PTFE, PFA, FEP, PVDF Fluoroplastic products industry experts
Analysis of the manufacturing process and sintering process of PTFE gasket
Classification:
Industry dynamics
Author:
PFA tube little sister
Source:
Dankai
Release time:
2022-11-30
Visits:
Introduction of 1. PTFE gasket
The English abbreviation of PTFE is PTFE (commonly known as "plastic king"). This material product has the characteristics of acid and alkali resistance, high temperature resistance and resistance to various organic solvents. Extremely wide application in the chemical and pharmaceutical industry
Pan, can be called the originator of the gasket world. Polytetrafluoroethylene is a polymer compound formed by polymerization of tetrafluoroethylene. It has excellent chemical stability and corrosion resistance (it is the best corrosion resistance in the world today.
One of the materials, in addition to molten metal sodium and liquid fluorine, can withstand all other chemicals, boiling in aqua regia does not change, widely used in a variety of conditions requiring anti-acid and organic solvents), sealing
High lubrication, non-stick, electrical insulation and good aging resistance, temperature resistance span (can work for a long time at a temperature of 250 ℃ to -180 ℃). It was born to solve the world's chemical, petroleum,
Many problems in areas such as pharmaceuticals. It has been widely used as a sealing material and a filling material.
PTFE as a sealing material has many applications. Because of its high corrosion resistance, stable physical properties, high and low temperature resistance, the achievement of its good sealing performance, in the petroleum, chemical, manufacturing
Pharmaceutical, electric power, steel industry has a wide range of applications. Suitable media include water, oil, acid solution, alkali solution and almost all chemical ingredients.
Figure 1: PTFE gasket Source: Dankai
Fabrication Process of PTFE Gasket
(1) raw material preparation; ingredients: pure F4 products, raw material F4 fine resin, mashed, sieved.
(2) mold preparation: wipe clean with alcohol, no rust in the mold, no attachments.
(3) Weighing, according to the formula G = PV (where G is the feeding amount, P is the density of the preform (2.18g/cm3) and V is the volume of the product).
(4) Feeding: The F4 resin is evenly distributed over the entire pressing surface.
(5) Pre-forming (pressing): Calculate the gauge pressure of the press according to the formula, and set the gauge pressure of the press. Pressing.
(6) Demoulding and trimming: Take the semi-finished product out of the mold, and trim its surface to make its surface flat and neat. Ready for molding.
(7) Sintering: Slowly put the semi-finished product into the sintering furnace, put it in an appropriate quantity, heat it up to 390 degrees for one hour, keep it warm for another hour, start cooling after forming, and after about four hours, reach
Reach the indoor temperature, carry out the finished product, and finally complete the shaping.
The application of PTFE in the sealing material is not only sealing gasket, but also can be used in packing and soft packing and so on.
Sintering process of 2. polytetrafluoroethylene
When it comes to the sintering of polytetrafluoroethylene, the first thing to look at is which variety, in general, pure polytetrafluoroethylene is divided into three types: dispersion powder obtained by emulsion polymerization, molding material obtained by suspension polymerization, and emulsion. different
The variety of sintering process is different.
1. Dispersed powder
Such powders are generally molded by paste extrusion, and after extrusion, they need to be dried and sintered to obtain products. Sintering temperature is generally controlled at 380~420 degrees, the temperature is too high PTFE will decompose to produce toxic gas
body. The sintering temperature is preceded by a drying process to remove previously added additives.
2. Molding material
Due to the internal stress of the molded parts, poor sintering control will lead to cracking, so it is generally placed for a period of time from the end of molding to sintering to release the stress.
3. Emulsion
It is roughly divided into 3 steps. First, the water is evaporated at about 100 degrees, and then the surfactant in the emulsion is taken out. The temperature is adjusted depending on the active agent. Finally about 380 degrees sintering.
Characteristics of 3. PTFE gasket wound gasket
PTFE wound gasket is a kind of semi-metal flat gasket made of V-shaped or W-shaped thin steel strip and filler PTFE spiral composite winding. By changing the material combination of the gasket, various solutions can be solved.
Chemical corrosion of the gasket by the medium.
This kind of gasket has good compression rebound performance, multi-channel sealing and certain self-tightening function, which can partially eliminate the influence of pressure, temperature change and mechanical vibration. The flange surface is not bonded, which is convenient for maintenance and replacement.
It can maintain its excellent sealing performance under high temperature, low temperature, high vacuum, impact vibration and other cyclic alternating and various harsh conditions. Suitable for temperature, pressure alternating intense sealing parts, is the pipeline,
Valves, pumps, heat exchangers, towers, manholes, hand holes and other flange joint static sealing elements.
By changing the tension of the winding steel belt, the density (hardness) of the winding gasket can be changed to meet the needs of various application parts. It is widely used in petrochemical, machinery, electric power, metallurgy, shipbuilding, medicine, etc,
Atomic energy and aerospace industries.
This article is originally created by Teflon's little sister. Welcome to pay attention and take you to grow knowledge together!
Key words:
PTFE, gasket, sintering, temperature, sealing, high and low temperature resistance, corrosion resistance, aging resistance
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