Merrill Tool leans out machines, setups, floor-space and cycle times with fewer, more-capable, boring mills, VTC's and large-part HMC, increasing capacity and opening new markets.
Weak economies hit the manufacturing industry hard, especially in Michigan, but machine shops with the flexibility to accommodate change, diversify their customer bases and run lean, efficient operations are well-positioned to survive when times get tough.
Merrill Tool, a 40-year-old grinding, milling and turning shop headquartered in Merrill, MI, followed a strategy of diversification and lean operations even before the economy began to decline. The shop boasts of flexibility to handle parts under an ounce to more than 50 tons, from under an inch to more than 40 ft. As part of the 400-employee Merrill Technologies Group, the company is sister to Merrill Fabricators, Merrill Engineering & Integration, and Merrill Aviation. Merrill Tool President Bob Yackel has steered a course to diversify his customer base so that no segment of industry constitutes more than 20 percent of the company's sales, focusing on aerospace/defense, machinery-build, automotive, heavy equipment, and oil field as key markets, while rapidly expanding Merrill's work in emerging wind/solar energy.
As a two-shift contract shop with a high proportion of large-part work, Merrill constantly fine tunes its machining strategies and capabilities to make margins on large-part lots as small as one. Tuning up its capacity for an increase in oil-field work, Merrill purchased a MAG RT 1600 boring mill off the floor at IMTS 2006. This increase continued with a second similar boring mill, two vertical turning centers with 2 m tables and, most recently, a horizontal machining center with twin 1250 mm pallets – all acquired from MAG between late '06 and early '09 at a total investment of approximately $7 million.
The first rotary-table horizontal boring mill immediately replaced three retrofitted boring mills, and in doing so increased part processing capacity and reduced machining time by as much as 34 percent. "We purchased our first MAG boring mill to handle new work involving some very large valve parts," said Bob Yackel, President of Merrill Tool. "The capacity of the rotary table, W-axis travel and overall technology are the main reasons we bought the MAG machine. We also liked that it was made in the U.S. and immediately available, because we had an immediate need."
The RT 1600 has a fully programmable 1600 x 2500 mm (63.0" x 98.4") contouring rotary table capable of handling parts up to 25,000 kg (55,100 lb), which has helped reduce cycle times by providing the ability to machine four sides of the workpiece without re-fixturing. There are four options for the W-axis saddle travel – 1500 mm (59.0 in), 2000 mm (78.7 in), 2500 mm (98.4 in) and 3500 mm 137.8 in) – and the single-piece cast bed, with a wide 1310 mm (51.6 in) way spread, adds to the machine's rigidity and accuracy. "We've used the RT 1600 to machine parts up to 42,000 pounds in one setup," said Yackel. "It holds bore locations to ±0.0005 inch, and we can program offline for even better chip-to-chip times." Merrill also uses spindle probes for setup and post-process measurement. Merrill added a second RT 1600 in December of 2008 to provide increased machining capacity for a new wind energy customer, a growing part of Merrill's industry mix. Manufacture of wind energy parts is now approximately 10 percent of the shop's business, where it was zero percent just five years ago. "We'd like to see wind energy grow to be about 20 percent of our overall business which is our maximum target for any industry we serve," said Yackel. "Just like in the stock market, we consider diversification a key strategy to long-term health of the company."
The two RT 1600 boring mills have consistently cut cycle times, reduced setups, and made it easier to achieve specified part accuracies. They have 155 mm (6 in), four-speed spindles with up to 56 kW (75 hp) of power and 7695 Nm (5676 ft lb) of torque. As an example of reduced cycle times and setups, Yackel cites an aluminum fabrication that had previously run on one of the shop's retrofitted boring mills. The new mills cut cycle time 34 percent, from 22 hours to 14.5 hours and eliminated a setup. For another customer ordering fabricating machine columns one at a time, Merrill used the boring mills to cut cycle time 16 percent, eliminate a setup and easily hit the required squareness of 0.0004 in, which had been a problem with the previous machine.
The performance and increased throughput realized with the RT 1600 led Merrill to once again turn to MAG to meet a need for powerful, multi-tasking, vertical turning center capacity for customers in the wind and oil industries, adding a VTC 2000 and VTC 1600 in 2008 and 2009, respectively. Merrill purchased the machines with optional live spindle and live right angle heads to permit multi-functional processing with milling, drilling, tapping and other operations on three surfaces of the part, all in the same fixturing. A full contouring C-axis enables drilling or milling of features anywhere on the workpiece with contouring/positioning by the 360,000 position table. The live spindle and live right angle head deliver 40 hp each. "Originally, we weren't sure we would need a spindle with that much horsepower," said Yackel. "Now I wouldn't buy another machine without it."
In May 2009, as work in wind energy continued to increase, Merrill added a MAG HMC 1250 horizontal machining center with a 110 mm live spindle that was immediately put to work on large turbine component parts. The HMC 1250 Series is engineered for high-precision, high-productivity, large-part machining with 1250 x 1600 mm pallets and a maximum 3000 mm (118 in) work zone swing range, 2050 mm (81 in) work height capacity and 7000 kg (15,400 lb) work load. A standard 360,000 position contouring table enables precision 4-axis machining of a variety of part geometries. The HMC 1250 features six spindle options including two sizes of live spindles (110 mm or 130 mm), high speed (24,000 rpm), high-torque (2600 Nm/1918 ft lb) and a new 6000 rpm tilt spindle.
The relationship between MAG and Merrill has expanded beyond "machine tool provider and job shop customer," with Merrill now machining parts for MAG machines – a case of having the right equipment to meet customer needs. "As a job shop you never know who your next customer is going to be or what you are going to be asked to manufacture," said Yackel. "Having the latest technology, multi-tasking capabilities and the machine capacity to handle large parts opened a lot of doors for us into new industries so we can protect our business with strong market diversification."
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