Certainly, moving a punishing mainstay job to an older, looser machine can be risky. But, with proper tooling, it can also raise opportunities to improve efficiency and profitability.

Just ask Peter Dinh, president of Cyber Manufacturing LLC, a busy 60-man job shop in Houston that caters to oil-and-gas industry customers. Cyber Manufacturing moved a very challenging, roughing job from a tight new Mazak to a very loose Kingsbury milling machine dating to 1980, and fiddled with the tooling. Results: a five-to-one saving in machining time, and a six-fold improvement in edge life, leading to a $100,000 yearly savings in machine time and MRO costs.  

The tooling switch was from an Ingersoll IS0-Plus face mill to the same company’s Hi-QuadXXX indexable mill, an unlikely choice because it is nominally a high-feed mill known for fast feeds and shallow passes. But, here it handles depths of cut in the 0.300-in. range. “Our 24/6 operating schedule doesn’t leave much time for error -- or experimentation either,” said Dinh, “so we rely on Ingersoll for quick, practical solutions.”

Quick? For Cyber Manufacturing, the solution was put in place literally overnight. 

The job in question involves rough-milling large process valve gates out of 4140 steel forgings with heavy oxide crusts. It runs continuously at a yearly volume of 500-750 pieces. The roughly rectangular parts measure 29x14x14 in. and need about three-quarters of an inch removed per side, or about 609 cubic inches. The finished parts become very precise sliding gates for big valves used in petroleum distribution systems. Still, the incoming forgings typically have a 0.125-0.175 inch abrasive oxide crust. Coatings on some of them measure more than 0.250 in.

In mid-2014, to free its new 50-HP Mazak for more high-precision work, Cyber bought a 30- year-old Kingsbury with a 25HP, specifically to continue the valve gate job, and tooled it with the same ISO-Plus used on the Mazak. The job ran well enough on the Mazak despite the cutter’s 0.040-in. depth limitation, which required multiple passes even to get through the oxide crust down to bare metal. But, on the looser Kingsbury, cutting edges didn’t last a single pass.

New facemill for vintage machine — Ingersoll field rep Mike Salewsky sized up the problem right away. “Those oxides eat carbide cutting edges for lunch. We have to get through the oxide with the initial pass, regardless of its depth, without overloading the spindle.”

Accordingly he recommended a 3-inch Hi-QuadXXX mill, a high-feed mill with 13-mm inserts able to take off up to 0.250 in. per pass. “The part geometry called for a larger cutter able to go deeper, but the old Kingsbury’s weary bones and horsepower limitation suggested starting small,” said Salewsky.

Assisted by Tam Nyghen of local distributor United Tool and Supply, Mike got the tool to Cyber overnight and came in the next day to set it up and go operational. After a couple of trial passes on the actual part, they arrived at 756 rpm, 75 IPM, 0.200-in. DOC as the optimal parameters. At those settings, the removal rate more than doubled, versus the earlier ISO-Plus. Cutting edges lasted through an entire part, including both sides and 4-6 complete passes.

Even at these settings, the 25 HP spindle showed no signs of overload. Spindle loads stayed well under 60%. And, despite the machine’s loose frame, the operation ran very quietly with no hint of hammering or chatter. “The process was stable, so it seemed worthwhile to go with a larger cutter able to cut even deeper and complete the part faster,” said Salewsky. “Moreover, the oxide skins on some of the forgings run 0.300 in. or more.”