PEEK compounds continue progress in wear-resistant applications

The latest polyetheretherketone (PEEK)-based semi-finished product from Saint-Gobain Seals Group (Garden Grove, CA) has been specifically created for tribological applications -- in particular for moving components in applications where friction and wear rate at contact points are significant parameters for consideration. Meldin 5530 is available in the form of compression or injection molded and machined components, as well as basic shapes for the "ultimate in customization and design flexibility."

Wear rates and PV limit are superior for last PEEK grade.Rotors and gears (pictured here in a gerotor; a type of positive displacement pump) are target applications, as are thrust washers and piston rings.The new grade reportedly complements the Seals Group's extensive offering of high-performance materials developed for similar applications for bearings, rotors, gears, thrust washers and piston rings, including those based on performance thermoset polyimide (PI) materials.

Whenever top performance is required from a thermoplastic material, design engineers have a limited number of choices according to Saint-Gobain Seals Group. PEEK is one of the few thermoplastic materials able to operate above 230°C (445°F), and Saint-Gobain Performance Plastics has adopted this base resin as its backbone for the Meldin 5000 product family. Generally the market offers only four standard PEEK grades. However, Saint-Gobain Performance Plastics has developed multiple proprietary formulations that can address application challenges

Tribology plays an important role in manufacturing, adds the Seals Group. Controlled wear on components limits their replacement, which translates into savings deriving both by fewer number of parts needed during the lifetime of the equipment as well as number of production stops for maintenance operations. Friction is also a key parameter; when high, it increases the power that is needed to operate a piece. The potential savings offered by materials with improved tribological properties are therefore significant.

Material development of the Meldin 5530 grade included rigorous wear and friction testing, conducted internally at well-equipped laboratories at different Saint-Gobain Seals Group site locations. There are many factors that influence the behavior of tribological applications such as pressure and speed, type of motion, environment (dry or lubricated), temperature and mating surface (type of material, finish and hardness). Thorough testing provides a good indication of wear and friction ranges as well as PV (pressure x velocity) limits that characterize the different materials analyzed and therefore, can be used when designing parts out of these materials.

The behavior of the new Meldin 5530 grade is said to be exceptional in terms of both reduced friction and wear and in line with polyimide or polyimide-amide compounds, even under dry conditions, which translates into extended service life and lower risk of failure for the systems in which the parts are installed. Due to these high-performance properties, Meldin 5530 material represents an excellent choice for parts like rotors and gears, but also thrust washers and piston rings when conditions are too demanding for the Seals Group's other well-known and established grades, Meldin 5330, 5350 and 5055.

In other recent developments at Saint-Gobain, a Meldin 5000 PEEK-based offering has been selected for packing kit backup rings for a down hole drilling application in the oil and gas market. The backup ring parts are used in a hydraulic drilling jar that helps free and move the drill pipe components in the event that they become stuck in the formation.  The drilling jar is versatile and operated on land, offshore or ultra-hot boreholes.  For this high-pressure, high-temperature (HPHT) drilling application where temperature can rise up to 500°F and the system pressure in thousands of PSI, the back up ring parts provide excellent durability through superior thermal resistance combined with strong mechanical properties and chemical resistance.