Saint-Gobain Seals' Specialized Bonded Rulon Bearings Continue To Excel In Aerospace And Defense Applications

Saint-Gobain Seals continues to successfully provide specialized and beneficial bonded Rulon filled PTFE bearings to manufacturers in the aerospace and defense industries, utilized in such applications as jet engine thrust reverser and missile launch systems. Most linear bearings in these industries need to be integrated into the mechanical structure of the overall system, which are then typically bonded to a metal substrate. In applications that require linear bearings, their Rulon product is an ideal material due to reducing weight, eliminating lubrication, and minimizing maintenance while providing high performance and a long lifetime.

The process of bonding Rulon or any filled PTFE material to a metal surface can be a difficult task as PTFE does not naturally lend itself to bonding because it has one of the lowest surface energies and is hydrophobic. Saint-Gobain Seals has been bonding their Rulon material to metal for decades, with thousands of hours of successful results in the aerospace and defense industries. One of the reasons for their success is due to the material characteristics of certain Rulon grades, which have been designed specifically for bearing use. These characteristics include a low coefficient of friction, wide temperature range, low wear, and high load capacity.

The first step to bonding the Rulon product is to chemically etch the material. Next, the proper adhesive must be chosen for compatibility with both the Rulon material and the metallic substrate as it must be applied properly and be able to maintain the bond in the intended environment and application. The processes of etching filled PTFE and then bonding it to a metal surface can be very delicate, sensitive to time and environment, and dependent on precise manufacturing techniques. Without the proper experience, the materials can be damaged during the manufacturing process or quickly degrade while in use.

A popular application of Rulon bonded bearings is in thrust reverser systems on jet aircraft. A thrust reverser system helps slow down an aircraft just after touchdown, resulting in shorter landing distances, reduced wear on brakes and improved safety. One common system consists of doors built into the engine nacelle. When closed, the doors are integrated into the shape of the exhaust section of the engine, allowing for forward thrust. When deployed, the doors open to block the rearward flow of the exhaust, redirecting the exhaust forward and thus causing deceleration of the aircraft. Rulon bonded bearings enable consistent, smooth deployment of the doors with low stick-slip under severe high and low temperatures.

Rulon bonded bearings have also been used in missile launch systems. Many systems hold a missile inside a canister, which also functions as a launch tube. When the missile is fired, it escapes the canister while sliding against the canister's internal structure at a high speed and in an extremely hot and dry environment. To ensure proper missile operation and extend the lifetime of the reusable launch system, a high-performance linear bearing surface for the missile to slide against is essential. The Rulon product is an ideal material due to its low coefficient of friction, resistance to wear, and its ability to withstand brief periods of extreme heat.

Saint-Gobain Seals is the only source of genuine Rulon polymer material. Each standard Rulon material and hundreds of other custom Rulon blends have been developed to meet a set of specific application requirements while also remaining versatile. Some popular materials for bonded bearings in aerospace and defense include their Rulon AR and Rulon W2 grades. This product line not only assists aerospace manufacturers but also has been used in other industries such as transportation: Rulon J sliding elements for the bogie of new 7000 Series trains in Washington DC, Rulon J glide rings for bicycle rear shock absorbers, and Rulon 123 piston cup seals for gasoline metering pumps.