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First CNC Machine, Arrow VMC hits Bull’s Eye for Small Mold ShopMonroe Custom Molds received much more than they expected when they upgraded from manual production to a Cincinnati Arrow 750 VMC. The upgrade provided them with half the setups, 75% less machining time, and helped them target future growth.
Company Profile: Monroe Custom Molds
Location: Monroe, NC
Established: 1990
Products: Multi-axis machining of molds, dies and other contoured/freeform structures
Market Area: Charlotte, NC —Spartansburg, SC industrial area
Number of Employees: 6
Facility Size: 1200 ft&Mac178; (112 m&Mac178;). A new 7800 ft&Mac178; (725 m&Mac178;) structure to be built in 1998
President and Owner: David McAteer
Cincinnati Sales Agent: GBI Cincinnati
MONROE, NC— It took seven long years of bootstrapping effort for David McAteer to get his tool and die business on solid ground. Now he's aiming for breakout growth for Monroe Custom Molds (MCM) by bringing together a bow and "Arrow". The bow, a promising new design of a nationally ranked archer, requires CNC contour machining of a key component. And the Arrow, a Vertical CNC Machining Center from Cincinnati, made 3D processing of the freeform part economically viable.The Monroe shop's first CNC machine, the Arrow VMC-750 proved an ideal choice for the "point position" in upgrading the business from manual to CNC production, says McAteer. Installed in October, 1996, the Arrow made a strong impact by raising their level of technology, competitiveness and productivity. For starters, he notes, the new VMC enabled the shop to:
* Process die sets and injection molds faster by reducing setups and benching.
* Bring out-sourced work in house.
* Respond aggressively to growth opportunities, such as the bow project and 3D tool, die and mold work created by the rapid industrial build-up in the greater Charlotte area.
The Arrow not only helps MCM to grow and explore new ways of doing things, its open-architecture CNC even allowed the machine's capabilities to grow and evolve, notes McAteer. To that point, he just completed upgrade of the Acramatic 2100 (A2100) CNC to a high-speed die/mold processing package added by Cincinnati as a machine option.
Arrow Makes a Bow from Solid 6061-T6
When area resident and nationally-ranked archer Dave Tetrick first approached him with his bow idea, McAteer had to turn him down. "With our manual equipment, I couldn't get the part cost down enough for his target market price," he says. "The machinist time and setups would have been extreme. Everything is 2-axis and 3-axis work because of the contours."
The Arrow VMC made the project a winner. The core element of the bow, the riser, is contour-machined from aluminum plate. "We start out with 13 pounds of 6061-T6 solid bar and finish it down to two pounds," says McAteer. "The Arrow allows us to run these parts in 25% of the time and with half the number of setups it would take on manual equipment."
McAteer had already begun window-shopping for the right machine to up-grade the manual shop to CNC, even before Tetrick approached him. Intrigued by the bow project's potential, McAteer upshifted his search for a new VMC. He saw that the move to CNC would enable the shop to perform more work in-house and take advantage of opportunities created by strong industrial growth in the area. "We were sending a lot of work out to other shops to do CNC milling on our mold bases and die sets."
Most for the Dollar
As a small business, however, McAteer knew a wrong decision on a CNC machine could be devastating. He carefully investigated nearly every machine on the market over a two-year period before deciding on Cincinnati's Arrow VMC. "We looked at everything in this machine size —low end models to top of the price range," he says. "Cincinnati wasn't the cheapest, nor the most expensive, but it offered the most for the dollar."
He cites the following areas where the Arrow stood out:
* Cincinnati was one of the few machine makers that included and guaranteed a metal removal rate in its literature. Most only specify torque and horsepower, but with nothing to judge how well the machine applies that power. In fact, notes McAteer, his machine operator says he's able to take 25-30% heavier cuts on the Arrow than on other VMCs he has run.
* The 40-taper Arrow uses the same spindle component technology as Cincinnati's higher end, more powerful 50-taper Lancer VMCs, giving extra strength and rigidity.
* The Arrow provides four to five times more tool retention force than any other machine in its price and size range. "We feel like that's another big factor in the accuracy and rigidity of the machine," says McAteer.
Routine Machining of Pre-Hardened Steels
The Arrow's strength, rigidity, and accuracy pay off for MCM in the machining of demanding mold and die steels. Progressive stamping dies are typically machined from A2, D2 and 4140 pre-hardened steels, he notes, while injection molds and vacuum-form tooling utilize S7, H13 and A6.
"We're able to cut all the holes and features into a progressive die set in one setup on the Arrow," says McAteer. "We draw everything on the CAD system and finish the die shoes on the Arrow, including the dowel pin holes. We're putting those right on the money. Before, we would have to transfer all the locations to the blocks and line up everything piece by piece. The Arrow saves us a lot of assembly and mounting time on these progressive dies."
Superb Mold Machine
Similarly, the Arrow has proven superb at 3D contour machining of molds, especially in precise match-up of mating parts and parting lines. "The Arrow's saved lots of bench work and really made everything easier for us on these parts," says McAteer.
The Arrow holds tolerances of ±0.0002" (5 microns) in machining pockets into the mold bases that hold locks for aligning mating mold halves together.
The shop also uses the Arrow's precision to do engraving work on the molds, anything from cavity or part number to product name and customer logo.
On big surfacing projects, MCM typically roughs out the material on the day shift with an operator. The CNC machine does the finishing at night, unattended. "We've let it run up to 12 hours unattended through the night doing finishing passes and 3D contouring with ball-nose end mills," says McAteer. "It's just been great for our productivity."
MCM extends the Arrow's productivity by also using its 3D contouring proficiency to machine graphite EDM electrodes. "A lot of electrode work is 3-axis," notes McAteer. "We've equipped the Arrow with a vacuum system so we can pull out the graphite dust."
Sold on A2100 Control
The Arrow's Acramatic 2100 CNC has been a big factor in the VMC's versatility and high productivity, says McAteer. "There's so much depth and flexibility to the control," he says of its touch screen navigation and Windows NT information presentation. "It gives you so many ways you can set it up and use it."
He also appreciates having touch-screen capability supplemented by a standard keyboard at the machine. "We found the alpha-numeric keyboards on other machines were a little awkward and slow," he says. "This way, the programmer has a keyboard that fits and feels the same as the one at his computer. It just makes entering and editing information easier and more comfortable."
He praises the Arrow for providing a third operator interface —a hand-held mobile pendant that can go with the operator. "This is extremely helpful in stepping through a mold program," says McAteer. "That was a big gripe with one of my operators when he ran a CNC mill at another shop. While trying to touch off on a part or come down slow and see how it would affect the cut area, he had to lean into the machine while trying to stretch his arm back to run the control. Holding the pendant in your hands lets you keep a close eye on things and respond quickly to what's happening."
CNC Grows with Open Architecture Options
McAteer has taken advantage of the A2100's open architecture to make two option upgrades to the CNC.
First, MCM purchased an Ethernet card so it can download programs straight from the shop computer. "With some large surfacing programs, we didn't have enough memory in the control to accept the whole program," explains McAteer. "Now we can run straight off the shop computer; no more transferring everything to floppies and disk swapping."
Second, MCM installed a high-speed mold and die processing package, now available as a CNC option. This upgrades the control to a Pentium processor for a host of performance advantages:
* 50% faster drive axis motor response.
* Triple the block processing speed —from 4.5 ms to 1.5 ms.
* Increased intelligent lookahead from 20 to 120 blocks, allowing the control to better "read and react" to up-coming axis changes.
* Double the RAM memory of the real time processor from 4 mb to 8 mb, allowing larger programs to be run straight off the machine hard drive.
"This die/mold package lets us go after more 3D contouring work," says McAteer, "allowing us to process molds faster, yet with higher precision."
Keys for Survival
The "growable" A2100 fits one of McAteer's keys for survival in the job shop metalworking business. "You have to keep up with technology and keep your equipment updated," he says. "The Arrow gives us a machine structure that's built to last, while keeping up with advances in control capabilities."
Another key is being willing to wear more than one hat. "In a small shop environment like ours, everyone has to do more than one job, whatever it takes to get the work out the door." The Arrow fills that role on the equipment side of the equation with its versatility, he stresses.
Finally, there has to be a willingness to work a lot of hours, especially when getting started in business. Again, the Arrow provides a match on the machine side with its ability to run unattended, he says.
The Arrow has done everything MCM expected, says McAteer, but its biggest contribution was unexpected. "The great surprise for us with the Arrow and the A2100 control is how they enable us to look at and handle jobs in new ways and do things differently."
Arrow Bags Bow McAteer sees the bow business, just getting started, as having huge potential. So far, Monroe Custom Molds has machined risers and other parts for several hundred bows. These have been selectively marketed to competitive archers with the intent that their word-of-mouth reports will build top-down demand.
Compound bows use a system of pulleys to amplify the archer's draw force. The riser provides a rigid main frame that the flexible, composite "limbs" of the bow can bend against to provide the energy to drive the arrow.
"Everything else attaches to the riser —the handle, sights and all the other components," says McAteer. "It's the foundation. Traditionally, risers were cast, but now bow makers are shifting to machined risers for greater strength and stability. I've seen cast risers break under the stress."
The geometry of the riser is free-form, requiring extensive 2- and 3-axis contouring moves. MCM machines all faces of the riser in three setups. It even used the Arrow to create the fixtures to hold the parts for machining. MCM also makes cams and wheels for the compound bow's pulley system.
"We believe the sport will really take to a bow designed by a competitive archer," stresses McAteer. "This could develop into a full line of target bows, hunting bows, and models for women and children. Archery is quite a family sport." In fact, he reports that his 15-year-old son, Jeremy, has taken it up as a result of the family's involvement in the bow project.