Salvaging cylinders

END USER: Whayne Supply Co., (800) 494-2963, www.whayne.com.
CHALLENGE: Resurface scratched and rusted cylinder barrels in-house.
SOLUTION: A tube hone machine.
SOLUTION PROVIDER: Sunnen Products Co., (800) 325-3670, www.sunnen.com.

Rebuilding hydraulic components on construction and earth-moving machinery makes good economic sense. The rebuilding trend since 2008 has been strong enough that Caterpillar dealer Whayne Supply Co., Louisville, Ky., added a machine shop in 2009 to its existing hydraulics shop in Corbin, Ky., which rebuilds hydraulic pumps and cylinders. Whayne performs Cat-certified rebuilds of complete machines at its two Power Remanufacturing Center rebuild facilities in Louisville and Corbin. The company has 16 locations and about 1,300 employees overall.

The machine shop includes two vertical mills, two lathes, a drill press, a rotary surface grinder, welding equipment and saws. The shop has five cylinder service bays: one for suspension cylinders, one for lift cylinders on small loaders and three for high-force cylinders. “We can replace the barrel, rod, rod eyes, head and seal areas, hydraulic lines and connections, or custom fabricate new cylinders to spec,” said Michael Carter, the shop’s service coordinator.

Caterpillar dealer Whayne Supply hones cylinder barrels up to 21 ' long.

Sunnen’s HTA series tube hone allows Whayne Supply to resurface scratched and rusted cylinder barrels.

The machine shop also has an HTA series tube hone machine from Sunnen Products Co., St. Louis, which allows Whayne to resurface scratched and rusted cylinder barrels, saving customers 80 percent or more compared to the cost of a new barrel. Sunnen brought the machine in as part of a beta test of the new all-electric HTA tube hone in 2009. Whayne later purchased the machine, which has a 12 ' (3.7m) part capacity.

There are four hydraulic cylinders on the average Cat machine, so the shop stays busy, processing about 1,000 cylinders a year. “During the summer, we may have a hundred or more cylinders outside our shop waiting to be rebuilt because our indoor storage is full,” Carter said.

The shop’s old hone consisted of a drill motor on a sliding carriage and lacked sufficient power, capacity and rigidity, according to Carter. “It could produce a surface finish, but not remove metal.”

The Sunnen tube hone handles parts weighing up to 8,000 lbs. (3,629 kg) with IDs from 2.5 " to 21 " (63.5mm to 533mm) and removes up to 0.030 " (0.76mm) of stock.

“The new tube hone has proven extremely reliable and we’ve used it to hone barrels from 2.5 " to 17 " (63.5mm to 432mm) in diameter and 6 " (152mm) to more than 21 ' (6.4m) in length,” Carter said. “We simply created a table with an adjustable-height V-block to support parts that overhang the machine. We have used up to a 21 ' driveshaft length on the machine, and we can hone from both ends of the part if need be. Our cycle time for most barrels is about 30 minutes, which includes setup, honing and washing the part.”

Whayne uses both roughing and finishing abrasives, removing scratches and rust and imparting a crosshatch pattern on the barrel bore. Producing a controlled crosshatch pattern allows the honed surface to retain oil or grease, ensuring proper lubrication and ring seal of pistons in cylinders.

“We can increase the barrel bore diameter up to 0.010 " (0.254mm) in a relatively short time, removing rust and all but the worst scratches, and remain within Cat machine specifications,” Carter said. “Our old hone simply could not do this. We scrapped a lot of cylinders or sent them out to other shops prior to acquiring this machine. Now we can salvage a cylinder with honing. In the current economy, customers appreciate the savings.”

Bringing this previously outsourced machining work in-house has helped the company add revenue, while also improving control of delivery schedules. “Simple economics dictate that customers are going to be rebuilding machines until the economy and the coal industry in our region strengthen significantly,” said Mike Harbin, manager of the remanufacturing center. “We have customers who are tearing down machines in the field and completely rebuilding them. The machine shop and the tube hone have helped us stay on top of this trend. We have added five people in our shop alone to handle the increased volume.” CTE