Generally, the corrosion problems encountered in the process of metal processing can be divided into two situations: the rust of machine tools after long-term use and the rust of metal products after processing. The metal processing oil should solve the corrosion problems in two aspects: to prevent the corrosion of metal objects to be processed and to prevent the corrosion of machine parts (metal parts that complete processing tasks). There are four kinds of metals that are most common in industry: steel, aluminum, magnesium and titanium. Now we will introduce the common metal processing corrosion problems, hoping to help you.
In addition to the components of the metal processing oil itself, the factors affecting corrosion include moisture / humidity, temperature, air quality, whether the oil is polluted (acids, salts, other liquids such as chemical liquids, other oils, etc.), bacteria, etc., which will lead to uneven concentration of different areas of the metal surface, cracks and gaps on the metal surface, or galvanic corrosion between dissimilar metals.
Iron and steel are the most common metals with low price and high strength. The disadvantage is that they are easy to corrode (rust). Corrosion inhibitors commonly used in metal processing oil include amine compounds. Amines are key to rust prevention. Pay attention to the content of amines during testing. In actual use, the factors affecting this performance include poor water quality, high bacterial content, high humidity, acid in the air, etc.
Solution: the use of oil-based cutting oil can prevent the occurrence of steel rust on the premise of ensuring the processing quality.
The density of aluminum is only about 1/3 of that of iron, which has the advantage that it is not easy to corrode. However, in some cases, aluminum will corrode, such as contact with some metal salts (such as chlorides), high pH value, and contact with other metals to form galvanic corrosion. The common corrosion inhibitors of aluminum metal processing oil include silicate, phosphate ester, etc.
Solution: using vulcanized lard as the main extreme pressure additive and reducing the proportion of chlorinated paraffin can effectively prevent aluminum corrosion.
Magnesium is less dense than aluminum (2/3 of aluminum), but has better strength. Magnesium has two disadvantages: it is flammable and chemically active. It will react with water to generate hydrogen, which is flammable and explosive. This is particularly important when using water-based process fluids.
Solution: metal processing oil can be used to react with magnesium sheet, and the volume of hydrogen generated can be collected and measured to judge the reaction strength between metal processing oil and magnesium. In addition, attention should be paid to the corrosion degree of magnesium sheet.
Titanium has the advantages of low density, high strength, the highest strength to weight ratio and corrosion resistance. But the thermal conductivity is poor, so the heat dissipation capacity is not good. In processing and cutting, heat is easy to concentrate on the cutting surface and contact surface. The elasticity of titanium metal is very good, which means that during processing, titanium material is easy to bounce off and deviate when it is stressed, unless the stress is large during processing. Titanium is corrosion resistant, but it is prone to stress corrosion and cracking at high temperature.
Solution: special precision cutting oil for processing titanium alloy can be used to provide excellent extreme pressure and anti-wear performance and ensure product quality on the premise of protecting machine tool equipment.
(Note: part of the article comes from the Internet)
