The Right Tools Conquer Forging-Scale Nightmare

May 22, 2008
Kennametal milling cutters bust through forging scale to reduce tooling costs by half and triple productivity.
With Kennametal milling cutters, Premium Frac Pumps can achieve 80 to 100 cu-in. per minute metal-removal rates.

Premium Frac Pumps in Fort Worth, Texas, is a thriving 33- employee, $10-million enterprise, producing heavy-duty equipment for the demanding oil- and natural gas-drilling industry.

The company machines 12,000-lb, 60-in. by 30-in. by 30-in. blocks of forged steel into 5,800-lb fluid cylinders that have many complex holes used to attach other components, and ultimately ships completed pump assemblies to the field.

Kevin Riley, the company’s president, started the operation with three CNC milling machines and a $50 million purchase order for the pumps.

Energy companies use the pumps to inject a high-pressure mixture of sand and water into the earth to break up well blockages. Riley, who expects his company to reach between $30 million and $40 million in sales next year, credits Kennametal Inc. ( for much of Premium Frac Pumps’s success.

Kevin Riley (left) and Dominic Freeze stand in front of a finished frac pump assembly that takes 54 hr to machine with Kennametal cutters, as compared with the previous 180 hr.

“Within eight months of opening, we started shipping product, but the product was taking a long time to produce,” said Riley. “There wasn’t a whole lot getting done because it was taking us about 180 hours to machine each part.”

“Scale on a forging is a nasty nightmare. There’ll be hard spots and soft spots and the hard spots are extremely tough to get through. In the forging process, it’s tough to get a forging to cool evenly, so you end up with this scale on the outside. A lot of our forgings come in with a half inch of scale,” Dominic Freeze, lead programmer for Premium Frac Pumps, said.

Premium Frac Pumps went through a lot of competitive tools and inserts on its Toshiba and Koraki horizontal milling machines, and the situation was costing the company about $20,000 per month in inserts.

When Kennametal applications engineer Mark Davis learned of the problem, he suggested using a 6-in. Kennametal BMD600R8607S150L250 face mill to get through the scale on the outside of the forgings.

Davis brought in Kennametal milling specialist Dave Stewart to help optimize the scale busting and other milling processes on the fluid cylinders.

Machining the scale off of one side of the forging required three indexes on a competing face mill. The Kennametal team removed the scale and sized the block on the same corner, saving significant indexing time.

They further optimized the sizing and shaping process with another new Kennametal milling product, a 6-in. indexable face mill — the Dodeka cutter KSHR600HN5345M8

Both the BMD600R8607S150L250 cutter and the Dodeka cutter use grade KC935M inserts, a multi-layer CVD coated grade designed for dry machining at high feedrates.

The BMD series cutters offer a depth of cut capability to 0.500 in. using a 1-in.-diameter by 0.375-in.- thick positive insert for heavy milling with a minimum of four indexes per insert. The Dodeka cutter has 12 cutting edges per insert with 0.178-in. depth of cut capability.

“It was so much of an improvement over what we were doing, we had no choice but to switch. The Kennametal cutters are extremely free cutting. I’m able to increase depths of cut, cover more surface footage, and have greater material-removal rates. We’re taking 80-cu-in. to 100-cu-in. cuts, which is insane. Now, thanks to the Kennametal tools, the one-time 180-hr job is done in 54 hr, at about onefourth of the cost,” Freeze said.

Not only has speed improved, but so has productivity.

Before using the Kennametal tools, Premium Frac Pumps was able to finish one or two fluid cylinders per week. Today, it completes one every day.

“Before, we’d empty our 30-yard chip hopper once every couple of weeks. Now we have to do it every day, sometimes more than once a day,” Freeze said.

Premium Frac Pumps has had such a positive experience with the Kennametal face mills that the company now is in the process of converting completely to Kennametal tools.

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