This section was edited by Associate Editor Alan S. Brown.
SINTERING GOES AIRBORNE
Direct manufacturing, the use of sintering and other additive processes to manufacture production parts, has established itself as a method for making products such as dental implants or molds. Now Electro Optical Systems GmbH would like to add aerospace parts to the list.
EOS is teaming with the Boeing Co., specialty chemicals maker Evonik Industries AG, rapid tooling manufacturer MCP HEK Tooling GmbH, and University Paderborn to form the Direct Manufacturing Research Center. The five founding members and the German state of North Rhine-Westphalia expect total funding for the center to reach 11 million euros over the next five years.
 The ability to produce complex, conformable cooling channels in hot parts is a key reason aerospace companies are interested in direct manufacturing.
The center itself will focus on laser sintering and laser melting systems for metals and polyamides. “Direct manufacturing offers the potential of significantly reducing parts production costs, as well as enhancing the ability to fabricate more complex and more functional component parts,” said Jeff DeGrange, manager of direct digital manufacturing at Boeing Phantom Works, who will head the consortium.
Within weeks, EOS also announced that it will sell a plastics laser-sintering machine to Northwest UAV Propulsion Systems, which plans to use it to make cylinder head shrouds and temperature controllers and other parts for unmanned aerial vehicles. Northwest’s president, Chris Harris, said that the system enables it to achieve consistently tight tolerances without using such secondary finishing operations as sanding.
According to Jim Fendrick, vice president of EOS of North America Inc., the company has worked with Boeing to identify roughly 130 aircraft parts that can be laser-sintered before and he narrowed down the field to fewer than 10 parts to start with. Most of those will use nylon resin, although EOS is also working on plastics with greater heat resistance.
EOS said it is working with another manufacturer, which it did not name, to sinter metal parts for the hot sections of jet engines. The company has developed grades of chromium-cobalt and Inconel superalloy for its sintering process. “It’s very easy to do conformable cooling channels, which keep parts cool in hot engines, in direct manufactured parts,” Fendrick said. “These channels are hard to cast.” He added that often the channels in cast parts are not as efficient as those in sintered parts.
COMPOSITES FOR HYBRIDS
by Jeffrey Winters
With automakers across the globe scrambling to react to record-high oil prices, it would be natural to assume that car designers would use every tool available to increase fuel efficiency. But designers have yet to fully embrace composite materials, according to John Busel, director of the composites growth initiative for the American Composites Manufacturers Association.
“The younger designers haven’t worked a lot with composites,” Busel said. “They’ve tended to stick with steel because that’s what they know.”
To help sell Detroit on the advantages of composite materials, ACMA has conducted a benchmark study on potential weight savings from replacing steel parts with composites on a typical hybrid vehicle. Busel said that designers were keen to find a way to make cars lighter without making them smaller, since many potential car buyers were concerned about safety risks from smaller vehicles. Lighter cars would be able to get higher fuel economy.
The study began by stripping an existing hybrid model of various steel parts, such as the bumpers, fenders, trunk compartment, and hood. For each of these parts, researchers working for the association assessed what a composite-based substitute would look like and how it would be made. They found that not only would composite parts be up to 50 percent lighter, but also would require much less investment in tooling to create them. That’s because composite molds are less expensive than steel stamping equipment, and single composite pieces can replace several steel parts that have been welded together.
For example, the study found that the module holding the battery pack, electronic controller, and other critical systems, which is normally fabricated from numerous metal stampings, could be made from two molded pieces. In addition, composite materials are insulators, which is a significant safety consideration.
Busel said he hopes the benchmarking study will get automakers to begin considering composite components as a normal part of the hybrid vehicle concept. “On the high end of the market, sports cars and the like, there’s an extensive use of composites,” Busel said. “But on a Crown Victoria, which is a huge car, they choose to use very little composites. It’s a cultural thing.”
SENSORS TAKE INVENTORY
Inventory management has not changed much since the cuneiform incisions of Mesopotamia detailed the state of the royal stockrooms. Sure, there are carousel shelves, computerized pick lists, and robotic pickers. Still, someone eventually has to walk back to the stock room and take a count.
Now, Loadstar Sensors Inc., a Silicon Valley startup firm in Mountain View, Calif., has developed a plug-and-play solution to inventory management. The concept behind its iLoad sensor is so obvious, it is breathtaking: Measure inventory with a weight sensor on each bin of parts and send the data to a computer.
“Our secret sauce,” CEO Div Harish said, “is that we combine a weight sensor element, digital processing, and communications into one unit that gives you high-level digital output.” That output comes through an industry-standard USB port, the most common connection used to plug devices into a PC. “It’s like a digital camera; you just plug it into your computer and it gives you a number,” Harish said.
Harish’s microelectromechanical sensors use capacitance to measure changes in weight. They output a linear signal of 0.5 volt at zero load and 4.5 volts at full load, a dynamic range that provides accurate detail and also makes it easy to convert the signal into data that can travel over a USB connection.
 New weight sensors can show when bins are running out of inventory, and plug directly into a network or PC using a standard USB connection.
The key, said Harish, is keeping the system cost-effective. He said that units start at $99 a sensor. Any mechanical engineer can install the units without specialized assistance, and up to 50 sensors can be linked into a network concentrator. That is big enough for a large set of inventory bins. Users can collect inventory data in Microsoft Excel spreadsheets or Loadstar’s proprietary inventory management software.
“There is a huge demand for this, especially among contract manufacturers,” Harish said. “They’ve got hundreds of different fasteners and parts they need to track. Right now, most of them are using manual processes where half the effort is scanning each bin to see what they need to replenish. This solution can eliminate much of that work.”
The company says it has trials under way with several large users, including large automotive suppliers. It plans to begin sampling demonstration units in the third quarter and start selling in the fourth quarter this year.
RESIN IMPROVES FIT AND FINISH
Before it became SABIC Innovative Plastics, GE Plastics introduced Noryl GTX resins for fenders and other vertical car body parts in 1985. At the time, the ther-moplastic had a coefficient of thermal expansion much higher than automakers wanted. But there were advantages to using it. So thanks to some engineering redesign, General Motors Corp.’s Saturn division and 22 other automakers have used the resin on millions of cars.
Now, SABIC returns with a new grade, GTX 977, which has 25 percent lower thermal expansion properties and can be painted on industry-standard electrostatic coating lines.
 Designed for the vertical parts, GTX resin from SABIC Innovative Plastic expands less in the heat but remains flexible in the cold.
Thermal expansion is a key element of fit and finish, since it determines how close automakers can mount auto panels. Parts made of low thermal expansion materials like steel (12 x 10-6 millimeter per millimeter per degree Celsius) enable manufacturers to mount fenders and door panels very close together. This makes a car look solid and well put together. Plastics have higher thermal expansion rates and require easily noticed gaps between panels that detract from the quality look of a car.
The first GTX resin had an expansion rate of nearly twice the linear 50 CTE that manufacturers wanted. SABIC used some fancy engineering to make the resin acceptable.
“We learned how to attach fenders to a car so they only expand forward,” said SABIC’s global market director, Derek Buckmaster. “Take a front fender, for example. We attach segments of the part solidly at the parts of the fender closest to the rearview mirror. Forward of that, toward the headlamp, we have elements that can slide back and forward. We also have sliding elements under the rearview mirror that slide vertically.” The design enabled SABIC to hide gaps under bumper and wheel well fascia.
Plastics have undeniable benefits that make all the effort worthwhile. They reduce vehicle weight, do not rust, and bounce back from bumps that would dent steel and other less flexible materials. While GTX costs more than steel sheet, it runs on relatively inexpensive injection molding machines rather than multimillion-dollar steel stamping presses. Companies with relatively short product runs (50,000 to 125,000 cars per year) often prefer to pay higher material prices than invest in heavy equipment.
GTX 977 makes plastics still more attractive. First, it reduces thermal expansion rates by 25 percent compared with earlier GTX resins, to 70 x 10-6 millimeter per millimeter per degree Celsius, so engineers can design closer gaps in their panels.
SABIC does this by adding a filler to the resin. Most fillers are tiny needle-shaped particles that make plastic stiffer but also more brittle, especially in cold weather. Buckmaster said GTX’s new technology uses rounder reinforcements that improve stiffness and dimensional stability while retaining the plastic’s flexibility.
The particles also impart enough conductivity to GTX to coat on an industry-standard electrostatic paint line. “That’s a real savings because manufacturers can put the panels on at the start of the line rather than breaking into their painting operation later to attach them,” Buckmaster said. He said five or six companies are already testing the new grade.
SMALL LATHES
by Harry Hutchinson
A machinery company in Oxnard, Calif., has found that smaller shops increasingly do shorter product runs that include multiple operations. It wants to help them out, so it is offering two small-footprint lathes priced at under $30,000. The company, Haas Automation Inc., says the machines can boost productivity in small and midsize shops where floor space is at a premium.
One of the models, GT-10, has a footprint of 82 x 85 inches, a maximum cutting length of 8 inches, and a maximum cutting diameter of 10 inches. The other one, GT-20, is 96 x 73 inches on the floor, with a cutting length up to 12 inches and a diameter to 11 inches. The GT-10 has a 7.5-hp motor and a price of $25,995. The GT-20 has a 20-hp motor and costs $28,995.
Haas sells the lathes without tooling. Options include a pneumatic chucking system for the GT-10 and a hydraulic chucking system for the GT-20. An optional eight-station tool turret is also available for both machines.
According to Scott Rathburn, marketing product manager at Haas Automation, the GT-10 and GT-20 are smaller, less expensive alternatives to the company’s SL-10 and SL-20 turning centers for shops that don’t need a tailstock or longer turning length capacity. The Haas SL-20, for example, has a maximum cutting length of 20 inches, but the machine is much larger than the GT-20, and has a base price of $54,995.
 Small footprint: Two new lathes from Haas Automation are designed to fit shops where floor space is at a premium.
Haas suggests small lathes for secondary operations in short production runs with multiple orders. Rathburn described one possible scenario. Turned parts often require secondary operations to finish the back side of the part (the portion held in the chuck). If the work is done on a single machine, the operator must manually flip the part and then perform the secondary operation. Each piece is handled twice on the same machine.
For a reasonably small investment, a shop can have a second machine available for the finishing work. The primary turning operations, which typically are more complex and have longer cycle times, can be done on one machine, using a bar feeder and automatic parts catcher to increase throughput and run unattended. The secondary operation can then be done quickly by the same operator on a secondary lathe like the GT-20, and thereby increase productivity.
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