutting and grinding. Cutting fluid is scientifically compounded with a variety of super-functional additives, and has good cooling performance, lubrication performance, rust prevention performance, oil removal and cleaning function, anti-corrosion function, and easy dilution. It overcomes the problems of traditional soap-based emulsions that are easy to stink in summer, difficult to dilute in winter, and have poor anti-rust effect. It has no adverse effects on lathe paint and is suitable for cutting and grinding of ferrous metals. It is currently the most advanced grinding product. All indicators of cutting fluid are better than saponified oil. It has good cooling, cleaning, rust prevention and other characteristics, and is non-corrosive to equipment and non-polluting to the environment.

[0003] The tap water hardness in general areas is within 300ppm, and the requirements for the hard water resistance of metal processing cutting fluids are general, so most of them reach a hardness of about 500-700 after about one year of use, and the requirements for cutting fluids are relatively normal. However, the water hardness in some areas is particularly high (such as Shandong, Hebei, Tianjin, Northeast China, etc.), the initial water quality is about 600-1000ppm, and the hardness can reach about 800-1500 after about one year of use. What's more, a large part of the area is still using groundwater, and the hardness of groundwater is 1500-2000ppm. The requirements for the hard water resistance and comprehensive performance of cutting fluids are extremely high. Existing products have problems with soap precipitation and stratification stability when used in a high hard water environment; they contain a large amount of harmful substances such as boron, formaldehyde, dicyclohexylamine, nitrite, phenol and phenol-based fungicides and VOC volatile substances; in the case of high hard water, the conductivity is high, the rust resistance is insufficient, and the metal corrosion inhibition is poor. At present, conventional solutions generally use ether carboxylic acids to improve hard water resistance, but its effect is limited. Therefore, there is an urgent need to develop a new hard water resistance technology to improve the stability of cutting fluids under high hard water and develop cutting fluids that are environmentally friendly to the human body under high hard water. Summary of the invention

[0004] In order to solve the above technical problems, the present invention develops a hard water resistant ferrous metal machining cutting fluid through formula screening. The cutting fluid is environmentally friendly and hard water resistant.

[0005] On the one hand, the present invention provides a hard water resistant ferrous metal machining cutting fluid, which is composed, by mass percentage, of 2%-4% of isopropanolamine, 4%-6% of triethanolamine, 3%-6% of an amino acid rust inhibitor, 0.4%-0.6% of benzotriazole, 4%-8% of 186 self-emulsifying ester, 35%-48% of cycloalkyl base oil, 4%-6% of tall oil, 3%-4% of Guerbet alcohol, 1.5%-2.5% of an ether carboxylic acid compounding agent, 0.6%-1.8% of tetrasodium EDTA, 4%-8% of ES3054 self-emulsifying ester, 2%-4% of amide, 4%-8% of MARLOX RT 64 and 0%-32.5% of water.

[0006] Furthermore, the hard water resistant ferrous metal machining cutting fluid is composed, by mass percentage, of 3% isopropanolamine, 5% triethanolamine, 4% amino acid rust inhibitor, 0.5% benzotriazole, 6% 186 self-emulsifying ester, 40% cycloalkyl base oil, 5% tall oil, 3% Guerbet alcohol, 2% ether carboxylic acid compounding agent, 1.2% tetrasodium EDTA, 6% ES3054 self-emulsifying ester, 3% amide, 6% MARLOX RT 64 and 15.3% water.

[0007] On the other hand, the present invention provides a method for preparing the ferrous metalworking cutting fluid, the method for preparing the ferrous metalworking cutting fluid comprising the following steps:

[0008] Step 1, weighing the raw materials of each component according to the mass percentage of each component of the ferrous metal processing cutting fluid;

[0009] Step 2: Add water, isopropanolamine, amino acid rust inhibitor, benzotriazole and triethanolamine into a 250 mL beaker and stir until uniform and transparent;

[0010] Step 3: Add 186 self-emulsifying ester, tall oil, base oil, Guerbet alcohol, ether carboxylic acid compounding agent, tetrasodium EDTA, MARLOX RT 64, ES3054 self-emulsifying ester and amide to the uniform transparent liquid prepared in step 1, and stir until it becomes uniform and transparent.

[0011] Furthermore, in the method for preparing the ferrous metal processing cutting fluid, the stirring temperature in step 2 is room temperature.

[0012] Furthermore, in the method for preparing the ferrous metal machining cutting fluid, the stirring temperature in step three is 40°C.

[0013] In addition, the present invention provides application of the hard water resistant ferrous metal machining cutting fluid in ferrous metal machining.

[0014] Compared with the prior art, the present invention has at least the following advantages or beneficial effects:

[0015] (1) The present invention obtains a hard water resistant ferrous metal machining cutting fluid by screening a large number of formula components and formula research and development. The hard water resistant ferrous metal machining cutting fluid is composed of 2%-4% of isopropanolamine, 4%-6% of triethanolamine, 3%-6% of amino acid rust inhibitor, 0.4%-0.6% of benzotriazole, 4%-8% of 186 self-emulsifying ester, 35%-48% of cycloalkyl base oil, 4%-6% of tall oil, 3%-4% of Guerbet alcohol, 1.5%-2.5% of ether carboxylic acid compounding agent, 0.6%-1.8% of tetrasodium EDTA, 4%-8% of ES3054 self-emulsifying ester, 2%-4% of amide, 4%-8% of MARLOXRT 64 and 0%-32.5% of water in terms of mass percentage.

[0016] (2) The hard water resistant ferrous metal machining cutting fluid does not contain any substances harmful to the human body, such as boron, formaldehyde, dicyclohexylamine, nitrite, phenol, phenol-based fungicides, and VOC volatiles.

[0017] (3) This hard water resistant ferrous metal machining cutting fluid has excellent anti-rust performance and is not prone to rust during use, thus extending the product shelf life, protecting the machine from corrosion, saving raw materials, and protecting the environment.

[0018] (4) This hard water resistant ferrous metalworking cutting fluid has excellent hard water resistance and can be maintained evenly and stably at 2000ppm. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described below in conjunction with embodiments; however, the present invention is not limited to the following embodiments.

[0020] The experimental methods and detection methods in the following embodiments are all conventional methods unless otherwise specified; the raw materials and materials are all commercially available unless otherwise specified; the index data are all conventional measurement methods unless otherwise specified.

[0021] Ferrous metals: Ferrous metals mainly refer to iron and its alloys, such as steel, pig iron, iron alloys, cast iron, etc. Metals other than ferrous metals are called non-ferrous metals.

[0022] "4-dimensional" complexation technology: improves hard water resistance from four dimensions, and the hard water resistance provided by each dimension has its own advantages.

[0023] Cutting fluid: Cutting fluid (coolant) is an industrial liquid used in the process of metal cutting and grinding to cool and lubricate tools and workpieces. Cutting fluid is scientifically compounded with a variety of super-functional additives. It has good cooling performance, lubrication performance, rust prevention performance, oil removal and cleaning function, anti-corrosion function, and easy dilution.

[0024] High hardness water: Regular water contains certain salt substances, such as calcium salts and magnesium salts. When the amount of calcium salts and magnesium salts exceeds a certain amount and the hardness exceeds 500ppm or even exceeds 1000ppm, it is considered high hardness water.

[0025] Triethanolamine: Triethanolamine, also known as tri(2-hydroxyethyl)amine, is an organic compound with the chemical formula C6H 15 NO3. Triethanolamine is weakly alkaline and can react with inorganic or organic acids to form salts. It is used as a rust inhibitor in cutting fluids.

[0026] Isopropanolamine: Isopropanolamine is an important corrosion inhibitor that can be used in boiler water treatment, automobile engine coolant, drilling and cutting oil and other types of lubricants to inhibit corrosion.

[0027] Amino acid rust inhibitor: It has good rust prevention, extremely low foaming, good hard water stability, and the solution within the commonly used concentration range is non-irritating to the skin and mucous membranes. It is mainly used as a metal corrosion inhibitor additive in semi-synthetic cutting fluids, fully synthetic grinding fluids, water-based quenching fluids and water-based cleaning agents, automotive antifreeze, rust-proof water and other water-based products.

[0028] Benzotriazole: Mainly used as water treatment agent, metal rust preventer and corrosion inhibitor. Widely used in circulating water treatment agent, anti-rust oil, lipid products, also used in copper and copper alloy vapor phase corrosion inhibitor, lubricant additives. Used for surface purification of silver, copper, zinc in electroplating, it has anti-discoloration effect. BTA forms covalent bonds and coordination bonds with copper atoms, and replaces each other to form chain polymers, forming a multi-layer protective film on the surface of copper, so that the copper surface does not undergo redox reaction, does not generate hydrogen, and has an anti-corrosion effect. It also has the same effect on metal materials such as lead, cast iron, nickel, zinc, etc. BTA can be combined with a variety of corrosion inhibitors to improve the corrosion inhibition effect.

[0029] 186 Self-emulsifying ester: It is an ashless high molecular weight ester lubricant. It is widely used in metalworking cutting fluids and industrial lubricants. Since it does not contain chlorine, sulfur, or phosphorus, it can replace chlorine- and sulfur-containing extreme pressure additives in soluble oils and semi-synthetic products; this synthetic ester product also has good hydrolysis stability.

[0030] Tall oil: Mainly used as an emulsifier and auxiliary lubricant. It is an unsaturated fatty acid and has better resistance to corruption than oleic acid.

[0031] Cycloalkane base oil: good low temperature performance, easy to emulsify, good compatibility with additives.

[0032] Guerbet alcohol: Guerbet alcohol is a general term for a class of fatty alcohols with a branched chain on the second carbon, also known as 2-alkyl-1-alkanol, which is a class of saturated primary alcohols. Due to the special structure of two 100% linear alkyl chains, it has the following characteristics: 1) low volatility; 2) low irritation; 3) low freezing point; 4) excellent lubricity; 5) excellent oxidation stability; 6) good solubility and dissolving power; 7) low viscosity; 8) good biodegradability.

[0033] Ether carboxylic acid compounding agent: excellent resistance to hard water, and Ca in water 2+ ,Mg 2+ Chelation, and the generated chelate has good dispersing effect; low foaming performance, the use of the liquid will not produce a lot of foam; environmentally friendly, low toxicity, and has excellent biodegradability.

[0034] EDTA4NA: EDTA tetrasodium is an organic compound with the molecular formula C 10 H 12 N2Na4O8, molecular weight 380.17, white powder. Easily soluble in water, used as hard water softener and multivalent chelating agent.

[0035] ISA ES3054 self-emulsifying ester: It is a self-emulsifying ester that is easy to emulsify and can inhibit the generation of hydrogen. It has a special molecular structure and has strong emulsification after neutralization with amines. It has a hydrophilic carboxyl group, can bind calcium and magnesium ions, and has good dispersion, excellent hard water resistance, and excellent lubricity.

[0036] MARLOX RT 64: A versatile hydrophobic emulsifier for water-based metalworking cutting fluids with excellent low foaming properties, excellent calcium soap dispersing ability and easy biodegradability.

[0037] Amide: An organic compound in which the hydroxyl group in the carboxylic acid is replaced by an amino group or an amine group. It is mainly used as an industrial solvent. It is a multifunctional emulsifier and has an auxiliary lubricating and rust-proofing effect.

[0038] Example 1

[0039] This embodiment is for preparing a hard water resistant ferrous metal machining cutting fluid.

[0040] Weigh 2% of isopropanolamine, 4% of triethanolamine, 3% of amino acid rust inhibitor, 0.4% of benzotriazole, 4% of 186 self-emulsifying ester, 35% of cycloalkyl base oil, 4% of tall oil, 3% of Guerbet alcohol, 1.5% of ether carboxylic acid compounding agent, 0.6% of tetrasodium EDTA, 4% of ES3054 self-emulsifying ester, 2% of amide, 4% of MARLOXRT 64, and the balance of water for standby use.

[0041] First, add water, isopropanolamine, amino acid rust inhibitor, benzotriazole, and triethanolamine into a 250 mL beaker and stir at room temperature until it is uniform and transparent. Then add 186 self-emulsifying ester, tall oil, base oil, Guerbet alcohol, ether carboxylic acid compounding agent, tetrasodium EDTA, MARLOX RT 64, ES3054 self-emulsifying ester, and amide into the above uniform and transparent liquid and stir at 40°C until it is uniform and transparent to obtain 1# hard water resistant black metal processing cutting fluid.

[0042] Example 2

[0043] This embodiment is for preparing a hard water resistant ferrous metal machining cutting fluid.

[0044] Weigh 3% of isopropanolamine, 5% of triethanolamine, 4% of amino acid rust inhibitor, 0.5% of benzotriazole, 6% of 186 self-emulsifying ester, 40% of cycloalkyl base oil, 5% of tall oil, 3% of Guerbet alcohol, 2% of ether carboxylic acid compounding agent, 1.2% of tetrasodium EDTA, 6% of ES3054 self-emulsifying ester, 3% of amide, 6% of MARLOXRT 64, and the balance of water for standby use.

[0045] First, add water, isopropanolamine, amino acid rust inhibitor, benzotriazole, and triethanolamine into a 250 mL beaker and stir at room temperature until it is uniform and transparent. Then add 186 self-emulsifying ester, tall oil, base oil, Guerbet alcohol, ether carboxylic acid compounding agent, tetrasodium EDTA, MARLOX RT 64, ES3054 self-emulsifying ester, and amide into the above uniform and transparent liquid and stir at 40°C until it is uniform and transparent to obtain 2# hard water resistant black metal processing cutting fluid.

[0046] Example 3

[0047] This embodiment is for preparing a hard water resistant ferrous metal machining cutting fluid.

[0048] Weigh 4% of isopropanolamine, 6% of triethanolamine, 6% of amino acid rust inhibitor, 0.6% of benzotriazole, 4% of 186 self-emulsifying ester, 42% of cycloalkyl base oil, 6% of tall oil, 4% of Guerbet alcohol, 2.5% of ether carboxylic acid compounding agent, 1.8% of tetrasodium EDTA, 8% of ES3054 self-emulsifying ester, 4% of amide, 8% of MARLOXRT 64, and the balance of water for standby use.

[0049] First, add water, isopropanolamine, amino acid rust inhibitor, benzotriazole, and triethanolamine into a 250 mL beaker and stir at room temperature until it is uniform and transparent. Then add 186 self-emulsifying ester, tall oil, base oil, Guerbet alcohol, ether carboxylic acid compounding agent, tetrasodium EDTA, MARLOX RT 64, ES3054 self-emulsifying ester, and amide into the above uniform and transparent liquid and stir at 40°C until it is uniform and transparent to obtain 3# hard water resistant black metal processing cutting fluid.

[0050] Example 4

[0051] This embodiment is for preparing a hard water resistant ferrous metal machining cutting fluid.

[0052] Weigh 2% of isopropanolamine, 4% of triethanolamine, 3% of amino acid rust inhibitor, 0.6% of benzotriazole, 8% of 186 self-emulsifying ester, 48% of cycloalkyl base oil, 6% of tall oil, 4% of Guerbet alcohol, 2.5% of ether carboxylic acid compounding agent, 1.8% of tetrasodium EDTA, 8% of ES3054 self-emulsifying ester, 4% of amide, 8% of MARLOXRT 64, and the balance of water for standby use.

[0053] First, add water, isopropanolamine, amino acid rust inhibitor, benzotriazole, and triethanolamine into a 250 mL beaker and stir at room temperature until it is uniform and transparent. Then add 186 self-emulsifying ester, tall oil, base oil, Guerbet alcohol, ether carboxylic acid compounding agent, tetrasodium EDTA, MARLOX RT 64, ES3054 self-emulsifying ester, and amide into the above uniform and transparent liquid and stir at 40°C until it is uniform and transparent to obtain 4# hard water resistant black metal processing cutting fluid.

[0054] Example 5

[0055] This embodiment is a test for detecting harmful substances in different metalworking cutting fluids.

[0056] Two common semi-synthetic cutting fluids (A and B) with good hard water resistance (for use in the north) on the market were selected for comparative experiments with the cutting fluids of the present invention (1#-4# cutting fluids prepared in Examples 1-4). The factors used in the comparative experiments, such as pure water, nitrite test paper, formaldehyde test paper, tapping torque meter, cast iron chips, and experimental environment, were all kept consistent, and the only variable was the different types of metalworking cutting fluids.

[0057] The 6 metalworking cutting fluids were tested for chlorine content, and then diluted with 5% pure water to test the contents of boron, formaldehyde, and nitrite. The results are shown in Table 1.

[0058] Table 1 Detection results of harmful substances in different metalworking cutting fluids

[0059] Metalworking cutting fluid model Whether it contains chlorine Does it contain nitrite? Does it contain boron? Whether it contains formaldehyde 1# Patented cutting fluid Not included Not included Not included Not included 2# Patented cutting fluid Not included Not included Not included Not included 3# Patented cutting fluid Not included Not included Not included Not included 4# Patented cutting fluid Not included Not included Not included Not included Semi-synthetic A type Contains Not included Contains Contains Fully synthetic B type Not included Not included Contains Not included

[0060] The test results are shown in Table 1. The results show that the patented cutting fluids do not contain harmful substances such as nitrosamine, formaldehyde, and boron, while the semi-synthetic A-type metalworking cutting fluid and the fully synthetic B-type metalworking cutting fluid both contain one or more harmful substances. The test results show that the patented cutting fluid does not contain harmful substances and is environmentally friendly.

[0061] Example 6

[0062] This embodiment is a test of the lubricity of different metalworking cutting fluids.

[0063] Two common semi-synthetic cutting fluids (type A) and fully synthetic type B with good hard water resistance (for use in the north) on the market were selected for comparative experiments with the cutting fluids of the present invention (cutting fluids 1#-4# prepared in Examples 1-4).

[0064] The above metalworking cutting fluids were prepared into tap water dilutions with a concentration of 10 wt %, and then the lubricity was tested using a tapping torque meter. The results are shown in Table 2.

[0065] Table 2 Lubricity test results of different metalworking cutting fluids

[0066] Metalworking cutting fluid model Lubricity 1# Patented cutting fluid 64.5Ncm 2# Patented cutting fluid 64.4Ncm 3# Patented cutting fluid 64.5Ncm 4# Patented cutting fluid 64.5Ncm Semi-synthetic A type 74.3Ncm Fully synthetic B type 98.5Ncm

[0067] The test results are shown in Table 2. The results show that the lubrication performance of patented cutting fluids 1#-4# is better than that of the comparative cutting fluids, and patented cutting fluid 2# has the best performance. Semi-synthetic A-type metalworking fluid is inferior to patented cutting fluid in lubricity, and fully synthetic B-type metalworking fluid has the worst lubricity. The results show that the patented cutting fluid has good lubricity, can meet demanding processing technology, and can achieve good processing results at a lower concentration.

[0068] Example 7

[0069] This embodiment is a test for the rust prevention performance of different metalworking cutting fluids.

[0070] Two common semi-synthetic cutting fluids (type A) and fully synthetic type B with good hard water resistance (for use in the north) on the market were selected for comparative experiments with the cutting fluids of the present invention (cutting fluids 1#-4# prepared in Examples 1-4).

[0071] The above metalworking cutting fluid was prepared into 5wt% and 3wt% tap water dilutions, and then the anti-rust performance of the cutting fluid was tested by the cast iron chips method. The results are shown in Table 3.

[0072] Table 3 Test results of anti-rust performance of different metalworking cutting fluids

[0073] Metalworking cutting fluid model 5wt% tap water dilution 3wt% tap water dilution 1# Patented cutting fluid Level 0 Level 0 2# Patented cutting fluid Level 0 Level 0 3# Patented cutting fluid Level 0 Level 0 4# Patented cutting fluid Level 0 Level 0 Semi-synthetic A type Level 1 Level 3 Fully synthetic B type Level 1 Level 2

[0074] The test results are shown in Table 3. The results show that the anti-rust performance of the 1#-4# patented cutting fluids is better than that of the comparative cutting fluids, indicating that the anti-rust performance of the patented cutting fluids is better than that of the comparative cutting fluids.

[0075] Example 8

[0076] This embodiment is a test for testing the hard water resistance of different metalworking cutting fluids.

[0077] Two common semi-synthetic cutting fluids (type A) and fully synthetic type B with good hard water resistance (for use in the north) on the market were selected for comparative experiments with the cutting fluids of the present invention (cutting fluids 1#-4# prepared in Examples 1-4).

[0078] The above metalworking cutting fluid was formulated into 1000ppm and 2000ppm hard water, and the hard water resistance was tested. The test results are shown in Table 4.

[0079] Table 4 Test results of hard water resistance of different metalworking cutting fluids

[0080]

[0081]

[0082] The test results are shown in Table 3. The results show that the 1#-4# patented cutting fluids are uniform and stable at 2000ppm, and there is no precipitation and stratification. The semi-synthetic cutting fluid shows slight soap precipitation at 1000ppm, but obvious stratification and precipitation at 2000ppm. All effective substances of the fully synthetic cutting fluid are precipitated under high hardness water.

[0083] As described above, the present invention can be well implemented. The above embodiments only describe the preferred implementation methods of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various changes and improvements made to the technical scheme of the present invention by ordinary technicians in this field should fall within the protection scope determined by the present invention.

Claims

1. A hard water resistant ferrous metal machining cutting fluid, characterized in that: The hard water resistant black metal machining cutting fluid consists of, by mass percentage, 2%-4% of isopropanolamine, 4%-6% of triethanolamine, 3%-6% of amino acid rust inhibitor, 0.4%-0.6% of benzotriazole, 4%-8% of 186 self-emulsifying ester, 35%-48% of cycloalkyl base oil, 4%-6% of tall oil, 3%-4% of Guerbet alcohol, 1.5%-2.5% of ether carboxylic acid compounding agent, 0.6%-1.8% of tetrasodium EDTA, 4%-8% of ES3054 self-emulsifying ester, 2%-4% of amide, 4%-8% of MARLOX RT 64 and 0%-32.5% of water.

2. The hard water resistant ferrous metalworking cutting fluid according to claim 1, characterized in that: The hard water resistant black metal machining cutting fluid consists of 3% of isopropanolamine, 5% of triethanolamine, 4% of amino acid rust inhibitor, 0.5% of benzotriazole, 6% of 186 self-emulsifying ester, 40% of cycloalkyl base oil, 5% of tall oil, 3% of Guerbet alcohol, 2% of ether carboxylic acid compounding agent, 1.2% of tetrasodium EDTA, 6% of ES3054 self-emulsifying ester, 3% of amide, 6% of MARLOX RT64 and 15.3% of water in percentage by mass.

3. The method for preparing a ferrous metal machining cutting fluid according to claim 1, characterized in that: The steps include: Step 1, weighing the raw materials of each component according to the mass percentage of each component of the ferrous metal processing cutting fluid; Step 2: Add water, isopropanolamine, amino acid rust inhibitor, benzotriazole and triethanolamine into a 250 mL beaker and stir until uniform and transparent; Step 3: Add 186 self-emulsifying ester, tall oil, base oil, Guerbet alcohol, ether carboxylic acid compounding agent, tetrasodium EDTA, MARLOX RT 64, ES3054 self-emulsifying ester and amide to the uniform transparent liquid prepared in step 1, and stir until it becomes uniform and transparent.

4. The method for preparing a ferrous metal machining cutting fluid according to claim 3, characterized in that: The stirring temperature in the step 2 is room temperature.

5. The method for preparing a ferrous metal machining cutting fluid according to claim 3, characterized in that: The stirring temperature in step 3 is 40°C.

6. Application of the hard water resistant ferrous metal machining cutting fluid of claim 1 in ferrous metal machining.

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