Technical > Design Guide > Solving problems with Xylan coatings

Xylan stops tapers jamming
CCL Systems makes equipment to pre-stress the steel strands that reinforce concrete structures. One end of the strand is anchored; the other is grasped by a three-part tapered collet and collar held in the jaws of an extremely heavy-duty jack. Loads up to 300 KN (67,000 lbf) are applied until the concrete is set, forcing the tapered parts together.

Freeing the collet once the tension was removed — without permanently damaging the collet — was difficult. CCL Systems discovered that coating the wedges with Xylan 1052 eliminated the jamming completely and ensured reusability.

Xylan unsticks sticky valves
No one pays attention to ball and plug valves — until they stick, which can cause process fluids to be lost, product damaged, energy wasted, even danger to personnel.

Sticking valves are as common as the method generally used to "fix" them: a blow from a hammer, which usually damages the valve in the attempt to unstick it.

A better solution is to prevent the problem from occurring in the first place — with a thin coating of Xylan (25 microns/0.001 in.). Xylan has been used on plug and ball valves for more than twenty years, to provide insurance that the valve will work when it must.

Xylan prevents hot spots
Automotive fan drives are viscous friction drives in which the vehicle's engine engages the fan indirectly via a thin film of silicone fluid. When the engine reaches a speed approximating 30 mph/50 kmph, the air resistance on the fan overpowers the driving torque of the engine, idling the fan and using less energy.

Early in the development of the fan drive, engineers discovered that the drive rotor, in operation, would make contact with the drive housing, causing a momentary hot spot. The heat was sufficient to convert the silicone fluid into a gel, losing the energy-saving effect of the fan drive.

The solution was to coat the rotor and housing with a 25 micron/0.001 in. coating of Xylan 1014 to stop metal-to-metal contact, keep the mechanism running smoothly and eliminate the gelling of the fluid.

Xylan lengthens life of sleeve bearing
A unique powder metal sleeve bearing (developed by Beemer Precision, Inc., of Fort Washington, PA) uses Xylan 1052 to extend its service life in high-load, low-speed applications with rotating and oscillating motions.

The tough nonstick coating virtually eliminates the need for "break-in" because of its low coefficient of friction, which is ideal for startup.

After startup, the coating continues to function, helping lengthen the life of the bearing.

Xylan reduces wear on air-cylinder pistons
In more and more applications, oil/air mixtures either are proving unsafe or they are interfering with process cleanliness.

In environments where lubricated air is not allowed by OSHA regulations or other considerations, air-cylinder pistons should be coated.

The easiest, most effective way to eliminate the oil/air problem and provide proper lubrication for moving parts is to coat air-cylinder pistons with 25 microns/0.001 in. of Xylan 8110, which also extends the lives of the pistons.

Xylan gives 150 million cycles at elevated temperatures
Lubricating a rotor for an automotive air conditioner presented a difficult problem.

The rotor was formed with powder metal, which meant baking to remove impregnants prior to cleaning and coating. Another problem: The unit operated in R-12 refrigerant, which is detrimental to most coating resins.

A coating of Xylan sealed the vane slots in the rotor and reduced friction on the sliding vanes. Qualifying tests showed that the coating withstood 150 million cycles at 8,000 rpm, at temperatures up to 185°C/365°F.

Xylan quiets blower
How much noise can a coating dampen? That depends on the application, but the results obtained in diesel engines are indicative.

By coating only the rotors of a supercharger, a drop in noise emissions of 2.5 dBa was measured and the efficiency of the blower was significantly improved.

Another benefit: In case of a bearing malfunction, the Xylan coating would act as an emergency lubricant to keep the blower from self-destructing until it could be shut off.

Xylan shows stability under fire
Experiments conducted to reduce losses caused by friction in diesel and spark-ignition engines confirmed the problem of friction and demonstrated that this environment was difficult for any lubricant to endure. Matrix coatings, however, had proved their worth in other hot-engine applications.

Xylan 1010 was applied to pistons which were then operated for a quarter of a million miles. The coating showed some signs of scorching — indicating that the pistons ran in excess of 260°C/500°F — but it was still operational, and the pistons showed little wear.

Xylan coating prevents leaks past thread
Pressure vessels, valves, pipe unions, storage tanks, reactors, pipelines and other fluid containment equipment are often fitted with threaded plugs for inspection, pressure relief, filling or tapping.

Coatings on pipe plugs not only improve their performance and reliability but also make them easier to use. A thin film of Xylan eliminates the PTFE tape normally wrapped around the threads to seal them.

In addition, the corrosion protection and low-friction properties of the coating greatly reduce breakout torques, enabling users to remove the plugs at a later date without destroying them.

In most instances, the pipe plugs may be re-used without difficulty.

Xylan coatings are also available in many colors, enabling users to color-code particular plug sizes and alloys.

Xylan proves a winner on the track
Reducing weight and minimizing wear are two major objectives of car designers around the world — especially in car racing. But there's a problem: The lighter the material, the greater the tendency to wear.

Cosworth Engineering, internationally renowned designers of high-performance engines, has solved many design problems with Xylan coatings on engine components:

• Aluminum cylinder liners save weight, but they suffer from scuffing. A collar of Xylan sprayed around the base of the cylinder liner eliminates the problem, even in the engine's hostile environment of heat, oil and friction.
  
• Cosworth replaced steel throttle plates with aluminum, which is lighter, but running between aluminum guides soon caused scuffing. So Cosworth coated the throttle plate and the guides with Xylan, solving the scuffing problem and providing permanent dry lubrication, even in the presence of gasoline vapor.
  
• Magnesium castings are lighter, but contact with harder materials (such as the sintered iron rotor in Cosworth's oil scavenger pump) caused wear, rendering the castings unserviceable. A coating of Xylan 1010 solved the problem. Even after extensive racing trials, no appreciable wear was evident.
  Having proved itself on the race track, Xylan is now enabling production car designers to cut weight and wear as they improve performance — all at a lower cost.