Round Rod in PAI C GF30 152.4 mm green

PAI C GF30 in round rod format is the raw material for turned engineering parts that have to handle high operating temperatures, high mechanical load and electrical insulation at the same time. The polyamide-imide is compression molded and filled with 30 percent glass fiber, which lifts stiffness markedly and lowers thermal expansion compared with unfilled PAI. The rod is dimensionally stable and forgiving to machine relative to its high performance level. The natural dark tone and matte surface are typical and not a surface defect.

The material is intended for structural components that have to hold shape and stiffness at temperatures where other engineering plastics soften or creep. Common applications are insulated holders in transformers and electric motors, cams and structural parts in pumps and compressors, bushings for medium loads, thrust washers in light applications, valve bodies and structural insulators in semiconductor equipment. PAI is also well proven in soldering fixtures and oven parts where the heat is constant. In high voltage systems too, where the component has to carry load and block current at the same time, PAI GF30 is an economical and proven choice.

Heat resistance sits well above most thermoplastics. Continuous operation is possible far above the PEEK range. The glass fiber lifts dimensional stability rather than heat resistance itself, but it makes the component hold shape and tolerances also when the surroundings get hot or the temperature cycles between low and high values. The low thermal expansion works well with steel and aluminum in assembled designs, which is valuable when the PAI part sits pressed into a metal structure that follows the ambient temperature.

Chemical resistance is broad and stable. PAI handles most organic solvents, oils, fuels, hydraulic fluids and coolants. The material should not be used in concentrated alkalis or strongly oxidizing acids, and hot alkaline water over a longer period can cause hydrolytic breakdown. Moisture absorption is low and does not affect the dimensions to any noticeable degree. This is a concrete advantage over nylons, where moisture both changes dimensions and pulls the mechanical values down. That stability makes the PAI round rod a credible choice for precision parts that cannot be left to chance.

Tribologically, GF30 suits stationary structural components, not sliding bearings. The glass fiber is abrasive against mating surfaces and adds to wear in running contact. If the component is a plain bearing, you pick the CF30 version with carbon fiber and built in lubricating effect, or a PAI grade with PTFE and graphite for even lower friction. If the component is instead a load carrying, insulating or dimension sensitive part, GF30 is often the better and cheaper choice. It pays to separate the two roles already at the design stage, so the material choice drives the component design and not the other way around.

Machining is done with sharp carbide inserts or PCD. The glass fiber wears on the tools and it pays to count on more frequent tool changes than for unfilled PA or POM. Moderate feed, moderate depth of cut in finishing, compressed air or cutting oil for cooling. Avoid water. The component can be post cured to lift the mechanical values further, which is a standard process for demanding applications. For deeper drilling, run a peck cycle and good chip clearance, so you avoid the heat buildup that can leave burn marks. Do not mix PAI up with ordinary PA on the stock shelf, since the appearance is different and the material value differs by several orders of magnitude per kilo.

When choosing a diameter, it is practical to start slightly thicker than the finished dimension, partly for machining allowance, partly to avoid working with material that sits marginally against the drawing. Large diameters are expensive per kilo and sometimes hard to get hold of at short notice, so plan ahead if the project runs long series. It also pays to keep finish machined spare parts in stock for critical components, so downtime at replacement stays short.

In paired designs where PAI GF30 sits against steel or aluminum, it is worth working through the thermal expansions at the drawing stage, since fits that work at 20 degrees can go slack at 200 degrees if the material choices are not thought through. The low expansion of PAI helps, but it is not an automatic guarantee. Do you need to discuss tribology against dimensional stability in your case? Get in touch.