Functions of Cutting Oil( Liquid)
1. Cooling: prevent hardness loss of cutter and over heating of workpieces; lengthen the life of cutter; improve machining precision.
2. Lubrication: reduce cutting resistance; lower friction between cutters, workpieces and swarfs.
3. Rust inhibition: prevent corrosion for devices and workpieces.
 
Types of Cutting Oil (Liquid)
1. Straight Cutting Oil: Oils that are not diluted with water before use.
2. Water-soluble Cutting Liquid: Oils that are diluted with large quantity of water before use.
 
Components of Straight Cutting Oil
Mineral oil, fatty oil, sulfurized extreme pressure agent, antioxidant, rust inhibitor, defoamer, nonferrous metal corrosion inhibitor, oil mist inhibition agent.
 
Components of Water-soluble Cutting Liquid
Mineral oil, fatty oil, fatty acid, extreme pressure additive, surfactant, amine, inorganic salt, organic rust inhabitor, inorganic rust inhibitor, nonferrous metal passivator, corrosion inhabitor, defoamer, water and etc..
 
Test Items of Straight Cutting Oil
Viscidity, flash point, pour point, fat content, chlorine content, copper corrosion, moisture content, mechanical impurities and etc..
 
Management of Straight Oil

Item	Purpose	Target
Appearance	Check if liquids are contaminated or deteriorated because of impurities(metal powders, water and etc.).	No apparent color change.
Dye(ASTM)	Check the degree of dye.	No specific target.
Concentration(ｇ/cm3，15℃)	Check if impure oil is mixed with the liquid/oil.	Concentration for new liquid ±0.02
Viscidity (mm2/s、40℃）	Check if impure oil is mixed with the liquid/oil; if the liquid/oil deteriorates.	Viscidity for new liquid±30%
Flash Point(℃、COC）	Check if low flash point ingredients( kerosene and etc.) are mixed with the liquid/oil.	No apparent reducing.
Copper Corrosion(100℃、1hr）	Analyze oil's influence over workpieces and copper alloy (degree of corrosion).	Equals the new liquid.
Additive Content	Analyze the first performance of the liquid/oil and its impure oil content.	Above 70% of the additive content for new liquid.
Impure Oil Content	Analyze the first performance of the liquid/oil and its impure oil content.	Below 80%.
Moisture Content	Analyze effects upon workpieces(rust prevention\ corrosion prevention) and upon oil ingredients(water decomposition).	Below 0.1%.

 
Test Items of Water-Soluble Cutting Liquid
Concentration, PH level, impure oil content, rust prevention, bacteria, hardness, chloride ion, sulfate ion and etc..
 
Management of Water-Soluble Cutting Liquid

Item	Management Target	Management Method
Appearance	Check the degree of contamination of liquid; check if liquid deteriorates.	Visual inspection
Fragrance	Check if deterioration occurs.	Smell
Oil Concentration	Consistency of the first and secondary performance of the liquid.	Saccharometer
PH Level	Rust Prevention; Degree of deterioration.	PH meter or PH test paper
Impure Oil Content	Rust Prevention	Visual inspection
Adding Amount of New Water-Soluble Cutting Liquid and Dilution Water.	Evaluate the concentration of the liquid.	Usage amount
Adding Amount of Lubrication Oil and Hydraulic Oil.	Evaluate mixing volume of lubrication oil and hydraulic oil.	Usage amount

 
Troubleshooting Strategies when Applying Water-Soluble Cutting Liquids

Problem	Cause	Strategy
1. Tool life reduces and processing accuracy worsens.	1. Changes on processing condition 2. Mechanical loss caused by insufficient lubrication on point of cutter	1. Check if processing conditions and workpiece materials change. If so, alter it to the default processing condition 2. Check if oil supply quantity or oil supply pressure changes. If so, adjust them within the default parameter range. If problem still exists, raise oil delivery quantity and oil supply pressure to improve oil supply conditions. 3. Check if liquid concentration is within the range of management targets. Concentration shall be altered to the recommended range. If problem still exists, raise concentration as far as possible.
2. Rotten odor is produced.	Liquid deteriorates.	1. Check if PH value and concentration are within management range→ if liquid apparently deteriorates, replace it with new liquid. If the status of use solution is recoverable, its concentration shall be altered to normal range. Add PH value improver （WH-1,1000ppm） and corrosion inhibitor （WB-2,1000ppm）. 2. Check if impure oil is mixed with the liquid. If so, remove it. 3. If deterioration constantly occurs on the same machine tool, entrust the manufacturer of the cutting liquid to investigate the cause.
3. Low PH Value	1. Low concentration 2. Worsened condition of liquid	1. Check if concentration is within the management target→ if concentration is lower than the management target, add new cutting liquid. If concentration is normal, add PH improver(WH-1orWH-3、1000ppm) when PH level is low. 2. If liquid apparently deteriorates or corrodes, handle it in accordance with strategies mentioned above.
4. Machine tools and  workpieces rust.	1. Adding water only leads to low concentration of liquid coolant. 2. Worsened liquid coolant. 3. High concentration of chloride ion and sulfate ion in dilution water 4. Processed parts stay on production line too long.		1. Test pH value and concentration. Adjust pH value and concentration to be within administrative control value. If concentration is normal and pH value is too low, add pH value   improver（WH-1or WH-31000ppm）. 2. Replace new solution. 3. Adopt pure water or ion exchange device to dilute water and make deionization. 4. Apply rust inhibitor on the surface of workpiece at intervals of working procedures.
5. Too low concentration	1. Only add water without supplementing stock solution. 2. Concentration supplemented and added is too low. 3. Cooling liquid deteriorates.	1. Check liquid  supplement record. Stop the doing of only adding water without supplementing stock solution. 2. Rise concentration of supplement solution. 3. Check pH value and bacteria quantity. Replace new liquid when cooling solution deteriorates. If the status of used liquid is recoverable, adjust the concentration till normal scope and add pH value improver ( WH-1, 1000ppm) and corrosion inhibitor （WB-2, 1000ppm）. 4. When processing site occurs frequently problems, it should entrust manufacturer of cutting solution to make investigation.
6. Too high concentration	1. Concentration supplemented and added is too high.	1. Adjust concentration to be lower when solution is supplemented because too much water is vaporized.
7. Foaming	1. Concentration of used cooling solution is too high. 2. Cooling solution deteriorate.  Formula balance is destroyed.	1. Adjust the use concentration of oil agent within administrative control value. Add defoamer ( WF-1,100ppm). If the water added is pure water, it should be added after mixed with water until foaming phenomenon is controlled. 2. Replace liquid.
8. Aluminum part discolors.	1. The pH value is high. The concentration of the oil is too high.	1. Retest pH value, and concentration. Adjust the pH value and concentration to administrative standard range. When aluminum discoloration fails to improve, add corrosion inhibitor for aluminum (WHM-20、1000ppm).
9. Produce a large amount of insoluble substance (gained soap)	1. The hardness of the diluted water is too high	1. Use deionized water
10. Generate the phenomenon that the paint falls off.	1. Not use  the paint with water-soluble resistance and alkali-soluble resistance. 2.The concentration of the oil used is too high.	1. Replace the paint. 2. Reduce the concentration. 3. No paint is painted on inner surface of cooling solution box.
11. Generate skin allergy	1. The operator doesn’t wear the protective gloves 2.The concentration is too high, pH value is too high	1. Please wear lab protective supplies. If the operator frequently comes in contact with cutting liquid, please use hand cream after work The work position of people with allergic skin should be replaced, and also the production line using oil-based and water-based cutting liquid at the same time shall be adjusted. 2.Adjust the pH value and concentration within administrative standard range.