Shop Solutions:Technology Boosts Microelectronics Manufacturing
It was easy for almost anyone to turn a profit in the machining business prior to 2000. That's the belief of Mohamed Shahin, president of Sandy Bay Machine (Rockport, MA). Today, the executive says it's much more difficult. That's why his company has begun investing heavily in advanced technology so that whenever the market turns, the company will be better positioned to compete with the shops still standing.
Sandy Bay is a world-class manufacturer of microelectronic components, typically for antenna, microwave, and aerospace applications. It has more than 30 CNC machines manufacturing precision workpieces for a diverse base of companies like Boeing, Lockheed Martin, Motorola, and Raytheon.
Sandy Bay's manufactured components are mostly complex, electricalbased components, requiring sophisticated, reliable manufacturing techniques. The slightest inaccuracies result in scrapped products, and small lot sizes and quick turnaround runs are often required.
In 2003, Sandy Bay purchased a standalone a51 HMC from Makino (Mason, OH). "Our Makino a51s did exactly what Makino had promised," explains Shahin. "The a51 reduced the cycle time of the part we tested from 25 to 15 min. The surface finish visually improved as well. In another instance, it took us 2 1/2 hr to run four parts on our old machine. On the a51, we reduced the cycle time to 40 min."
Several other legacy machines were not performing to Shahin's strict standards, so he made the switch to the a51. "The Makino machines were the only HMCs that could hold the 0.0002" [0.005 mm] tolerances we needed in our complex parts," says Greg Osmond, Sandy Bay's production manager. "We looked at other machines, but the Makinos were the only ones that could cut complex parts accurately."
Among the products manufactured at Sandy Bay Machine is a satellite antenna that holds circuits to divide microwave signals. The part's 0.00035" (0.009 mm) tolerances require a 3/32" (2.4-mm) tool with a 16" (406-mm) extension, boring two holes in precise locations over 9" (228 mm). The part's surface flatness has to be matched within 0.001" (0.03 mm).
"We don't drill often, and boring allows for increased surface straightness. As a result, the roundness and concentricity are perfect," says Osmond.
Filter housings are another part Sandy Bay regularly manufactures. The part measures 15" (381-mm) wide by 13" (330-mm) long by 1.75" (44-mm) thick, and requires a substantial amount of hog-out work before it reaches the finished size.
Surface finishes must also be considered. Osmond explains: "Most parts are coated with silver, gold, or another material in the end to aid in conductivity and sensitivity for the final application, so this must be taken into account when programming. Some parts require a 0.02" (0.51-mm) radius on the corner, which means lots of cutting with a small end mill. Makino's Super Geometric Intelligence helps eliminate corner chatter, a problem we've had in the past. With the Makinos, we can reduce cycle times because the tool doesn't slow as it enters corners nearly as much as with other machines. And we don't have toolchatter problems anymore," Osmond asserts.
Sandy Bay has made a flexible manufacturing system, the Makino Machining Complex (MMC2), the center of its manufacturing operation. The MMC2 features a pallet-handling system, two worksetting stations with 24 pallets feeding three Makino a51 HMCs.
"The Makino Machining Complex gives us the flexibility to run many jobs at once without major operator intervention," says Osmond. "We can program and set up several jobs and call them up whenever we need them, without having to reprogram and re-setup the machine. This results in more uptime and less setup time on common jobs."
According to Osmond, the Makino Machining Complex has cut setup time by 50%. Shahin has also said that he can actually connect to the system via the Internet from a remote location to check on work progress.
To further optimize production, Sandy Bay makes its own tombstones. "The Makinos can machine accurately everywhere in the work zone, even high in the Y [axis]," says Shahin. "Confidence in the equipment's accuracy no matter where we're machining allows us to fixture many parts per face of each tombstone, often up to 12 or 16 parts per face on a five-sided tombstone. This reduces out-of-cut time and pallet changes, and allows us to produce parts in specific batch sizes completely based on the customer's needs."
The spindle runs 94% of the time on the MMC, which amounts to much more up-time than achieved by the VMCs and standalone machines in the shop. Shahin attributes the remaining 6% of downtime to routine maintenance.
Sandy Bay was worried that part accuracy would suffer without an operator standing in front of each machine, but management quickly found that the MMC produced parts just as accurately as a stand-alone Makino. In fact, the system provides more stability and reliability in the process, reducing the variables for error.
"This technology gives us confidence that we can deliver on the contracts we are bidding on, no matter what the quantity, accuracy, or delivery requirements are, and helps us attract and retain good employees," explains Shahin.
"Skilled workers are hard to find," explains Shahin. "Having a continuously evolving company goes a long way in attracting potential employees. We were able to change from three to two shifts, leaning more on optimized equipment like the MMC to pick up the slack. The third shift was always the hardest to find workers for, and many of those employees were glad to move to the day shift."
The successful implementation of the Makino a51 MMC has encouraged Sandy Bay to continue down the path of automation. While the company currently has a two-levelhigh pallet stocker MMC system, Shahin plans to purchase a new MMC that will be a three-level-high system.
Recently, Sandy Bay joined other leading manufacturers under the TSI Group Inc. (North Hampton, NH). Under this new ownership, the company is expecting continued growth, with a goal of doubling their revenue in two years.
"We are showing the success of our MMC to the other companies in the TSI Group every day, and have become an example of how productive a flexible, automated production system can be," says Shahin. "This investment will allow us to come out of tough times stronger and more competitive, instead of closing up shop like so many others."
For more information on Makino Inc., go to www.makino.com or telephone 513.573.7200.
Engineering an Aero Fixed Stator Case
TK Engineering (Cincinnati) sought a turbomachinery manufacturing company in 2004 to design and produce a fixed stator case as part of the United States Air Force (USAF) Small Business Independent Research support of the Unmanned Aerial Vehicle Propulsion improvement program. Selected was Concepts NREC (CN; White River Junction, VT, and Woburn, MA) for its ability to meet the required quality and cost specifications.
"We had other companies' estimates for doing this project," says Bob Turnbull, chairman of TK Engineering. "Concepts NREC was the most capable company, and it came in with the best price, so we wanted them to work with us. The fact that they did it less expensively was important. We already had the contract. It was a question of using the money we had most effectively, and we feel we did so," Turnbull asserts.
Following five years of development, completed parts were delivered as scheduled. The extended timeframe reflects the design's evolution from an aero design to a mechanical concept design, and then to a manufacturing concept requiring new technology.
"This was a very advanced compressor from the aero standpoint, primarily because of the pressure ratio and high objective efficiency on the axial compressor," says Turnbull. "The pressure ratio had to be 13:1, making it a high-risk design that, in the end, required an advancement in engineering technology."
Blading for the axial and centrifugal compressor was based on TK's aero design requirements. The parameters required an overall pressure ratio of 13 in two stages: an axial pressure ratio of 2.5 and a centrifugal pressure ratio of approximately 5.2.
Turnbull says that achieving the centrifugal pressure ratio is not difficult. "Enough wheel speed will get you that. The real challenge was the axial ratio of 2.5 in a single stage."
CN had to change the inside configuration of the axial rotor to reduce stresses on the part. Jeff Pfeiffer, CN director of business development, explains: "It was a very unique configuration because of its internal shape. We worked with a subcontractor to perform the difficult internal machining work, and assisted them by making some design modifications to make sure the area was accessible."
Manufacturing the axial rotor initially appeared to be achievable only by casting, but material strength requirements didn't allow it to be cast. It had to have forgiving properties. Ultimately, the axial rotor part of the project became an intricate tooling assignment requiring machining inside the bore to form the semi-ball-shaped design to reduce stresses.
The fixed stator part of the project originally didn't appear to be as challenging, because it was considered to be a multiple-piece design that could be welded together. It ended up having to be redesigned as a single or integral piece, and posed a similar machining challenge to the axial rotor, because the original one-piece design couldn't be machined due to limited access to the vane-ring area.
"We developed new tools and methods to manufacture this product," says Bill Pope, CN director of operations.
After design analysis on the parts, CN determined that the casing could be done as two separate axial parts initially so that the stator vanes could be accessed for machining. Circumferential electron beam (EB) welding of the casing was done immediately ahead of the stator vanes to gain access for machining. Then, the two parts were EB welded together, and a final machining process performed to final specifications.
To handle sand ingestion, a US Army requirement, Inconel 718, a superalloy, was chosen. Using Inconel 718, which requires a heavy chip load when machining, made the manufacturing process more challenging, as production required boring on a lathe and new design considerations. Custom tooling was developed and tested to withstand the cutting force and achieve the required dimensions and surface finish.
The center of the vaned ring was removed with a P01404 drill and SMO08436 blade insert from YG-1 Tool Co. (Vernon Hills, IL). Roughing was done with CNMG 642-KC5510 and CPMT 3252-KC5510 inserts from Kennametal Inc. (Latrobe, PA).
The vane ring was semifinished using roughing mills. This part required two operations and was oriented on two 0.125" (3.2-mm) diam fixture holes drilled at two locations with rough mill blades on the flange side. A C40 U five-axis machining center from Hermle Machine Co. (Franklin, WI) was used and equipped with an end mill (RA216.23-1250BAK09P) from Sandvik Coromant Co. (Fair Lawn, NJ) and standard length collet holder.
To prevent distortion of the airfoils, CN applied heat treatment for age-hardening once rough machining was complete. The parts were heated to 1350°F (720—720°C) for 8 hr then furnace cooled to 1150° F (620° C) for 8 hr using BodyCote thermal processing.
The vane rings were finish-machined on the Hermle C40 U machine with a Sandvik Coromant RA216.44-1230 AK06N ball mill with standard holder HSK63A and a 3" (76-mm) end-mill extension.
Inconel 718 was also used for the fixed stator case, which was developed as a design using individual vanes intended to be brazed to the outer case. In typical aero designs, the fixed stator case and related parts are machined as separate pieces, and the blades are usually brazed together in a slide-in ring assembly. TK Engineering preferred making all the parts integral with the outer case.
The blades were positioned radially inward, which presented a new challenge to CN engineers who didn't want the blades to relax or spring after they were machined, affecting the performance of the machine.
"The blades of the impeller look like potato chips with a ring around them," Pope says. "Our CAM department developed new capabilities by intermingling toolpaths created with both our MAX-SI and MAXAB CAM software modules. Doing this, along with choosing the proper cutting tools and toolholders allowed us to completely access the area and accurately machine the vanes. The methods we developed on the fixed stator can now be applied to future projects."
CN's engineering group used its Agile Engineering Design System software to engineer the fixed stator case product and its MAX-PAC software module for machining. The project from receipt of contract to manufacture of the product took five years. It took three weeks to work out the machining process once the engineering was complete, and CN engineers verified that the design was sound through analysis and testing. From beginning to end, it took three to four months for manufacturing, including test cutting and final production.
Through its experience with the TK Engineering project, CN developed advanced technology to produce three parts: an axial rotor, an integral fixed stator case, and a special diffuser for which CN designed the centrifugal compressor. The new concept in design and manufacture of the fixed stator case has potential for commercial and military small engines.
For more information on Concepts NREC, go to: www.concepts nrec.com or telephone 802.296.2321.
Chips Can't Clog Cast-Iron Machining
Coolant management has long been a critical element in machining operations. The increased speeds and higher metal removal rates of today's newer CNC machines create more chips, placing increased demands on the coolant and on associated chip removal and coolant filtration equipment and processes.
Many machining operations have moved to high-pressure coolant systems for faster chip removal and greater precision. This puts increased stress on the fluid, magnifying the adverse effects of chips or other contaminants.
The stress on coolant is compounded when cast iron is machined, as Ansco Machine Co. (Cuyahoga Falls, OH) recently discovered. Ansco is a contract manufacturer that specializes in milling and turning engineered parts from carbon and alloy steel, ductile and grey iron, aluminum, plastics, and exotic alloys for the hydraulics, automation, and general-engineering industries. Typical parts include gear boxes, actuator housings, steel brackets, and aluminum castings with powder coating and engraving. Specialties of the company include machining thrust rings from 1045 ring-rolled forgings in diam from 7 to 63" (178–1600 mm).
Cast-iron machining for the advanced energy industry is performed on five-axis a81 HMCs from Makino (Mason, OH). High-performance CNC lathes and machining centers with high cutting speeds, like the Makino a81, can produce a lot of cast iron fines in a short time period, posing special coolant-management challenges. In addition to chips, castiron machining creates fine particles in the range of 25 µm which can quickly become suspended in the coolant to create sludge.
For example, a 30-hp (22-kW) machining center can produce up to 25 ft3 (0.7 m3) of chips and 150 in.3 (2458 cm3) of sludge in 24 hr. Chips and sludge on typical machine installations can migrate through to the "clean side" of the coolant system, resulting in increased wear on tools, machine components, and workholding fixtures, necessitating more frequent and costly maintenance and lost production time. This also causes part-quality problems and shortens coolant life, translating into higher coolant-disposal and replacement costs.
Preventing migration of chips and fines back into the machining process is a critical element in the performance equation. Blockage of coolant distribution channels, including the system's pump, reduces coolant flow to tools and parts. Failure to properly flush chips from parts and workholding can result in premature tool wear, inaccurate tool compensation, and higher heat that can work-harden areas of the part. Eventually, the pump will cavitate, potentially burning out motors or wearing seals. Also, when chips and fines accumulate in the reservoir, to the point where their volume displaces too much of the fluid, the coolant temperatures begin to rise, resulting in evaporation and further quality issues.
The picture for Ansco was further complicated by the existing chip conveyor and coolant filter attached to the a81. Clogged with cast-iron sludge, the drum screen on the coolant filter would break, and the company would only find out about the damage when the coolant nozzles plugged or broke. This caused extensive downtime for cleaning. The time between cleanings was every three months, and each time the drum screen had to be replaced.
For a solution Ansco turned to Mayfran International (Cleveland). Mayfran supplied a MagSep Conveyor for the dedicated cast-iron application. With the MagSep magnetic drag (or scraper) conveyor, coolant and chips are directed to the magnetic surface before exiting the conveyor. The magnetic bottom pan attracts ferrous chips and fines, and the conveyor flights continually remove chips from the bottom pan while clean coolant exits the tank.
This action results in coolant clean enough for many machining operations, but for this application Mayfran added an AT-Cleaner Coolant Cleaning system. The AT-Cleaner, a media-free unit, further cleans the coolant, removing fines and maintaining a nominal 10–15 µm level in the coolant, which in turn promotes longer tool life, less maintenance on machines and workholding devices, and greater part quality. Plus, the ATCleaner is maintenance-free, requiring no media filters to change and dispose of, resulting in lower costs and more spindle uptime. An easy-to-clean holding tank, separate from the clean tank reservoir, accumulates the sludge deposits discharged by the AT unit.
Ansco eliminated eight days of downtime totaling 320 labor hr, and eliminated $8000 in drum screen replacement costs every three months, achieving rapid payback.
"After taking delivery of our first MagSep system, we were able to get hard numbers on what we are saving. The savings come from direct cost of repair parts, reduced downtime and reduced coolant costs," Thomas Cook, project manager, says. "Switching to the MagSep paid for itself in less than two years, just in repair parts. The savings in downtime and coolant costs fall right to the bottom line as profit."
Ansco management plans to add a Mayfran MagSep with AT-Cleaner to its next machine.
For more information on Mayfran International, go to www.mayfran.com or telephone 440.461.4100; for more information on Makino Inc., go to www.makino.com or telephone 513.573.7200.
Deburring Takes the Heat
Heat sinks may be used in any product that generates heat. A heat sink's purpose is to dissipate that heat. in any product that generates heat. As a result, heat-sink applications cover a wide range of products and industries, including electronics, appliances, motor vehicles, airplanes, and even the space shuttle. Heat sinks may be very small, very large, or any size in between.
Heat sinks are manufactured in many configurations from a number of metal alloys. Most alloys used for this purpose, however, are soft metals like aluminum. Another feature that most heat sinks have in common is that they are extruded, and extrusions have burred ends where they are cut to the needed length.
Since 1981, Tucker Engineering Inc. (Peabody, MA) has specialized in machining and fabricating heat sinks. Although the company is a custom job shop, it has carved out a niche manufacturing any type of heat sink imaginable.
For the first quarter century, Tucker deburred heat-sink ends manually. That involved presenting the heat sink to a grinder equipped with a wire brush. The operator had to be skilled at presenting the part at just the right angle. He also had to be careful not to deburr too deeply into the metal, because the wire medium could scratch the surface, resulting in an out-of-spec workpiece.
Manual deburring was time-consuming, expensive, and labor intensive. Using wire could also result in overheating, which could distort the workpiece.
"The Abtex deburring machine has cut our wirewheeling time for heatsinks by 200–300%," says Donald Tucker, president. "The average time to wirewheel by hand was between one and two min per heatsink. With the Abtex machine it now only takes 30 sec maximum per heatsink. The machine has also taken the physical labor out of this tedious process and every part comes out uniform and the same in appearance. My deburring department loves this machine and uses it every day for deburring our heatsinks and extrusions."
Tucker first became aware of Abtex Corp. (Dresden, NY) in 2001. Abtex manufactures deburring brushes composed of abrasive filaments embedded in the company's proprietary polymer backing. The flexible abrasive filaments make the brushes well-suited for deburring applications. Abtex Systems Group also manufactures brush deburring machines designed for specific applications.
Abtex has manufactured abrasive filament brushes and deburring systems since 1980. Abrasive filament is composed of heat stabilized nylon, which has been co-extruded with an abrasive grit. The grit is impregnated throughout the filament, as well as exposed on the external surfaces. As the filament wears, new abrasive grit is exposed. The filament is, in effect, selfsharpening. Abrasive action occurs on both the tip and the sides of the filament. Slower rpm rates allow the fiber to strike and wipe against the targeted surface much like a flexible file.
As Tucker's business grew, deburring became more of a bottleneck in its manufacturing process. In 2008, Abtex contacted Tucker and offered an in-stock machine designed specifically for deburring the ends of aluminum extrusions. This offer prompted President Donald Tucker to acquire a semi-automatic, single-end return-to-operator deburring system. One 12 or 14" (305 or 356-mm) disk brush thoroughly deburrs profiles of any shape. Part penetration into the face of the brush is minimal and accurately controlled. This concentrates the abrasive action only on the end of the extrusion, eliminating any marking of the lateral surface.
The Abtex system can be operated with only basic training. The operator loads one, or several, extrusions onto the transfer table and presses two palm buttons. The table carries the extrusion end through the face of the brush twice, taking advantage of the multi-directional wiping action of the disks' filaments. The operator then removes the part and turns it to repeat the process on the other end.
Tucker Engineering has increased heat sink productivity substantially with the Abtex end-deburring system, and improved quality control with the conversion to abrasive-filament deburring brushes.
For more information on Abtex Corp., go to www.abtex.com or phone 888.662.2839.
This article was first published in the January 2010 edition of Manfacturing Engineering magazine.