Picking up speed

Wichita, Kan.-based Harlow Aerostructures LLC had a good problem. Customer interest was rising for a two-part assembly that it had produced infrequently in the past, so it needed to find ways of cutting down machining time to meet demand.

The 67-year-old aircraft components manufacturing shop has a wide range of aerospace manufacturing capabilities, producing components that range from large bulkheads, spars, chords, and stringers, to small bushings, bolts, pins, and bearings. The company specializes in developing prototypes through close integration with customers in extremely short lead times.

For the problem-causing assembly, machinists at Harlow had been using older machines to make numerous shallow cuts in the roughed component assembly. The company didn’t need to produce a polished, finished part, but the 150-person shop needed to ramp up speeds.

Harlow production manager Aaron McCulley says, “A time-consuming roughing operation for the two-part assembly, our past methodology was to take small depths of cut and use older tools. The parts had not been run frequently in the past, but larger orders were coming up.”

Harlow was running the parts on one of its three Dah Lih Machinery Co. 3-axis machining centers. Cut from 4130 steel at 500sfm with a 1.5" depth of cut, Harlow employees cut the parts using a dry tool with a 27.5in3/min metal removal rate.

Machining the two parts took more than two hours – an hour and 15 minutes for the first piece and 50 minutes for the second.

After meeting with officials from Iscar Metals at a seminar, McCulley says the company decided to test new cutting tools to see if it could cut cycle times.

“The only tool we looked at was the (Iscar) ECI-H4R 750-1.5/2.25W04CF. The part structure needed to have a smaller diameter cutter to be efficient. The [metal removal rates] were vastly superior,” McCulley says.

Set-up time for the new tool is 30 minutes, and once running, cycle times fell dramatically. Part 1 fell 89% from more than an hour to only eight minutes. With Part 2, cycle times fell 90% to five minutes from nearly an hour. Between the two components, machinists got more than a tenfold decrease in cycle times.

“Iscar brought their end mill in and we were blown away. We went from taking four axial passes to doing it in one pass,” McCulley states. “Just that change cut our time by 75%. We also ran the Iscar cutter twice as fast, which cut out even more time.”

Another benefit has been longer tool life, he adds.

“The cost of the cutter might be quite a bit more up front, but the savings as we ran the parts was remarkable,” McCulley says. “We have been using this cutter for quite a while now on these parts and it is still impressive to stand there and watch the chips literally fly off the part.”

Harlow has long used a technology-driven strategy to stay ahead of the competition, using automated, lights-out machining and developing new electronic management tools, such as website portals, to offer supply chain management capabilities to suppliers and order-management tools for customers.

McCulley says using the best cutting tools it can find fits right into that strategy.

“The machine shop industry is so competitive today that we are always looking for an advantage over other shops both here and in other countries,” McCulley says. “Because of this end mill and many other cutters we use from Iscar, we feel like have a tremendous advantage over our competition.”

Harlow Aerostructures LLC
www.harlowair.com

Iscar Metals Inc.
www.iscarmetals.com
IMTS 2014 booth #W-1800