It happens more often than a contractor wants.
Eventually, a hydraulic cylinder seal riding against a chrome surface day after day will fail, or the rod could be the victim of corrosion or an external impact. A leak develops and the problem must be fixed quickly.
Repairing the surface of this rod can often lead to loss in machine productivity and expensive downtime. Some contractors may have to ship the part to have it chromed, adding travel delays to the mix, too.
But Advanced Chrome Technologies (ACT), a division of Ring Power Corp., hopes to change this all-too-prevalent interruption in machine productivity.
Since February, the company has offered a thermal spray process using high velocity oxy-fuel to resurface worn and damaged cylinder rods. The process got its start in the aerospace industry, but, "it's new to the construction equipment industry," said Mark Newman, hydraulic business manager.
The $1.3-million investment had been in the works for approximately one year before it launched. Ring Power is one of only three construction equipment dealers in the United States and six in the world to have this system.
Newman said the Advanced Chrome Technology Team of seven employees in Riverview, Fla., (near Tampa) can usually resurface a hydraulic cylinder rod in one shift with the ACT process — just four to six hours. In comparison, the average lead-time for chrome plating is three to five days. With two shifts working a day, Newman said the ACT crew can conceivably refurbish eight to 10 pieces a day.
How ACT Works
The process is handled in five steps. In the case of a hydraulic cylinder, it starts with the disassembly of the cylinder. The rod, head and piston are removed and the piston and head are taken off. A detailed inspection follows to see if the rod is straight and if there is any surface damage. If the cylinder is bent, it is straightened.
In the next step, the rod is taken to a grinder where the chrome is stripped off using an aluminum oxide belt and ground down to ten thousandths under finish diameter. This takes the cylinder down to bare metal and usually fixes any surface damage.
The third step is to grit blast the surface. This specialized machine uses a coarse material to clean and provide a surface texture. The machine is computer-controlled to provide the proper preparation. At this stage, workers measure the roughness of the surface to determine when it is ready for the next step. They are looking for an RA of 250 to 300. Since the next step is to spray it, they must keep the part free of contaminates so they use paper to wrap it to move it to the spraying machine.
The thermal spray process sends a combination of hot combustion gases and a fine chromium carbide powder at 5,000 F through a nozzle at a velocity of between 4,500 and 5,000 ft./sec. This process provides the strength to the surface by embedding the material in the cylinder rod. Careful control and monitoring of this part of the process is critical. The temperature of the piece being coated must remain below 300 F. If it goes above this threshold, the spraying is stopped until the piece cools down.
The final step is to grind the surface down to the final dimensions with a diamond belt. Because of the difficulty in grinding down the ACT material, workers make every effort stay very close to the final specifications during the spray process. The difference in belt costs, $15 to grind off the chrome versus $400 to grind down the ACT material, shows the difference in abrasion resistance, according to Newman.
The technique isn't limited to hydraulic cylinders. It also can be completed on rods, linkage pins and any rotating shaft. Newman said his shop can handle any cylindrical part up to 12 ft. long and 12 in. in diameter.
A hydraulic cylinder sometimes needs to go through the chrome plating process three or four times during the life of a machine. "But once you rebuild it with the ACT process, we may never see it again," Newman said.
In a head-to-head test, Caterpillar researchers determined a chrome plated cylinder failed at approximately 350,000 cycles, while the ACT coating was still holding at 1 million cycles, when the test ended.
"The ACT process, while being slightly more expensive than chroming, has two real advantages," said Newman. "The first is speed. With the ability to repair a part in one day versus three to five for chroming you get your equipment back up and work quicker. The second is reliability. You get superior resistance to corrosion, oxidation and mechanical wear."
Ring Power's ACT division is working with many of the equipment dealers around Florida and the Southeast, as well as many contractors. In the future, Newman said the ACT division may diversify outside of the construction equipment business and look into providing the service for other industries. CEG Staff
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