PTFE Overview: Pros & Cons, Characteristics, CNC Machining PTFE

Polytetrafluoroethylene is often used in industrial products, especially under friction and sealing conditions. It’s also is a commonly used material for CNC machining due to its unique properties and versatility. Today, let’s take a closer look at what PTFE is.

What Is PTFE?

Polytetrafluoroethylene is a fluorocarbon polymer commonly abbreviated as PTFE. Teflon ® The PTFE brand is only produced by Dupont Corporation. Other manufacturers also produce their own PTFE materials. This family of fluoroplastics can provide products with high chemical resistance, high and low temperature resistance, weather resistance, low friction, electrical and thermal insulation, and “slipping”. The mechanical properties of PTFE are somewhat poor compared to other plastics, but its performance remains at a useful level in the wide temperature range of – 73 ℃ to 204 ℃. Generally, mechanical properties are increased by adding some fillers, which have excellent thermoelectric insulation properties and low coefficient of friction.

The main additives for PTFE include glass fiber, carbon, graphite, molybdenum disulfide, and bronze. Generally speaking, filled PTFE can maintain its excellent chemical and high-temperature properties, but at the same time, the filler greatly improves its mechanical strength, stability, and wear resistance. The commonly used 25% glass fiber PTFE and 25% carbon PTFE are the most commonly used.

What are the Pros and Cons of PTFE?

Pros:

– Chemical resistance: PTFE has excellent chemical resistance and can withstand exposure to many chemicals, acids, and bases.

– Low friction: PTFE has a very low coefficient of friction, making it an ideal material for use in applications where reduced friction and wear are important.

– High temperature resistance: PTFE has excellent thermal stability and can withstand temperatures up to 260°C, making it ideal for use in high-temperature applications.

– Non-stick properties: PTFE has excellent non-stick properties and is often used as a coating for cookware and bakeware.

– Electrical insulation: PTFE has excellent electrical insulation properties and is often used as an insulator in electronic applications.

Con:

– High cost: PTFE is a relatively expensive material, which can make it less cost-effective for certain applications.

– Difficult to process: PTFE is a difficult material to process due to its low melt viscosity and tendency to stick to processing equipment.

– Limited strength: PTFE has relatively low strength compared to other engineering plastics, which can limit its use in certain applications.

– Poor wear resistance: Although PTFE has low friction, it can exhibit poor wear resistance in certain applications, especially in high-load, high-speed applications.

– Environmental concerns: PTFE is a non-biodegradable material that can pose environmental concerns when disposed of improperly.

PTFE Processing and Main Applications

PTFE has a high melting point, high melting viscosity, and is sensitive to shearing in an amorphous state, which can easily lead to melt fracture. Therefore, conventional thermoplastic molding processes such as melt extrusion and injection molding cannot be used, and sintering molding can only be performed using methods similar to powder metallurgy.

The manufacturing of filled PTFE, like the molding of PTFE, can be preformed, sintered freely, or molded using plunger extrusion. The above processing processes are generally suitable for products with a certain wall thickness, but are not suitable for the processing of PTFE films. In recent years, a large amount of research has been conducted in China, and relatively mature processing technologies include calendering for dispersed PTFE resins; Utilize the characteristics of Dankai PTFE sintered products such as low hardness and good toughness to conduct metal cutting processing; In addition, there is also a conventional extrusion method and a calendering method for extrusion processing, in which the resin is directly processed without melting and plasticizing.

In addition to the primary processing process described above, there are also some newly developed secondary processing technologies that deserve attention, such as PTFE vacuum molding technology, hot press molding and hot blow molding technology, and isobaric molding processing technology. PTFE is the preferred material for corrosion resistant lining of corrosion resistant pipes, pipe fittings, corrugated pipes, pump bodies, valves, kettles, tanks, towers, and various standard equipment; As a sealing material, it is widely used in the mechanical, petrochemical, transportation, textile, and construction industries; Dankai PTFE can also be used as corrosion resistant and low friction parts for valves, bearings, piston rings, guide rails, etc.

After treatment, PTFE film has selective permeability and can be used as a separation material to selectively permeate gases or liquids, especially to filter corrosive liquids; Due to the excellent biocompatibility of polytetrafluoroethylene, many people have conducted in-depth research on it as a biomaterial in recent years. In recent years, PTFE membranes have been used as artificial organs, such as artificial blood vessels, heart valves, and so on at home and abroad. For example, in clinical applications, it has been used as a prosthetic stent material for artificial blood vessels and nasal plastic surgery, and has achieved good results.

PTFE for CNC Machining

Here are some key considerations for CNC machining PTFE:

– Cutting tools: PTFE is a relatively soft material, so cutting tools with sharp edges, low helix angles, and high relief angles are recommended for CNC machining. Carbide cutting tools are often used due to their durability.

– Cutting speeds and feeds: PTFE requires slower cutting speeds and feeds compared to other materials to avoid melting or sticking to the cutting tool. Cutting speeds of around 200-300 RPM and feeds of 0.002-0.003 inches per revolution are recommended.

– Cooling and lubrication: PTFE generates heat during cutting, so cooling and lubrication are important to prevent overheating and sticking. Coolants such as air, water, or oil can be used to keep the cutting tool and the material cool.

– Machining operations: CNC machining can be used for a variety of PTFE machining operations, including drilling, milling, turning, and threading.

– Surface finish: PTFE has a naturally smooth surface, but further polishing or buffing may be required to achieve a desired surface finish.

– Cleanliness: PTFE is prone to picking up contaminants, so it’s important to keep the material and the machining equipment clean during CNC machining.

PTFE Overview: Pros & Cons, Characteristics, CNC Machining PTFE

What Is PTFE?

What are the Pros and Cons of PTFE?

PTFE Processing and Main Applications

PTFE for CNC Machining

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