Guide to selecting plastic sealing materials

The selection of suitable sealing materials is a decisive factor for the efficiency and longevity of technical systems. Plastic seals are used in a wide variety of applications – from the food industry through medical technology to the chemical industry. But which factors determine which material is suitable for a particular seal? This guide provides comprehensive orientation when selecting the right plastic for seals.

Requirements for plastic seals

Plastic seals must meet a wide range of requirements, which can vary greatly depending on the area of application. Media resistance, temperature tolerance, mechanical load-bearing capacity and regulatory approvals are just some of the decisive criteria. Depending on the industry, the materials must, for example, be resistant to aggressive chemicals or approved for contact with food.

Common plastics for seals

The following table provides an overview of common plastics used for seals, including their typical properties:

Plastic	Properties	Typical areas of application
PTFE (Teflon)	Very good chemical resistance, high temp. tolerance	Chemicals, pharmaceuticals, food industry
PEEK	High mechanical strength, resistant to high temperatures	Aviation, mechanical engineering, medical technology
PVDF	Good resistance to acids and alkalis	Chemical plants, semiconductor manufacturing
UHMW-PE	Very abrasion-resistant, good sliding properties	Conveyor technology, food industry
PA (polyamide)	Robust, good mechanical properties	Mechanical engineering, automotive industry
FKM (fluoro rubber, e.g. Viton)	Excellent media and temperature resistance	Oil and gas applications, hydraulic systems

Selection criteria in detail

The selection of the suitable plastic depends largely on the specific conditions of the application. The following aspects should be taken into account:

• Operating temperature: Plastic seals behave differently at different temperatures. While PTFE withstands temperatures of over 250 °C, PE, for example, can only be used up to approx. 80 °C.
• Chemical environment: Resistance to media such as acids, alkalis, oils or solvents is critical. PTFE and PVDF show excellent properties here.
• Mechanical load: Under high pressure loads or heavy movement, PEEK or PA are required, as they offer high strength and dimensional stability.
• Regulatory requirements: In sensitive areas such as food or medical technology, certified materials such as PTFE or certain PEEK variants must be used.

Advantages of plastic seals

Plastic seals offer a wide range of advantages over metallic or elastomeric alternatives:

• Low weight
• Freedom from corrosion
• Good sliding properties
• Long service life
• Versatile processing options (e.g. CNC milling, injection moulding)

Typical areas of application

Plastic seals are indispensable in modern industrial applications. In chemical plants, they impress with their resistance to aggressive media. In food processing, hygienic, easy-to-clean materials are required. Medical technology benefits from biocompatible materials that withstand sterile environments. And in mechanical engineering, robust seals are needed that function reliably even with moving parts and in hydraulic systems.

Conclusion

Selecting the right plastic seals is a demanding task that requires technical know-how and a deep understanding of the operating conditions. Factors such as temperature, chemical contact, mechanical load and legal requirements must be carefully examined. Only the right choice of material can minimise downtime and increase efficiency.

Anyone who asks the right questions and relies on proven materials benefits in the long term from reliable and durable sealing solutions.