Polyimide (PI) is the highest-performance material in the engineering plastics range. It is specified where PEEK and PEI reach their thermal or tribological limits and where a single component must combine high-temperature stability, wear resistance and electrical insulation.
With an operational temperature range from -269 degrees C to +400 degrees C, PI covers conditions from deep cryogenic environments to extreme high-temperature processes. Where PEEK operates up to approximately 250 degrees C and PEI up to approximately 170 degrees C, Polyimide continues to perform reliably above both, because the polyimide backbone has one of the highest thermal stabilities of any organic material.
This article explains when to choose PI over PEEK or PEI, the advantages of the material, the available grades, typical machined Polyimide components and the stock forms supplied by Plastix Factory.
When Should You Choose Polyimide Instead of PEEK or PEI?
PEEK and PEI cover most high-performance requirements at lower cost and with broader stock availability. Polyimide becomes the better choice when the application exceeds what these materials can deliver. As a high temperature plastic, PI is typically specified in the following cases:
- Continuous service temperature above approximately 250 degrees C, beyond the practical limit of PEEK.
- High-temperature tribological contact, dry-running, vacuum or oxygen-free environments, where filled PI grades operate without external lubrication.
- Low outgassing and dimensional stability at extreme temperature, for example in semiconductor and aerospace equipment.
- A single part that must span cryogenic to high-temperature conditions.
Conversely, PEEK remains the more economical choice up to approximately 250 degrees C where maximum mechanical strength, chemical resistance and large stock shapes are required. PEI is preferred for cost-sensitive dielectric and structural parts operating up to approximately 170 degrees C.
The table below positions the three materials objectively for material selection.
| Property | Polyimide (PI) | PEEK | PEI |
|---|---|---|---|
| Continuous operating temperature | Up to approx. 300 degrees C, short-term peaks toward 400 degrees C | Up to approx. 250 degrees C | Up to approx. 170 degrees C |
| Mechanical performance | Good; properties retained at very high temperature; more brittle | Very high strength and load-bearing, especially in reinforced grades | High strength and stiffness; amorphous |
| Electrical insulation | Excellent; stable across the full temperature range | Good | Excellent dielectric properties |
| Wear resistance | Excellent in filled grades, including dry-running and high-temperature contact | Very good, especially in tribological grades | Moderate |
| Typical applications | Semiconductor, aerospace, high-temperature bearings, dry-running parts | Structural, chemical, medical and general engineering parts | Electrical, structural and cost-sensitive engineering parts |
Note: values are indicative and depend on grade, load and environment. Confirm requirements against the relevant material data sheet.
What Is Polyimide (PI)?
Polyimide (PI) is a super engineering plastic used where an exceptional combination of thermal stability, wear resistance and electrical insulation is required across extreme operating conditions. As a PI material, it defines the upper end of the engineering plastics range.
Its defining characteristics include:
- Widest thermal operating range in the portfolio, from -269 degrees C to +400 degrees C
- Outstanding wear resistance under sustained friction contact
- Stable and predictable friction behaviour across operating conditions
- Excellent dielectric performance maintained across the full temperature range
- Inherent flame retardancy without additives
- Good machinability by CNC turning, milling and drilling to precise tolerances
Key Advantages of Polyimide
Exceptional thermal stability
Polyimide operates continuously across the widest thermal range in the portfolio, from cryogenic conditions at -269 degrees C to high-temperature processes toward +400 degrees C. It retains its mechanical and dimensional properties at temperatures where most engineering plastics can no longer be used, which is why it is chosen as a high temperature plastic for critical parts.
Outstanding wear resistance
Polyimide is a wear resistant plastic under sustained friction contact. Filled grades are engineered for tribological applications and provide long service life in bearings, bushings and sliding elements.
Stable friction level
Polyimide maintains a consistent and predictable friction level across changing operating conditions, which is critical for precision mechanical components across their full temperature and load range.
Excellent electrical insulation
Polyimide is a high-specification electrical insulation material with dielectric performance that is maintained across the full temperature range, suitable for demanding electronic and electrical environments.
Inherent flame retardancy
Polyimide is inherently flame retardant without flame-retardant additives, which suits aerospace and electronics environments with strict fire safety requirements.
Good processability
Machined Polyimide can be produced by CNC turning, milling and drilling to precise tolerances, which allows small, high-value components with tight dimensional requirements.
Internal link: anchor “CNC machining / finished parts” -> /products/ (link to a dedicated CNC machining page if available, otherwise Products)
Polyimide Grades
Polyimide is available in five variants. Each grade is engineered for a specific set of tribological, electrical or environmental requirements.
Polyimide N (Natural)
Unfilled base grade with the highest purity. Excellent electrical insulation and outstanding chemical resistance for high-purity electrical and structural applications.
Polyimide G15
15 percent graphite-filled grade with self-lubricating properties. Good wear and friction behaviour for dynamic components under sustained contact.
Polyimide G40
40 percent graphite-filled grade engineered for maximum dimensional stability and ultra-low thermal expansion, where tight dimensional control must be held across a wide temperature range.
Polyimide MoS
15 percent molybdenum disulfide (MoS2) filled grade for dry-running applications in vacuum and oxygen-free environments, where lubrication is not possible or not permitted.
Polyimide ESD
Electrostatic dissipative grade with controlled surface resistivity, specified for semiconductor and LCD applications requiring electrostatic control alongside thermal and dimensional stability.
Where Polyimide Is Used
Polyimide is applied where the required combination of thermal stability, wear resistance and electrical performance cannot be achieved with standard engineering plastics.
Electronics and electrical engineering
Insulating components, carrier plates, precision housings and structural parts requiring stable dielectric performance at extreme temperatures. The ESD grade provides controlled surface resistivity.
Aerospace and aviation
As an aerospace plastic, Polyimide is used for structural and functional components requiring lightweight construction, high-temperature performance, flame retardancy and dimensional stability under combined thermal and mechanical stress.
Semiconductor manufacturing
As a semiconductor plastic, PI is used in fabrication equipment, wafer handling, test sockets and precision components where chemical resistance, dimensional precision, thermal stability and electrostatic control are all critical.
Automotive
High-temperature under-bonnet components, transmission parts and engine-adjacent elements where sustained elevated temperatures and wear resistance exceed standard engineering plastics.
Medical devices
Precision device components, instrument parts and structural elements requiring sterilization resistance and dimensional precision in miniature high-performance applications.
Machinery and heavy industry
Precision bearing elements, thrust washers, wear rings and sliding components combining dry-running capability, high load and extreme temperatures. The graphite and MoS grades are specified for these applications.
Typical Polyimide Components
Because machined Polyimide holds tight tolerances and retains its properties at temperature, it is specified for small, high-value functional parts, including:
- Bearing bushings for high-temperature and dry-running service
- Thrust washers under combined load and temperature
- Wear rings and sliding elements in precision assemblies
- Insulating rings and dielectric components for electrical assemblies
- Semiconductor fixtures for wafer handling and process equipment
- Test sockets requiring dimensional precision and electrostatic control
- Aerospace components requiring flame retardancy and thermal stability
- Precision machined parts to customer drawings
Available Forms
Plastix Factory supplies Polyimide in precision stock shapes and CNC-machined finished parts across all five grades.
- Polyimide sheets in precision format 360 x 320 mm, thicknesses from 1 to 50 mm across nine standard thicknesses
- Polyimide rods (round bars) from 2 to 85 mm diameter in 1000 mm lengths
- Cut-to-size from standard sheet or bar stock
- CNC-machined finished parts to technical drawings, including bearing bushings, thrust washers, seals and insulating rings
Available grades: Polyimide N (Natural), G15, G40, MoS and ESD.
Why Plastix Factory?
Customers source Polyimide from Plastix Factory because material selection, stock and machining are handled in one place:
- Five Polyimide grades covering electrical, tribological, dimensional and electrostatic requirements
- Polyimide sheets and round bars from standard stock
- Cut-to-size service to exact dimensions
- CNC machining of finished parts to technical drawings
- European and UAE stock with international supply
- Technical engineering support for grade selection and component specification
Summary
Polyimide is the highest-performance material in the engineering plastics range and is specified where thermal, tribological and electrical requirements exceed conventional high-performance thermoplastics such as PEEK and PEI.
Depending on the application, the five grades provide optimised performance in electrical insulation, self-lubrication, dimensional stability, dry-running operation or electrostatic control, making PI the reference material for the most demanding aerospace, semiconductor, electronics and precision engineering applications.
Frequently Asked Questions
What is Polyimide (PI)?
Polyimide is a super engineering plastic with the widest thermal range in the portfolio, from -269 to +400 degrees C, combined with high wear resistance and excellent electrical insulation for the most demanding aerospace, semiconductor and precision applications.
What temperature can Polyimide withstand?
PI performs from -269 degrees C up to about +400 degrees C, with continuous service around 300 degrees C, above PEEK at approximately 250 degrees C and PEI at approximately 170 degrees C.
When should I choose Polyimide instead of PEEK or PEI?
Choose PI when continuous temperatures exceed the PEEK limit of about 250 degrees C, for dry-running or vacuum high-temperature tribology, or for low-outgassing dimensional stability in semiconductor and aerospace parts.
What components are made from Polyimide?
Typical parts include bearing bushings, thrust washers, wear rings, insulating rings, semiconductor fixtures, test sockets and precision machined aerospace components.
In which forms is Polyimide available?
Polyimide is available as sheets in 360 x 320 mm format, round bars from 2 to 85 mm diameter, cut-to-size and CNC-machined finished parts, across five grades: N, G15, G40, MoS and ESD.
Request a Quote
Plastix Factory supplies Polyimide sheets, round bars, cut-to-size stock and CNC-machined finished parts from production facilities in Austria, Germany, South Korea and the United Arab Emirates.
Contact our technical team or visit the B2B portal at plastixfactory.com/start to check live availability, calculate pricing and place your order.