Sheet in PAI C CF30 254x254 mm black

PAI C CF30 is a compression molded polyamide-imide reinforced with 30 percent carbon fiber. It is one of the most heat resistant thermoplastic materials that can be machined in an ordinary workshop, and the carbon fiber content lifts both the stiffness and the dimensional stability considerably compared with unfilled PAI. The sheet is supplied in a natural dark brown shade. The surface has the characteristic matte finish that comes from the sintering and post-curing process.

The heat resistance sits in the top layer of engineering plastics. The material keeps its mechanical integrity in continuous operation well above the temperatures where PEEK starts to lose stiffness, and it takes short exposure to temperatures approaching the working range of the fluoroplastics. The carbon fiber gives a low and directionally stable coefficient of thermal expansion, which is decisive when components have to fit against steel or aluminum across a wide temperature span. The thermal conductivity also rises compared with the unfilled grade, which is a concrete advantage in applications where frictional heat needs to be led away from the bearing surface instead of building up locally and accelerating the wear.

Tribologically, PAI C CF30 is developed specifically for plain bearings, piston rings, sealing rings and thrust washers that run dry or with marginal lubrication. The carbon fiber works as an internal lubricant and locks in a low coefficient of friction even at high PV values. The wear is very low and the material does not create abrasive wear on the mating steel surfaces to the same extent as glass fiber filled alternatives do. This is the difference between a bushing that lives for twenty years and one that has to be replaced at every annual service.

The chemical resistance is broad. PAI handles most organic solvents, hydraulic fluids, oils and fuels even at elevated temperature. The material should not be exposed to concentrated acids or strong alkalis for longer periods, since the ester bonds in the polymer structure can then be broken down by hydrolysis. The moisture uptake is low and does not affect the dimensional stability the way it does in polyamides. That makes the material credible in precision components where the tolerances have to hold through the whole life cycle, not only on delivery.

The sheet is used in applications where no other thermoplastic is enough. Common examples are valve components in compressors and pumps, guide pins and bushings in lightweight machinery, washers in rotating equipment, insulated electrical parts in high temperature environments and machined fixtures for the vacuum and semiconductor industry. It is also common as high strength insulators in electric motors and as bearing material in furnace equipment. In aerospace and defense, PAI is an established choice for components that have to combine low weight with extreme temperature resistance.

Machining calls for sharp, wear resistant tools. Carbide or PCD does the job, but the carbon fiber is abrasive and the tool life gets shorter than when machining unfilled engineering plastics. Use sharp inserts, moderate feed and good chip clearance. Drilling deep holes calls for peck drilling and good cooling, preferably with compressed air or mineral oil. Water is to be avoided, partly because of the moisture uptake, partly because thermal shock combined with the cutting residues can give micro cracks in the surface. The material can be post-cured to lift the mechanical figures further, which some designs require in order to use PAI to the full.

When choosing the thickness, keep in mind that larger cross sections get considerably more expensive per kilo than thinner ones. Many drawings can be solved with a thinner sheet plus finishing work. If you need higher thermal conductivity and a stronger bearing characteristic you pick the CF30 variant. If you instead need the best possible dimensional stability in low voltage components, where the tribology matters less, the GF30 variant suits better and is cheaper to machine, since the glass fiber is somewhat less aggressive against the cutting edge. For the very best sliding properties there are also PAI grades with PTFE and graphite added, but then you lose some of the pure structural strength.

Do you need help choosing the right PAI grade for your component? Get in touch and we will go through operating temperature, mating surface and load together. This product, PAI C CF30 254x254 mm black, has the format 254x254 mm, which makes it easy to place in an existing design.