Advantages:
Good oil resistance, water resistance, solvent resistance and high pressure oil resistance.
Good compression deformation, wear resistance and elongation.
Disadvantages:
Not suitable for polar solvents, such as ketone, ozone, nitrohydrocarbon, MEK and chloroform. Used for manufacturing rubber parts, especially seals, used in oil tanks, lubricating oil tanks and fluid media such as petroleum hydraulic oil, gasoline, water, silicone grease, silicone oil, diester lubricating oil and glycol hydraulic oil. It can be said that it is the most widely used rubber seal with the lowest cost at present. (Fluorocarbon rubber) There are many types of rubber containing fluorine in the molecule according to fluorine content (that is, monomer structure). At present, the widely used hexafluororubber was first listed by DuPont under the trade name "Viton". High temperature resistance is better than silicone rubber, and it has excellent chemical resistance, resistance to most oils and solvents (except ketones and esters), weather resistance and ozone resistance; Cold resistance is poor, and the general temperature range is -20~250℃. The special formula can resist the low temperature of -40℃. Advantages:
The heat-resistant temperature is as high as 250℃
Resistant to most oils and solvents, especially all acids, aliphatic hydrocarbons, aromatic hydrocarbons and animal and vegetable oils.
Disadvantages:
Not recommended for ketones, low molecular weight esters and mixtures containing nitrates. Automobile, locomotive, diesel engine and fuel system.
Seals from chemical plants. (Silicone rubber) The main chain of silica gel is composed of silicon (-si-o-si). Excellent heat resistance, cold resistance, ozone resistance and atmospheric aging resistance. It has good electrical insulation performance. The tensile strength is worse than that of ordinary rubber, and there is no oil resistance. Advantages:
After the formulation is prepared, the tensile strength can reach 1500PSI and the tear strength can reach 88LBS.
Good elasticity and good compression deformation.
Good resistance to neutral solvents
Excellent heat resistance
Excellent cold resistance
Excellent ozone and oxidation corrosion resistance.
Excellent electrical insulation performance
Good heat insulation and heat dissipation performance
Disadvantages:
It is not recommended to use in most concentrated solvents, oils, concentrated acids and diluted sodium hydroxide. Seals or rubber parts used in household appliances industry, such as rubber parts in electric kettle, iron and microwave oven.
Seals or rubber parts in electronic industry, such as mobile phone keys, shock absorbers in DVD, and seals in cable connectors.
Seals on various articles in contact with human body, such as kettles and drinking fountains. The main chain of ethylene-propylene rubber is not double-stranded, so it has excellent heat resistance, aging resistance, ozone resistance and stability, but sulfur cannot be added. In order to solve this problem, EPDM can be obtained by introducing a small amount of the third component with double chains into the main chain of EP and adding sulfur. The general temperature range is -50~ 150℃. Excellent resistance to polar solvents, such as alcohol, ketone, ethylene glycol and phospholipid hydraulic oil.
Advantages:
Good weather resistance and ozone resistance
Excellent water resistance and chemical resistance.
Alcohol and ketones can be use.
High temperature steam resistance and good air tightness.
Disadvantages:
Not recommended for food or contact with aromatic hydrogen. Seals in high temperature water vapor environment.
Sanitary ware seals or parts.
Rubber parts in the braking system.
Seals in radiator (automobile water tank). Neoprene CR
(chloroprene rubber, polychloroprene) is polymerized from chloroprene monomer. Vulcanized rubber has good elasticity and wear resistance, is not afraid of direct sunlight, especially has good atmospheric aging resistance, strong twisting resistance, resistance to refrigerants such as dichlorodifluoromethane and ammonia, resistance to dilute acid and silicone ester lubricating oil, and resistance to phosphate ester hydraulic oil. It is easy to crystallize and harden at low temperature and has poor storage stability. It has great expansion in mineral oil with low aniline point. Generally speaking, the temperature range is -50~ 150℃
Advantages:
Good elasticity and good compression deformation.
The formula does not contain sulfur, so it is very easy to make.
It has the characteristics of animal and vegetable oil resistance.
Physical properties will not be affected by neutral chemicals, esters, oils, various oils and solvents.
It has fire-proof characteristics.
Disadvantages:
Strong acids, nitro-hydrocarbons, esters, chloroform and ketones are not recommended. R 12 refrigerant-resistant seal. Rubber parts or seals on household appliances.
Suitable for making all kinds of parts that are in direct contact with the atmosphere, sunlight and ozone.
Suitable for all kinds of fire-resistant and chemical-resistant rubber products. Hydrogenated nitrile rubber is a kind of nitrile rubber with partial double chains removed after hydrogenation. After hydrogenation, the temperature resistance and weather resistance are much higher than those of ordinary nitrile rubber, and the oil resistance is similar to that of ordinary nitrile rubber. The general temperature range is -25~ 150℃.
Advantages:
Compared with butyl rubber, it has better wear resistance.
Excellent corrosion resistance, tensile resistance, tear resistance and compression deformation.
Good resistance to ozone, sunlight and other atmospheric conditions.
Generally speaking, it is suitable for washing clothes or washing dishes.
Disadvantages:
It is not recommended to use in alcohol, esters or aromatic solutions. Air-conditioning and refrigeration industries are widely used as seals in environmental protection refrigerant R 134a system.
Automobile engine system seal. Butyl rubber is polymerized from isobutylene and a small amount of isoprene, and a small amount of unsaturated groups are reserved for sulfur addition. Because sterically hindered molecules of methyl move less than other polymers, it has less air permeability, stronger resistance to heat, sunlight and ozone, and better electrical insulation. It is resistant to polar solvents, such as alcohol, ketone, ester and so on. The general temperature range is -54~ 1 10℃.
Advantages:
Impermeability to most common gases
Good resistance to sunlight and ozone
May come into contact with animals or vegetable oils or oxidizable chemicals.
Disadvantages:
Do not use it with petroleum solvent, colloidal kerosene and aromatic hydrogen at the same time. Used for manufacturing rubber parts of chemical corrosion resistant and vacuum equipment. Fluorescent silicone rubber is fluorinated silicone rubber, and its general properties have the advantages of both fluororubber and silicone rubber. Its oil resistance, solvent resistance, fuel oil resistance and high and low temperature resistance are all good, and the general use temperature is -50~200℃.
Advantages:
Suitable for special purposes, such as corrosion resistance of oxygen-containing chemicals, aromatic hydrogen-containing solvents and chlorine-containing solvents.
Disadvantages:
Contact with brake oil, ketone, cockroach solution and space parts is not recommended. The unvulcanized O-ring compound is a viscous fluid at high temperature and high pressure, but in the molding vulcanization stage, the compound quickly fills the mold cavity, and the excess part (in order to prevent the lack of glue, the compound filled in the mold cavity must be kept in a certain amount) overflows and sulfides, thus forming overflow (also called scrap and flash). Once the overflow is formed, it must be removed to make the appearance neat and beautiful. This process is often called trimming. The requirements for trimming are accurate size and neat appearance. In actual production. Finishing products is usually time-consuming and laborious. For products with strict requirements, a little carelessness in finishing may lead to waste, so we must be cautious. Generally speaking, the smaller the product size, the more complicated the configuration, the more difficult the finishing and the more waste products.
O-ring dressing can be divided into three categories: manual, mechanical and freezing:
1。 Trim by hand. The operator holds a knife and gradually trims the overflow edge along the outer edge of the product. This is the most primitive method. The efficiency is low and the quality is difficult to guarantee, especially the O-ring with small size and high precision, which is easy to damage the connection between the product body and the overflow edge. Tooth marks and gaps are often left, thus leaving problems such as oil leakage and air leakage that affect sealing. In addition, the dependence of manual pruning on operating proficiency is also very prominent.
2. Mechanical trimming. In order to improve efficiency and quality, mechanical trimming appeared. Common is a special electric edger with rotating blades. The blade used must be highly matched with the size of the product. If the inner and outer edges of the product have overflow edges. Can be designed as double-edged and multi-edged. So as to achieve one-time completion. The machining accuracy of mechanical trimming is higher than that of manual trimming, and the efficiency is doubled. Especially for multi-cavity products, matching tools can be designed according to the arrangement and distribution of products. After the product is taken out of the mold. It can be sleeved on the whole board and punched at one time. With the help of heating, dozens can be repaired at a time. The key is to control the punching temperature to prevent sticking after it is too high. The choice of rubber O-ring hardness is more important. For example, the sealing ring with hardness of 70 (Shore) of pump turbine in a power station often peels off or even cuts off horizontally, and then the sealing ring with hardness of 85 ~ 90 (Shore) is adopted, and the effect is ideal.
Low hardness, convenient installation, but easy to peel off, installation damage, extrusion and even explosion. The hardness is too high and the installation is inconvenient.
Generally, the hardness of rubber O-rings is 40 ~ 90 IRHD, but 70 IRHD is more suitable for use, except for silicone rubber, which is generally 60 IRHD.