November 2007 Edition

CUTTING TOOLS

Scale Nearly Unbalances Profits

At times, getting through nearly an inch of scale on forgings was killing production until a shop put the right cutting tools on the job

Scale was literally murder for cutting tools at Premium Frac Pumps, Fort Worth, TX. The company machines 12,000 lb, 60"×30"×30" blocks of forged steel into 5,800 lb fluid cylinders with many complex holes for attaching other components, and ultimately ships completed pump assemblies to the field. Frac pumps are used to inject a high-pressure mixture of sand and water into the earth to break up oil well blockages.

"Within eight months of opening, we started shipping product," Kevin Riley, president of Premium Frac Pumps – PFP – said. The company began operation with three CNC milling machines and a $50 million purchase order for the frac pumps from energy companies.

Scales of Injustice

But, the machining of workpieces took a long time because of the scale on them, according to Dominic Freeze, lead programmer of PFP.

"There wasn't a lot getting done because it took about 180 hours to machine one part," Freeze said.

"Scale on a forging is a nightmare. There are hard and soft spots. The hard spots are tough. When forgings cool unevenly scale develops on the outside. A lot of our forgings come in with a half inch of scale on them."

Machining the scale off of one side of the forging required three indexes and took a week to finish one or two pieces. Insert costs were about $20,000 per month.

During a visit by Mark Davis, an application engineer from Kennametal, Inc., Latrobe, PA, he suggested using a 6" Kennametal cutter to get through the scale on the outside of the forgings.

Davis brought in Dave Stewart, a Kennametal milling specialist, to help optimize cutting through the scale and other milling processes. The milling cutter and improvements suggested by the Kennametal team took hours off of this process.

PFP saw tooling costs cut in half and productivity triple in its 33-employee, $10 million facility.

"We expect productivity will be three times what it was and the cost about half."

The company had gone through a lot of tools and inserts from other companies on its Toshiba and Koraki horizontal milling machines until it found the right cutters for its ­dilemma.

Obvious Improvement

"The new cutters were so much of an improvement that the switch to them was obvious," Freeze said. "They're free cutting. I'm able to increase depths of cut, cover more surface footage, and have larger cubic inches per minute of material removal. We're taking 80 to 100 in 3 cuts."

Now, jobs that took 180 hours are done in 54, at about one-fourth of the cost.

Proof of the speed improvement can be found in PFP's chip hopper.

"Using the other cutters we'd empty our 30-yard hopper every couple of weeks," Freeze said. "Now we empty it every day, sometimes more than once a day."

PFP has had such a positive experience with the Kennametal face mills that the company now is in the process of converting all of its tools to Kennametal products.

"We expect productivity will be three times what it was and the cost about half," Freeze said.

Growing from its original three machines, PFP now has 12 CNC machines and is expanding into a 40,000 ft² building across the street from its original facility, a 27,000 ft² building which will be dedicated to assembly operations, with the new building committed to machining.

Riley, PFP's president, said he expects his company to reach up to $40 million in sales. Kennametal

Visit www.rsleads.com/711mn-201 for more information

What do you think?
Will the information in this article increase efficiency or save time, money, or effort? Let us know by e-mail from our website at www.ModernApplicationsNews.com or e-mail the editor at pnofel@nelsonpub.com.