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PTFE resin is mostly in powder form or dispersion. PTFE powder resin is a white, odorless, tasteless and non-toxic powder. When processed into products, it becomes a transparent or opaque white material, waxy, non-hydrophilic, smooth and non-sticky, and looks like polyethylene. Its density is as high as 2.14g/m3, making it the heaviest plastic. There are three main categories of polytetrafluoroethylene: suspension resin, dispersion resin and concentrated dispersion. In my country, suspension resin accounts for approximately 66.81% and dispersion resin accounts for 31.19%. 4.1 Application of suspension polytetrafluoroethylene Suspension PTFE is mainly used to manufacture sealing rings, gaskets, etc. for the machinery industry, as well as pumps, valves, pipe fittings, and equipment linings for chemical equipment. It also manufactures electrical insulation parts, films, etc. Suspension PTFE is generally divided into the following three categories: (1) Micro powder: The average diameter of the particles is 20~35μm, which can be molded. (2) Granulating materials: It has good powder flowability and large apparent density. Coarse particles (particle size about 300 μm) are used for automatic molding and hydraulic molding, and can also be used for general molding. (3) Pre-sintered material: The plunger method can be used to process finer and thinner products. Such as rods with a diameter of 5~50mm, pipes with a wall thickness of 3~25mm, etc. In addition, the suspension method PTFE can also be processed into ultra-fine-grained powder with a fineness of less than 10 μm. DLX-6000 from DuPont Mitsui Fluorochemicals Co., Ltd. and L-168, L-169, L-170 and L-171 from Asahi Glass Co., Ltd. are such products. Their main use is as dry powder lubricants. Currently, this type of resin is increasingly expanding its application scope as its properties are continuously improved and improved. 4.2 Application of dispersion polytetrafluoroethylene Dispersion method PTFE is mainly used to manufacture corrosion-resistant, high-temperature-resistant, high-dielectric wires and cables. In the chemical industry, it is mainly used to manufacture threaded sealing tapes, pipe linings, etc. (1) High compression ratio powder: Extrusion molding under the condition of compression ratio greater than 2500:1, suitable for processing into thin-walled thin tubes and wire insulation sheaths with a diameter of less than 2mm and a wall thickness of 0.2~0.5mm. (2) Medium compression ratio powder: Extruded under the condition that the compression ratio is greater than 400:1, it is suitable for processing into medium-sized thin-walled tubes with a diameter of 2 to 15mm and a wall thickness of 0.5mm or more. (3) Low compression ratio powder: It is extruded under the condition that the compression ratio is less than 300:1, and is suitable for processing into thicker pipes and thick bars with a diameter of more than 5mm for making sealing raw material belts. 4.3 Application of PTFE concentrated dispersion PTFE concentrated dispersion is mainly used as anti-stick coating and impregnated glass cloth, asbestos, etc. in the food, textile, printing and dyeing, papermaking and other industries. In addition, it can also be used for fiberglass and porous materials. 4.4 Overview of classification of polytetrafluoroethylene products (1) Polytetrafluoroethylene pipes: can produce micro thin-walled capillary tubes, push tubes, plunger extrusion tubes, etc. At present, the maximum diameter of domestic plunger extrusion pipe is 320mm, and the length is 4 to 6m. (2) Polytetrafluoroethylene sheet: The maximum area of the molded sheet can reach 1.2×1.2m2. Turning plate: turning with isobaric forming blank, the plate width can be up to 2m, using molding forming blank, the plate width is 1.5m. (3) PTFE rods: various general-purpose rods can be produced. The length of molded rods can reach 1.5m, isobaric molding can reach 2m, and plunger extrusion can reach 4~6m. (4) Polytetrafluoroethylene film: PTFE film includes oriented film, non-oriented film, and semi-oriented film. At present, the widest domestic film can reach 600mm. (5) PTFE-impregnated glass cloth: Due to limitations of the base material (glass cloth) and equipment, PTFE-impregnated glass cloth can currently only produce products with a width of 1.5m. At the same time, PTFE-impregnated glass cloth that can be bonded can also be produced. (6) Expanded PTFE rib sealing tape: PTFE rib sealing tape has a thickness of 0.075~0.1mm and a width of 13, 22, 26, 52mm and other specifications. Many domestic units can produce it and export it in large quantities. (7) Biaxially stretched PTFE microporous membrane and its composite materials: PTFE microporous membrane can be used as a filter material for the filtration of ultra-pure reagents, with a pore size of 0.1 to 1 μm; it can also be combined with fabric to make high-grade waterproof and breathable membranes. Clothing fabrics and high temperature resistant filter materials. The composite material width is up to 2m. (8) Expanded PTFE sealing tape, packing, and filler rods: used as sealing materials in chemical anti-corrosion and other aspects. The operating temperature is -218~320℃; among them, the thickness of the sealing tape is 0.5~5mm, and the maximum width is 80mm. The diameter of the filler rod is 1~25mm. (9) Polytetrafluoroethylene fiber: Fabrics made of PTFE fiber are used as filter materials abroad, and PTFE fiber and fabric samples are available in China. (10) Polytetrafluoroethylene filled modified products: In order to improve the creep characteristics and wear resistance of PTFE, PTFE is filled and modified. The main materials include graphite, carbon black, molybdenum disulfide, glass fiber, carbon fiber, polyethylene Phenyl sulfide etc. (11) Polytetrafluoroethylene corrugated pipes and reinforced pipes: corrugated pipes and fiber or steel wire braided reinforced hoses made by secondary processing, with high and low temperature resistance, pressure resistance, anti-corrosion, non-stick and long service life, etc. Features. Suitable for hose connections for hydraulic, pneumatic, steam delivery, etc. (12) Fluorine-containing plastic coating and plating: 1. Fluorine-containing plastic coating: Fluorine-containing plastic coating has many characteristics of fluorine-containing plastic, mainly including anti-stick coating, anti-corrosion coating, sound insulating coating, noise reduction, hydrophobic and oleophobic coating. Widely used in aerospace, aviation, papermaking, petrochemical industry, light industrial machinery, medical and health care, food machinery, ships, etc. 2. Fluorine-containing plastic electroless plating: PTFE particles are plated onto the surface of the metal substrate during the nickel plating process through electroless plating. The thickness of the coating is 5 to 25 μm, and the surface hardness (HV) is 150 to 150 for untreated ones. 250; after heat treatment, it is 300~400. The coating does not fall off or peel off, is self-lubricating, and has a friction coefficient below 0.25. 4.5 Application fields of polytetrafluoroethylene PTFE is the heaviest type of plastic. It has a wide operating temperature range (-250~260℃), good chemical stability, excellent dielectric properties, self-lubricating and anti-sticking properties, so it has a wide range of applications. In the chemical industry, it can be used as anti-corrosion materials and can be used to manufacture various anti-corrosion parts, such as pipes, valves, pumps and pipe fittings, etc. In terms of chemical equipment, it can produce linings and coatings for reactors, distillation towers and anti-corrosion equipment. Mechanically, it can be used as self-lubricating bearings, piston rings, oil seals and sealing rings, etc. Self-lubricating properties can reduce wear and heat of machine parts and reduce power consumption. In terms of electronic appliances, it is mainly used to manufacture various wires and cables, battery electrodes, battery separators, printed circuit boards, etc. Among medical materials, it can be used as a material for various medical devices and artificial organs by taking advantage of its heat-resistant, water-resistant, and non-toxic properties. The former include sterile filters, beakers, and artificial heart and lung devices, while the latter include artificial blood vessels, hearts, and esophagus. Compared with other plastics, PTFE is chemically resistant and has been widely used as sealing and filling materials. PTFE is used as engineering plastics and can be made into PTFE tubes, rods, strips, plates, films, etc. It is generally used in corrosion-resistant pipes, containers, pumps, valves, radars, high-frequency communication equipment, radio equipment, etc. that require high performance. The dispersion can be used as an insulating impregnation liquid for various materials and as an anti-corrosion coating on the surfaces of metal, glass, and ceramics. Various PTFE rings, PTFE gaskets, PTFE packing, etc. are widely used in various types of anti-corrosion pipeline flange seals. In addition, it can also be used for spinning polytetrafluoroethylene fiber - fluoronon (foreign trade name is Teflon). At present, various types of PTFE products have played a decisive role in the national economic fields such as chemical industry, machinery, electronics, electrical appliances, military industry, aerospace, environmental protection and bridges.

Classification of common seals  Common seals are divided into four categories: sealants, packing seals, rubber seals, and mechanical seals. Sealant classification: glass glue, waterproof sealant, steel barrel sealant, elastic sealant, polyurethane sealant, polyvinyl chloride clay, polysulfide sealant, acrylic sealant, flame retardant sealant, epoxy sealant, nitrile Sealant etc.  Packing seal classification: packing, metal wound gasket, graphite composite gasket, toothed gasket, octagonal gasket, steel gasket, asbestos gasket, non-asbestos gasket, flexible graphite sheet, graphite coil, graphite gasket, asbestos rope, oil-resistant Plate, filled modified PTFE sheet, PTFE sheet, etc.  Rubber seal classification: U-ring, Y-ring, O-ring, rubber sealing gasket, combination gasket, rubber diaphragm, rubber plate, nylon plate, nylon rod, rubber tube, rubber sealing strip, etc.  Gasket classification: nitrile rubber gasket, fluoroprene rubber gasket, silicone rubber gasket, fluorine rubber gasket, polyurethane gasket, polytetrafluoroethylene gasket.Classified by spare parts: sealing rings, hydraulic oil seals, coated gaskets, metal ring gaskets, alloy rings, and shaft sleeves.According to whether the spring element is rotating or stationary, it can be divided into: rotary type with internal flow unbalanced single-end seal, referred to as rotary type; stationary type with external internal flow balanced single-end seal, referred to as static type.According to whether the static ring is located inside or outside the sealing end face, it can be divided into: internal type and external type.According to the leakage direction of the sealing medium, it can be divided into: internal leakage type and external flow type.According to the unloading situation caused by the medium on the end face, it can be divided into: balanced type and unbalanced type.According to the logarithm of the sealing end face, it can be divided into: single end face and double end face.According to the number of springs, it can be divided into: single spring type and multi-spring type.Classified by elastic elements: spring compression type and bellows type.According to the non-contact mechanical seal structure classification: hydrostatic type, hydrodynamic pressure type, dry gas seal type.Classification according to sealing cavity temperature: high, medium, normal and low temperature sealing.Separated according to seal chamber pressure: ultra-high, high, medium and low pressure mechanical seals.Classification of seals The factors that affect the performance of various seals are different. For example, the influencing factors of mechanical seals (packing seals, etc.) include temperature, medium, wear, pressure, etc.According to different uses, seals are roughly classified as follows:  1. Classified by function: divided into shaft seals, hole seals, dust-proof seals, guide rings, fixed seals, rotary seals; 2. Classified by material: divided into rubber, polyurethane, engineering plastics, etc.  O-ring: Generally used as a static seal. If the working pressure exceeds 20MPa, it is generally necessary to add a back-up ring of PTFE material.2. Hole seals: Common ones include V-shaped rings, U-shaped rings, Grain rings, combined sealing rings, etc.      V-shaped ring for hole Glay ring for hole      U-shaped ring for hole combined sealing ringV-shaped rings are generally used in heavy-duty hydraulic cylinders, which have reliable sealing and generally need to be installed in pairs back-to-back with open grooves. The guide elements of this type of sealing ring generally use copper sleeves. (See below)U-shaped rings are the most widely used, and many engineering oil cylinders and water conservancy oil cylinders use this sealing type. Sealing is reliable. Open grooves or closed grooves can be used, and many of the guide elements use guide belts. (See below)Grain rings are generally used in situations where internal leakage requirements are not too high, because the material of this sealing ring sealing slip ring is mostly made of PTFE + 40% copper powder. This material has a larger internal leakage value under low pressure, and the higher the pressure, the greater the internal leakage value. The higher the sealing effect, the better. Servo cylinders generally use this type of sealing ring. Most of its guide elements use guide belts. (See below)There are many types of combined sealing rings. Many manufacturers imitate the DAS sealing rings of Baosexiaban Company. They are generally used in oil cylinders with compact structure and size. This sealing ring has a guide element and is used in this sealing ring. Afterwards, no further guide elements can be added.3. Shaft seal: Common ones include V-shaped rings, U-shaped rings, Stern seals, etc.4. Dust-proof ring: Common ones include double-acting dust-proof ring and single-acting dust-proof ring.   Stefen U-shaped ringV-shaped ringDouble-action dust ring (usually made of polyurethane material)  It is also a double-acting dust ring (combined type). The O-ring material is Buna N rubber, and the sealing ring material is generally PTFE+40% copper powder.   This is a very common single-acting dust ring, used in general occasions.   This is a dust ring with a frame. PARKER has an AF frame dust ring, which is used in extremely harsh environments.Special seal: This kind of sealing ring is widely used. It is generally used as the first seal (i.e. main seal) in the piston rod sealing system. This sealing ring has oil return properties (i.e. the leaked oil can be brought back when the piston rod retracts. Come back) very well. (Generally, it needs to be used in combination with other sealing rings)U-shaped ring: This kind of sealing ring can be used alone when the system working pressure does not exceed 20MPa. If it is used alone when the system working pressure exceeds 20MPa, it is generally necessary to add a back-up ring. It can also be used as a secondary seal, and a special seal is used in front as the main seal.V-ring: Its usage is similar to that of V-ring for holes. It needs to use an open groove, and the guide element generally uses a copper sleeve.Dust-proof ring: There are two main points to pay attention to when choosing a dust-proof ring. One is to choose according to the selection of shaft seal, and the other is to choose according to the working environment.There are several common piston rod sealing combinations:A． Ste seal + U-shaped ring + single-acting dust ringMost hydraulic cylinder piston rod seals use this type of seal.B. V-shaped ring + dust ringMost of them are used in heavy-duty hydraulic cylinders and are used in combination with V-rings for EK-type holes.C. Special seal + Special seal + double-action dust ringThere are also a wide range of applications, but most of them are used in hydraulic cylinders that require low friction resistance and fast running speed.TAG: Classification of seals

The sealing skeleton oil seal of the rotating shaft generally consists of three parts: oil seal body, reinforced skeleton and self-tightening coil spring. The sealing body is divided into bottom, waist, cutting edge and sealing lip according to different parts. The skeleton is like the steel bars inside the concrete components, which strengthens and enables the oil seal to maintain its shape and tension. Usually, the inner diameter of the skeleton oil seal in the free state is smaller than the shaft diameter, that is, it has a certain "interference". Therefore, when the oil seal is installed on the oil seal seat and the shaft, the pressure of the oil seal cutting edge and the shrinkage force of the self-tightening coil spring produce a certain radial tightening force on the shaft. After a period of operation, the pressure will quickly reduce or even disappear. , therefore, adding a spring can compensate for the self-tightening force of the oil seal at any time. Brief description: Brand: J type without skeleton Model: GJF/GJFR Oil seal Usage: Other materials: rubber Applicable models: bearings, rollers, others Working temperature: 250℃ Detailed introduction: 1. Standard Busak+Shamban TRJ type TRL type CFW—Simmerring R35 type R37 type 2. Features: Mainly used in the transmission part of rolling mills and heavy machinery. The oil seal has an outer shoulder reinforced with cloth. It is tightly integrated with the rubber sealing lip, and a spring is used to preload the sealing lip. 3. Materials: Use nitrile rubber + nitrile rubber cloth for temperatures below 100°C, and fluorine rubber + fluorine rubber cloth for temperatures below 200°C. 4. Performance* The outer edge of the oil seal reinforced with cloth is reliable and strong * The sealing lip is highly wear-resistant * The radial contact pressure of the sealing lip is durable *Good sealing effect 5. Application* Steel mill rolling mills (POMINI, DANIELI and other imported rolling mills) * Shipbuilding industry * Wind power generation equipment * Grinding machines Product use: used for sealing of rotating shafts Material: nitrile rubber Product hardness: 80±5°A Working pressure: ≤0.03Mpa Working temperature: -40~+120℃ Standard source: HG4-338-66 The skeleton oil seal structure consists of three parts: oil seal body, reinforced skeleton and self-tightening coil spring. The sealing body is divided into bottom, waist, cutting edge and sealing lip according to different parts. Usually, the inner diameter of the skeleton oil seal in the free state is smaller than the shaft diameter, that is, it has a certain "interference".

There are many kinds of sealing rings. Below, Damenson Sealing will introduce to you how to choose O-rings.        How to choose O-ring? Cylinder is a widely used actuator in pneumatic systems. According to different usage conditions, its structure and shape also come in many forms. Commonly used classification methods are as follows:1. Select the O-ring according to the direction of the force exerted by the compressed air on the piston end face. (1) Single-acting cylinder: The movement of the cylinder in only one direction is driven by air pressure, and the piston is reset by spring force or self-weight and other external forces. (2) Double-acting cylinder: The reciprocating motion of the double-acting cylinder is entirely accomplished by compressed air. 2. Select O-rings according to the structural characteristics of the cylinder (1) Piston cylinder O-ring (2) Diaphragm cylinder O-ring (3) Telescopic cylinder O-ring 3. Select the O-ring according to the installation form of the cylinder. (1) Fixed cylinder: The cylinder is installed fixedly on the body, including ear seat type, flange type and flange type. (2) Pivot-pin cylinder: The cylinder body can swing at a certain angle around a fixed axis. (3) Rotary cylinder: The cylinder is fixed on the machine tool spindle and can rotate at high speed with the machine tool spindle. This kind of cylinder is often used in pneumatic chucks on machine tools to achieve automatic loading of workpieces (4) Embedded cylinder: the cylinder is built into the fixture body 4. Select O-ring according to the function of the cylinder (1) Ordinary cylinders: including single-acting and double-acting cylinders, commonly used in situations without special requirements (2) Buffer cylinder: One or both ends of the cylinder are equipped with buffer devices to prevent and reduce the impact on the cylinder head when the piston moves to the end point. (3) Pneumatic-liquid damping cylinder: The air cylinder and the hydraulic cylinder are connected in series, which can control the movement speed of the cylinder piston and make its speed relatively stable. (4) Swing cylinder: used in situations where the cylinder blade shaft is required to rotate around the axis within a certain angle, such as fixture rotation, valve opening and closing, etc. (5) Impact cylinder: It is a high-energy cylinder that uses the high-speed movement of the piston rod to form impact force. It can be used for stamping, cutting, etc. (6) Stepper cylinder: It is a cylinder that makes the piston rod extend to different corresponding positions according to different control signals. Working characteristics of O-rings for imported cylinders: The working characteristics of the cylinder refer to the static and dynamic characteristics such as the output force of the cylinder, the change of pressure in the cylinder, and the movement speed of the cylinder. Because they have many influencing factors, many issues are still being studied. , so only a brief introduction is given here. When using the special O-ring for imported cylinders, you must pay attention to its pressure characteristics, that is, the pressure changes in the cylinder. The cylinder is usually divided into an intake chamber and an exhaust chamber by a piston. When compressed air is input to the intake chamber, the exhaust chamber is in an exhaust state. When the force formed by the pressure difference between the two chambers just overcomes various resistance loads, the piston begins to move. When there is no load, the pressure required to start movement is only 0.02~0.05MPa. During the movement of the cylinder, the pressure in the intake chamber gradually increases to the air source, while the pressure in the exhaust chamber gradually decreases. The gas pressure in the intake and exhaust chambers changes with time, and its change curve is usually called the pressure characteristic curve of the cylinder.