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END USER: Neenah Foundry Co., (920) 725-7000, www.nfco.com. CHALLENGE: Increase productivity and worker safety when measuring castings on a coordinate measuring machine. SOLUTION: A system that enables a CMM operator to load and unload castings in fixtures with minimal lifting, bending or twisting and easily move parts into the CMM's measurement zone on plates supported by air. SOLUTION PROVIDER: Mod Tech Industries Inc., (715) 524-4510, www.modtechindustries.com
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Neenah (Wis.) Foundry Co. manufactures gray and ductile iron castings for the municipal market, such as manhole covers, grates and frames, as well as industrial components for the heavy truck, off-highway, HVAC and agricultural sectors. To ensure dimensional requirements and specifications are met during the initial sample process and monitor tooling wear via periodic measurements of castings throughout the life of the component, the company performs measurement on a coordinate measuring machine. Nee- nah’s CMM has a measuring envelope of approximately 3 '×3 '×4 '.
The castings weigh from 5 to 250 lbs. Positioning castings on the CMM table for measurement can be a challenge. Although Neenah uses a hoist for the heavier parts, the parts have to be positioned near the center of the CMM. In addition, workers find it time-consuming to change each part because of the setup time required, according to Dale Allen, the company’s metrology supervisor. For example, it may take 5 minutes or longer to set up a part on the CMM in preparation for the measurement program and just as long to disassemble the setup. This time is unproductive because the CMM is idle.
Courtesy of Mod Tech Industries
The AAM system from Mod Tech enables a CMM operator to move parts to be measured on a plate that’s supported by air.
Mod Tech Industries Inc., Shawano Wisconsin, is a production machine shop that machines castings for Neenah Foundry and other foundries throughout the region. To meet capacity restraints and increase measuring productivity on a CMM, Mod Tech developed what it calls the Air Assist Movement (AAM) system. With the system, air is expelled through channels and ports underneath an aluminum plate, which lifts a plate and subsequent casting to be measured so a CMM operator can easily move the plate into the measurement zone and position the plate locators against locator stops. “It is similar to an air hockey table, but instead of air from the table lifting the puck, air from the plate lifts it off a CMM’s granite table,” Allen said.
When Neenah Foundry witnessed the system at Mod Tech, it purchased an AAM system from Mod Tech and had it installed. Today, Neenah assembles a fixture and casting on one of the system’s two plates from the side or front of the CMM while the other plate, which supports a second casting, is being measured. Once the measurement cycle is completed, which can take 10 minutes or more, the CMM operator activates the air valve and moves the plate with the measured part out of the measurement zone and moves the second plate with the newly secured part into measurement position. The operator then begins the measurement cycle on the second part.
At this time, the operator removes the previously measured part and stages another one on the empty plate. The only time the CMM is idle is during the shuttle process. “You have virtually seconds for change time instead of minutes,” Allen said, noting that parts “glide into place. It doesn’t matter how heavy they are. We’ve done a 1,000-lb. part and you can move it with one hand once you get it started.”
According to Mod Tech, a 20 "×20 " plate can lift and move more than 1 ton. Standard plates are available in 12 ", 16 ", 20 ", 24 " and 30 " square sizes.
Allen added that the AAM system is also safer because all set up is performed at the edge of the CMM table rather than in the middle. “It helps save your back,” he said. “You don’t have any pulling or pushing to get things into place.”
The plates contain both sleeved and threaded holes in a grid pattern on the top surface for locating fixtures. Once a fixture for a specific part is completed, it is placed in the same plate location every time to ensure part position repeatability. Allen noted that he creates a part-specific setup sheet that indicates the hole locations used according to the X- and Y-axis positions identified on the plate, such as A2, C7 and E9. “I simply record which holes the fixture is positioned to and how tall it is,” he said.
Although a CMM has its own air supply and a line can be split off from that for the plates to plug into, Neenah Foundry uses a separate line from its main air system, roughly 90 psi.
Since Neenah purchased the AAM system about 1 year ago, it has provided a full return on investment, according to Allen. “We have easily doubled the output of the CMM,” he said. “We are looking to purchase another CMM and will put an AAM system on that one too.”
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