Material guide
PAI, polyamide-imide
PAI, polyamide-imide. One of the most heat resistant and mechanically strongest plastics we carry, made for parts that have to hold together when both heat and load pull at them. This is the top tier of the high temperature plastics.
What it is
PAI, polyamide-imide, sits at the absolute top of the high temperature plastics. The material combines very high mechanical strength with one of the highest continuous service temperatures you will find in a machinable plastic, and it keeps its stiffness and strength even when it is really hot. It is stiff, dimensionally stable and has good abrasion resistance, which makes it a material designers go to when nothing more ordinary is enough. PAI belongs in the premium segment and is one of the more expensive materials in the range, so it is chosen when the requirements are extreme. It is available both as an unfilled grade and in filled versions, more about that under grades.
Properties
Very high mechanical strength, carries load even when it is hot
Among the highest continuous heat resistance of the machinable plastics
High stiffness and good dimensional stability under load
Good abrasion resistance, works in hot plain bearings
Inherently flame resistant with low smoke development
Filled grades are available for even better glide or higher stiffness
Common applications
PAI is used where heat and mechanical load meet and ordinary plastics give up. Typical parts are plain bearings and bushings in hot environments, sealing rings and wear parts in compressors and pumps, plus washers, spacers and insulating components in electrical engineering and electronics that have to take high temperatures. It also turns up in vehicles, aviation and process industry where a part has to handle both heat and wear without losing its dimensions. When the requirements are so high that PEEK is no longer enough, PAI is often the next step.
Limitations
PAI is one of the most expensive materials in the range, so it is chosen only when the requirements genuinely justify it. If your part is fine with what PEEK or PEI can take, you are paying for PAI unnecessarily. The material normally needs a heat curing process after machining to reach full performance, which makes handling more demanding than for a standard plastic, something to allow for in lead time and process. For purely chemical environments there are better choices among the fluoroplastics, and for everyday mechanics without heat requirements POM or PA will do fine.
Grades and variants
PAI is available in a couple of grades that solve different needs. Which grade suits depends on whether the part is primarily to slide, carry load or hold its dimensions when hot.
Base grades
- PAI unfilled grade, the unmodified plastic. First choice where the highest strength and stiffness in heat weigh heaviest.
Additives and reinforcements
- Lubricant additive, for better glide and lower friction in bearings and wear parts.
- Filler, for higher stiffness and dimensional stability.
If you are unsure which grade suits your part, we will help you choose.
Formats we can supply
PAI is available as sheets and round rods. You see formats and dimensions in the range. Would you like a piece cut to size? Enter the dimensions in VisualCutter and you will see the price straight away.