PPA, polyphthalamide
PPA is the tougher cousin of nylon. Same family, but with an aromatic backbone that makes it stiffer, drier and far more heat resistant. A step up when PA6 loses its shape in the heat and PEEK feels needlessly expensive.
What it is
PPA stands for polyphthalamide and is a partly aromatic nylon. The difference from ordinary PA6 sits in the chain: the aromatic rings make the material stiffer, more heat resistant and less inclined to soak up moisture. Moisture is exactly the weak point of nylon, since the dimensions shift as the material takes up water, and that is where the big advantage of PPA lies. You keep what is good about nylon, the wear resistance and the machinability, but you get a part that holds its shape better in heat and moisture.
Common applications
PPA sits in parts that have to carry load in heat: pump housings, valve parts, bearing bushings and components close to an engine or a process. It is used where PA6 no longer reaches, but where PEEK would be overkill.
Limitations
PPA is more expensive than ordinary nylon and comes in a narrower selection of formats and dimensions. The material still takes up some moisture, less than PA6 but not none, so for really dimension critical parts in a wet environment POM or a fluoroplastic is a safer choice. If you need to go higher in temperature, PEEK or PPS is the next step.
Grades and variants
We stock PPA in natural. Other versions and dimensions can be ordered in on request.
- PPA natural, the standard version. Sheets and round rods in natural.
Machining
PPA is turned, milled, drilled and tapped like the other nylons, but the material is harder and wears the cutting edge more. Sharp carbide tools and a calm feed rate are what applies here. If the part has to hold tight dimensions, it is worth conditioning the material before final machining, just as with PA6.
Formats we can supply
We carry PPA as sheets and round rods in natural. If you want a piece cut to size, enter the dimensions in VisualCutter and you will see the price right away.