The main function is to reduce the friction damage of the friction surface. However, due to the wide range of industrial machinery, the requirements of various machinery for lubricating oil mainly meet the requirements of reducing friction and wear, and there are some special requirements with different working environments and working conditions. It is divided into:
(1) vehicle lubricant
(2) industrial lubricant
including machine oil (high-speed lubricant), weaving oil, spindle oil, rail oil, steel rolling oil, gas turbine oil, compressor oil, refrigeration oil, cylinder oil, marine oil, gear oil, machine gear oil, axle oil, instrument oil and vacuum pump oil
(3) common grease. When the nickel-chromium layer is destroyed, impure iron (containing carbon) is exposed to the air, and when it comes into contact with oxygen and water, it will undergo oxidation reaction, thus causing corrosion. The use of lubricant for medical surgical instruments can effectively avoid or delay the corrosion of surgical instruments. The ideal lubricant for medical surgical instruments should meet the following characteristics:
1. Water-soluble lubricant, with stable effect every time used, ensuring sterilization to effectively penetrate
1. Effectively lubricate the joint parts of instruments, making the use of instruments more flexible
1. Corrosion resistance, prolonging the service life of instruments
1. Less auxiliary additives, and reducing the residue of additives and spots on the surface of instruments
1. Does not affect the normal use of the cleaning machine
6. The components are safe and environmentally friendly
In addition, the American national standard ANSI/AAMI ST79 stipulates that mineral oil and related oils should not be used for equipment lubrication, unless the manufacturer suggests using such lubricants to lubricate the internal mechanical devices of power-driven equipment. China health industry standards stipulate that lubricants should be used for equipment maintenance, and water-insoluble products such as paraffin oil should not be used as lubricants. Lubricant can play a lubricating role because its addition reduces the friction of plastic melt, which can be divided into internal friction and external friction. Therefore, there is an inner lubricant and an outer lubricant.
1. The external lubricant is mainly used to improve the friction between the polymer melt and the hot metal surface of the equipment, so that the plastic parts can be easily demoulded. It has poor compatibility with the polymer and is easy to migrate from the melt. In the molding process, a thin isolation film can be formed between the melt and the mold, so that the plastic does not stick to the mold surface.
2. The internal lubricant has good compatibility with the polymer, which plays a role in reducing the intermolecular cohesion of the polymer, thus improving the internal friction heat generation of the plastic melt and the fluidity of the melt. The combination between internal lubricant and polymer long-chain molecules is not strong, and they may act like rolling bearings, so they can arrange themselves in the direction of melt flow, thus sliding with each other, reducing internal friction, which is the mechanism of internal lubrication. There are many kinds of lubricants, among which paraffin, stearic acid and their salts are commonly used. Internal lubricants include relatively low molecular weight PE, PTFE, PP, etc. These low molecular weight polymers are not only excellent internal lubricants, but also good external lubricants. Sometimes, the effect of one lubricant is often not ideal, and several lubricants need to be used together, thus resulting in a composite lubricant, which can play a variety of roles. The effect is better. The dosage of lubricant is generally .5%-1%.
When selecting lubricant, the following principles should be followed:
1. If the fluidity of polymer can meet the needs of molding process, it is mainly considered whether the external lubricant meets the process requirements and is easy to demould to ensure the internal and external balance.
2. Whether external lubrication is ideal depends on whether it can form a complete liquid film on the plastic surface during molding. Therefore, the melting point of external lubricant should be close to the molding temperature, but pay attention to the difference of 1-3℃, so as to form a complete film.
3. The compatibility with polymer is moderate, the internal and external lubrication functions are balanced, no frost is sprayed, and scaling is not easy.
4. The lubricant has excellent heat resistance and chemical stability, does not decompose during processing, does not volatilize, does not corrode equipment, does not pollute products and has no toxicity. Adding a small amount of additives to lubricating oil and grease can improve the performance of lubricating oil and grease, and the degree of improvement is related to the quality of base oil. Additives can be roughly divided into two categories: one is additives that affect the physical properties of lubricating oil and grease, such as pour point depressants, viscosity index improvers and defoamers; The other kind is additives that affect the chemical properties of lubricating oil and grease, such as various antioxidants, anti-corrosion agents, detergents, oiliness agents and extreme pressure and anti-wear agents. In addition, there are emulsifiers and rust inhibitors.