Cutting Tool Engineering
January 2011 / Volume 63 / Issue 1

Pumping up productivity

By CTE Staff

Global demand for oil and gas drives continuing advances in the technologies employed to extract those resources from the ground. A key productivity-boosting technique is hydraulic fracturing, in which fluid is forced under pressure down a well to fracture rock strata or expand existing fractures. The fluid contains sand-like material called proppants to hold the expanded fractures open, increasing flow from the well.

Premium Frac Pumps LLC, Fort Worth, Texas, manufactures pumps used in hydraulic fracturing. The pumps are large and powerful. According to David Capps, manufacturing vice president, the 2,500- to 3,000-hp pumps weigh as much as 19,000 lbs.

Premium Frac Pumps also makes replacement parts. Regular replacement of some components is necessary because the pumps operate at about 15,000 psi, and the high-speed flow of the abrasive proppant mixture rapidly wears pump parts, such as valves and seats. The valves and seats, typically made from 8620 steel castings and forgings, weigh about 5½ to 9 lbs. each.

The shop works 24/7, but demand for the replacement parts began to strain its ability to produce them, Capps noted. The parts were machined on two CNC lathes, one a 4-axis machine and the other a 2-axis unit. Operators manually loaded, unloaded and transferred the parts between the machines.

Seeking a way to keep up with growing demand, Capps consulted St. Louis-based Hartwig Inc., a distributor of machine tools and automation equipment.

Courtesy of Gosiger Automation

Engineered by Gosiger Automation and Hartwig, this cell consists of two Okuma CNC lathes and a Fanuc robot. It increased productivity by more than 40 percent at Premium Frac Pumps.

Dodge Saner, a Hartwig sales representative, said the first step in helping a company like Premium Frac Pumps increase productivity is “sitting down with the customer and figuring out what their needs are. If those needs involve automation, like they did in this case, we will tie in with Gosiger Automation and go back and forth until we find a good solution.”

Gosiger Inc., Dayton, Ohio, is an Okuma distributor and the machine tool builder’s factory authorized automation systems integrator in North America. Mark Eddy, president of Gosiger Automation, said, “We’ve been doing automation for 25 years and there is more to it than just putting a robot in the cell. It involves truly understanding what the customer is doing, his goals and what the possibilities are.”

Together, application personnel from Hartwig and Gosiger engineered a manufacturing cell consisting of a 4-axis Okuma LU-400 lathe, a 2-axis Okuma LB-3000EX lathe and a Fanuc R-200 iB/165 robot. Initial operations are performed in the LU-400 and secondary operations take place in the LB-3000, and the robot loads/unloads parts and transfers them between the lathes. “The automation takes the part out of one machine, flips it and puts it in the other machine,” Capps said.

After heat treatment, the parts are returned to the cell for hard turning of the valve seats.

Greg Feix, Gosiger regional sales manager, pointed out that Okuma machines are good candidates for automation systems because they have “have standard robot interfaces, with the open architecture of the Okuma control being able to integrate via Ethernet versus hardwired discrete I/O.”

Implementation of the cell increased productivity, in terms of parts per shift, more than 40 percent, according to Capps. In addition, direct labor savings led to a 6-month payback.

Although the cell is the shop’s first foray into automation, more is planned. “We are like anybody else in the business,” Capps said, “and we look at our operations all the time and try to get more productive so we can be more competitive.”

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