Round Rod in PEEK MG 3000 mm blue

PEEK MG is one of the most used PEEK grades in bearing engineering. The polymer is PEEK, and the additive consists of a balanced blend of carbon, graphite and PTFE that works as a built in lubricant. The round rod is therefore meant for sliding pairs where you do not want to, cannot or cannot be bothered to lubricate continuously. In practice it is used in applications where grease lubrication is not permitted for reasons of hygiene or is simply impractical to maintain, and in applications where the operating temperature sits too high for conventional grease or oil lubrication.

Mechanical performance sits close to pure PEEK. Tensile strength is around 116 MPa on the base resin, ball indentation hardness 253 N/mm² and impact toughness good but not in the class of unreinforced PEEK. Density is 1.31 g/cm³, water absorption 0.03 percent. In terms of temperature the material handles 260 degrees long term and 300 degrees briefly without losing shape or mechanical properties in a way that affects function. Thermal conductivity of 0.27 W/(m·K) is typical of the PEEK family, and dimensional stability at temperature is good, which is valuable when the tolerance chain in the machine is tight.

Typical applications are turned sliding bushings in pumps, valves and compressors, guide sleeves in hot machinery, gears in low modules where dry running is required, and wear rings and distribution rings. The material suits well when the mating body is steel, brass or hardened steel and continuous lubrication is awkward to arrange. The PV value is high, and the coefficient of friction sits several tenths lower than pure PEEK in its operating environment. For gears under medium load at temperatures around 100 to 200 degrees, PEEK MG is often a good compromise between wear resistance, noise level and tolerances, compared with metal gears that need constant lubrication. The material is also used in seal elements and guide elements in pneumatic and hydraulic components, where the mating body is often hardened steel and wear would otherwise take out shorter lived parts in POM or PA quickly.

Chemically PEEK MG is as resistant as the base polymer. Hydraulic fluids, oils, solvents, alkaline media and weak acids the material takes without trouble. Hot water and steam are handled well, which makes the material useful in food plants and in process engineering. Concentrated sulfuric acid and strong oxidizing acids are borderline cases that call for review. The fire rating is V-0 without flame retardants. Resistance to radiation is good and the material takes repeated steam sterilization without aging, which makes it useful in healthcare and laboratory equipment.

Machinability is good. Use carbide tools with sharp edges, moderate feeds and good cooling when turning. Thin walled, slender parts should be rough turned, stress relieved and then finish turned to final size to avoid dimensional drift after machining. Polishing is possible, and the material keeps a relatively fine surface once turning is finished, which lowers the risk of stick slip against the mating body. Bonding is difficult, mechanical joints work without trouble. Tapping threads in the material also goes well, but pick an M-tap with a generous chip flute and run with good cooling so the thread walls do not melt.

The rod is stocked in standard diameters from roughly 6 mm to 100 mm and in lengths around 1000 mm. It can be cut to blanks. The natural color is dark gray to black, which is typical of the carbon and graphite content of lubricant filled grades.

For sizing plain bearings in PEEK MG there are two numbers that govern: permitted PV value and permitted contact pressure. Both depend on temperature, so if the application works at an operating temperature above 150 degrees you should scale down contact pressure and PV against the room temperature figures. For gears, module, face width and the pinion to gear ratio are the variables that together with the mating body decide whether PEEK MG is enough or whether you need to step up to CF30 reinforced PEEK MG to hold down tooth misalignment under load. When picking the bearing wall, the guideline is to keep the wall thin but not thinner than about 1.5 mm, so it takes the press fit and the thermal expansion without cracking. If the bearing is pressed into a steel housing and the operating temperature sits high, there is a risk that the fit shrinks in service, which has to be counted in from the start.

The blue MG rod at 3000 mm is turned into healthcare parts such as bushings and spacers, with blue color coding all the way through the material.

For a choice between PEEK MG, PEEK MD or pure PEEK in a specific sliding pair application, a short sizing discussion is recommended where we look at mating body, load and temperature profile. Call or email and we will work it out together.