Knockout punch

Punched and tapped parts are stacked on a pallet to be delivered to the press brake area for bending. A finished part (after bending) is shown on the left side of the stacking table for illustration purposes.

This is an application destined to stay in the U.S. It's a large, heavy-gauge, complex part delivered in large volumes on an as-needed basis to a major producer of computer server systems in Silicon Valley. Sanmina-SCI, Fremont, Calif., and Sun Microsystems partnered on the plan that ensured the volume necessary to justify investment in a new production process, just as the computer and telecommunications sectors were leading the way into recession.

Today the system used to produce rails for Sun's large servers is a key factor in Sanmina-SCI's competitiveness when it comes to this and similar applications, and the company is firmly positioned to leverage the benefits of its investment in the technology well into the future.

Ed Peterson, Sanmina-SCI's director of quality and manufacturing for the Enclosure Systems Div., recalled a recent emergency that the company could not have handled in the past. "We learned on a Saturday morning that we needed 10 completed chassis that day," he said. "We had them formed, plated, assembled, and out the door that day. It wouldn't have been possible without this system. The tapping requirements alone would have had us tapping holes at 6 o'clock that night."

The rails Sanmina-SCI produces for Sun have a complex series of punched geometries, along with 228 additional holes that must be tapped, 114 along each side. The part also requires coining and countersinking operations and stamping of numeric locator station numbers that Sun uses when incorporating the parts into its assembly process for building server units. The rail itself is fabricated from 1/8-inch steel. It's 5 feet long, about 1 ft. wide, and weighs 35 lbs. Sanmina-SCI supplies six different configurations of this part.

The complex, long, narrow configuration of this server rail, coupled with the need to tap 228 holes and high-volume production runs, drove Sanmina-SCI to purchase the progressive punching and tapping machine to achieve higher productivity and efficiency.

In the past, according to Bill Armstrong, Sanmina-SCI's manager of fabrication, the part was fabricated from steel blanks, which were run through a 33-ton, 58-station turret punch press, followed by tapping and countersinking secondary operations and, finally, a press brake bending stage. Tapping all those holes was a significant bottleneck. Depending on the part, typical production time was 15 to 24 minutes per part, the majority of which was spent in the tapping operation. Setup and changeover times also were somewhat lengthy.

To satisfy Sun's need for 50 to 60 completed units per day with multiple part variations, the company had to find a better way.

Riding the Rails

The company turned to a Flexipress progressive punching and tapping system supplied by Dimeco Alipresse of France. The self-contained, coil-fed system includes a double uncoiler that enables loading one coil as another is feeding the system. Steel from 5,000-lb. coils is fed through a straightener and servo roll feed onto a 9-ft. by 3-ft. bed, where it encounters a set of punching tools and a tapping station that punch the part and tap the holes before cutting it off and ejecting it into a stacking unit. The unit stacks finished parts onto pallets ready to be delivered to the bending operation.

The system has fully automated the punching and tapping of server rails, eliminating the bottleneck created by the tapping operation. It also performs the coining and countersinking operations, as well as the stamping of the numeric locator stations.

Automating the tapping operation proved to be the critical advantage.

This Flexipress line installed at Sanmina-SCI in Fremont, Calif., reduced the cycle time for producing the server rails the company supplies to Sun Microsystems.

"One of our biggest challenges was tapping the holes," Peterson said. "This has dramatically reduced our processing time, and the savings on the tapping alone were the main advantage. But it has also reduced labor, part-to-part variation, and overall cycle time."

A sophisticated control system drives a tool selector that enables the company to use one set of punching tools to produce the six part variations the customer requires. Four different dies are used for the six configurations. Every tool is equipped with a sensor that can shut down the system in case problems arise. The system completes the entire punching operation, including tapping 228 holes, coining, countersinking, numeric locator station stamping, unloading, and stacking onto pallets, at the rate of about two minutes per part. This represents a total cycle time reduction of more than 90 percent in some cases.

According to Armstrong, three key elements converged to unleash the advantages of the system.

"The efficiency and productivity kicked in because of the complexity of this part, because it is a long, narrow part that fits this system well, and because we have the high volume that can initiate the high production rates that are possible," he said.

The system also can be adapted to a variety of long, narrow parts and can accommodate any tooling configuration necessary, Armstrong added.

"We looked at larger stamping machines and some of our existing stamping capabilities," he said. "But the advantages this system offered us were tailored to this application and gave us the flexibility to adapt the system to future requirements."

Another benefit the system offers is its programmable feed rate, which allows the progression of the part through the process to be varied, making it well-suited to handle future complicated parts.

Finally, the self-contained system boasts a narrow footprint, less than half that required by the larger conventional equipment that was considered for the application. In fact, it already has been relocated within the company's Fremont facility, a move Armstrong said was very easy.

This automated tapping station proved to be key in eliminating a secondary operation and reducing processing time.

Flexible in Fremont

Sanmina-SCI's Fremont operation is a 200,000-sq.-ft., state-of-the-art facility specializing in low-, medium-, and high-volume production of complex parts related to chassis, high-end data cabinets, and tubular frames. The company dedicates 12,000 sq. ft. to new-product introduction and offers high-level engineering capabilities to its customers in the telecommunications and computer systems sectors, such as Sun Microsystems, Cisco, Nortel Networks, and IBM.

The company is equipped to do full-scale chassis assembly, including riveting, welding, and hardware insertion. It also takes on subcomponent assembly of fan trays, blower units, power supplies, and power distribution units, as well as hardware integration for center- and backplanes, cabling, door kits, and mounting kits.

The company performs punching, bending, stamping, laser cutting, and robotic welding. For its punching operations, the company has 13 Amada turret punch presses, five automatic loader/unloaders, an Amada Apelio III punch/laser combination, and three FabriVISION® automatic optical inspection machines. In the bending area, the company has 27 Amada press brakes up to 135 tons in capacity and three Amada robotic press brakes. Three 150-ton Komatsu presses and a SEYI 66-ton press perform stamping. A Mitsubishi multifunction laser shares laser cutting loads with the Apelio laser combination machine. For tubular frame applications, the facility uses two robotic welding booths, 10 gas tungsten arc welding (GTAW) booths, six resistance spot welding machines, and various custom fixtures. The company also has an automated painting system with five-stage, inline washing; a phosphate wash booth; inline powder coating booths; and offline wet paint and powder booths.

Complementing all this hardware are high-level engineering and quality systems, including failure mode and effect analysis studies and process automation projects encompassing "greenlight tracking" of NC turret punch presses and robotic press brakes, lights-out automation, and offline press brake programming. The company is fully engaged in Six Sigma Green Belt training and has 11 certified Green Belts and a Master Black Belt at its Fremont location.

An online corrective action database connects multiple Sanmina facilities in the U.S., China, and Mexico. Any problem a customer reports is entered into this database, initiating an automated corrective action procedure, which, if not executed within a specific time frame, results in an escalating, automated e-mail alert sequence that informs responsible parties all the way up the chain of command, ultimately reaching corporate headquarters. A similar system is in place to monitor the production lines, processes, and equipment on the manufacturing floor.

The company is ISO 9001:2000-certified and has TL9000 registration, maintaining a continual internal audit to TL9000 standards. Supplier performance is monitored through a centralized supplier management system, also connected across multiple locations, involving quarterly scorecards, supplier audits, and annual supplier risk assessments. The company's different facilities in many cases use common suppliers, and the online corrective action database that can instantly alert all facilities is particularly powerful if one of those suppliers has a quality problem.

Finally, all the company's processes are statistical process control-monitored and include quality goals and yield charts for every department, as well as monthly process capability quality reports. Total defective parts per million (DPPM) is measured on an hourly basis, and in the event a process exceeds its upper control limits, the automated corrective action system kicks in, sending e-mail alerts to the appropriate individuals.

The system even sends text messages to Peterson's cell phone.

Group Publisher Scot Stevens can be reached at scot@thefabricator.com.

Sanmina-SCI Corp., 2700 N. First St., San Jose, CA 95134, 408-964-3500, fax 408-964-3636, www.sanmina-sci.com

Dimeco Alipresse, BP. 1163, Besancon, France 25480, +33-3-81-48-38-00, fax +33-3-81-48-38-28, www.dimeco.com

Sun Microsystems Inc., 4150 Network Circle, Santa Clara, CA 95054, 800-555-9786, www.sun.com