Oxidation of cutting oil can cause the following problems:
1) The acid value increases, corroding workpieces and machine tools.
2) Oxidation generates high polymer, which forms sludge, and adhesion and adsorption occurs on the surface of workpiece and machine tool, which hinders the operation of machine tool and blocks the circulation system.
3) Foam is generated due to oxidation, which hinders the penetration of cutting oil into the processing area, reduces its lubrication and cooling performance, and even causes overflow.
4) The high polymerization reaction occurs due to oxidation, which increases the viscosity of the cutting oil, affects its permeability and cleaning performance, and increases the loss of cutting oil because the cutting oil is easier to adhere to the chips and be taken away.
The main reasons and solutions for the deterioration of cutting oil due to oxidation reaction are as follows:
1) Oxidation occurs in contact with oxygen in the air. Cutting oils should be stored in airtight areas, avoiding contact with oxygen as much as possible.
2) Light is the inducing condition of oxidation reaction. Use and store as far away from light as possible.
3) Some metals will promote the oxidation of cutting oil, and even more metal salts in the oil. Machining debris, etc. in the cutting oil should be removed in time.
4) The selected Base Oil has poor oxidation resistance. When preparing base oils, paraffin-based base oils or aromatic hydrocarbons with good oxidation resistance should be selected as far as possible, and naphthenes with poor oxidation resistance, especially multi-branched alkanes, should be avoided; highly refined base oils should be used.
5) High temperature is easy to cause oxidation. High temperature should be avoided as much as possible during use and storage.
6) Adding antioxidants can improve the antioxidant properties. Antioxidants are mainly divided into aromatic gum antioxidants, such as octylbutyldiphenylamine (L57); hindered phenolic antioxidants, such as 2,6-di-tert-butyl-p-cresol (750) and auxiliary antioxidants agents, such as distearyl pentaerythritol diphosphite (DPD). In addition, some extreme pressure agents also have certain antioxidant properties, such as zinc dialkyldithiophosphate (ZDDP).
