Silicone vs. PTFE: A comparison as a sealing material

In the world of sealing materials, silicone and PTFE (polytetrafluoroethylene) play an important role. Both materials offer unique properties that make them suitable for different applications. This article examines the differences and similarities between silicone and PTFE as sealing materials and highlights their areas of application, processing and technical differences. It is important to emphasize that this article is not about the use of PTFE spray or silicone spray, but only about the solid sealing materials.

Applications of silicone and PTFE as sealing materials

Silicone as a sealing material

Silicone is a versatile material used in many sealing applications due to its flexibility and resistance to extreme temperatures and environmental conditions. Typical applications of silicone seals include:

• Automotive industry: seals in engines and transmissions
• Medical Devices: Seals in medical devices and instruments
• Food industry: seals in processing plants and packaging
• Electronics: Seals in housings of electronic devices

PTFE as sealing material

PTFE, known by the brand name Teflon, is used in numerous sealing applications because of its excellent chemical resistance and low coefficient of friction. Typical applications of PTFE seals include:

• Chemical industry: Seals in pipelines and containers for aggressive chemicals
• Aerospace: Seals in fuel and hydraulic systems
• Food and pharmaceutical industries: Seals in systems that must meet strict hygienic requirements
• General mechanical engineering: Seals in pumps and valves

Technical differences between silicone and PTFE

Ttemperature resistance

Silicone: Silicone seals are known for their excellent temperature resistance. They can be used in a wide temperature range from around -60°C to +200°C, with some special silicones even being able to withstand temperatures up to +300°C.
PTFE: PTFE seals also offer excellent temperature resistance and can be used in a temperature range of -200°C to +260°C. This makes PTFE ideal for applications in extreme temperature environments.

Chemical resistance

Silicone: Silicone offers good resistance to many chemicals, but is susceptible to certain solvents and acids.
PTFE: PTFE is virtually inert to almost all chemicals, including strong acids and bases. This exceptional chemical resistance makes PTFE ideal for use in aggressive chemical environments.

Mechanical properties

Silicone: Silicone seals are characterized by their flexibility and elasticity. They have good tensile strength and extensibility, making them ideal for applications where good conformance to surfaces is required.
PTFE: PTFE gaskets are less elastic than silicone gaskets, but offer extremely low friction and are highly abrasion resistant. These properties make PTFE suitable for applications where low friction and high abrasion resistance are required.

workability

Silicone: Silicone is easy to process and shape. It can be extruded, injected and cast in various shapes. This versatility in processing enables the production of seals in complex geometries.

PTFE: PTFE is more difficult to process than silicone. It cannot simply be molded or cast, but is usually given the desired shape by mechanical processing, such as turning or milling. This can increase manufacturing costs but provides precise control over seal geometry.

Applications and processing

silicone seals

Silicone gaskets are often used in applications that require flexibility, elasticity and resistance to extreme temperatures. They are easy to make in different shapes and sizes, making them versatile. Silicone seals are often manufactured by extrusion or injection molding, allowing for cost-effective production.

PTFE seals

PTFE seals are ideal for applications requiring excellent chemical resistance and low friction. PTFE is often used in the form of sealing tapes, gaskets and custom gaskets. Processing PTFE requires specialized techniques such as CNC machining to produce precise and customized seals.

Both silicone and PTFE offer unique advantages as sealing materials. Silicone scores with its flexibility, temperature resistance and ease of processing, while PTFE impresses with its exceptional chemical resistance and low friction. The choice of the appropriate material depends largely on the specific requirements of the application. By understanding the technical differences and applications of both materials, engineers and manufacturers can make the best possible decision for their sealing applications.