Unilock Universal Clamping System Helps Boeing Achieve
Dramatic Reduction in Setup, Production Time

Unilock clamping chucks mate with clamping knobs attached to base plates, fixtures or directly to workpieces.

CAUBURN, WA—The Boeing Company engineers at the Fabrication Division plant here have achieved dramatic reduction in setup times and increased productivity by introducing BIG Kaiser Precision Tooling’s Unilock universal clamping system.

In one operation, Boeing cut to 20 minutes a large gantry fixture changing operation for airplane flaps that used to take nearly two hours. Another fixture change for smaller airplane parts (trunnions) that used to take an hour is now completed in seconds with Unilock.

In Boeing’s application, a series of Unilock clamping chucks mate with a series of clamping knobs to hold the fixture or workpiece. Each chuck has up to 11,240 pounds of clamping force and achieves repeatability of .0002" or better. It provides a solution for two of manufacturing’s toughest setup problems: repeatability of location from one fixture or workpiece blank to another and transfer of work from one machine tool to another.

Unilock clamping chucks are machined into the subplate and connected with air for simultaneous clamping or unclamping.

A Perfect Fit
“Boeing was finding it awkward to set these large parts on fixturing plates, then take them on and off,” says BIG Kaiser Sales Representative Steve Andrews, of A&I Marketing, Seatac, WA.

“We were able to streamline the system by mating Unilock receivers with Boeing’s own subplate. The real payoff was that the Unilock chuck’s knob fit right into Boeing’s fixturing plates, saving the cost of buying new pallets,” Andrews says.

Andrews brought in a BIG Kaiser workholding specialist for a Unilock demonstration. Boeing engineers were impressed with the speed of the Unilock change, its repeatability, accuracy and ease of use and, even more important to Boeing, the ability to build their own fixtures and mating receivers with standard Unilock components. “It was much easier to implement than the system they had been using,” Andrews says.

In one operation, Boeing is using the system in the machining of flaps for the 777 commercial airliner. It is a bonded assembly that involves machining one half, then the other, and fastening them together. “The old way, it took us two hours to change out the fixtures. With the Unilock, we just clean off the fixtures and put them back on the machine. It takes about 20 minutes,” says Steve Martin, Boeing Process Engineer.

Another operation involves machining trunnions for the 757. “The parts require seven different media for roughing, finishing and other operations. We flip parts over to work on both sides and use several different tools. Unilock gives us precise locating in an instant, 100 percent of the time. It always works. The center locator is precision ground and uses a diamond pin. We know that’s where it’s going to be every time,” says Miles Olson, Boeing’s NC Programming Manager.

Hit Cycle Start and Cut
“We have long run times on these parts, anywhere from 45 minutes to four hours. We have six fixture changeouts per shift. Unilock has cut our clamp and unclamp time. However, it’s not just the speed that makes a difference, but accuracy and repeatability. When we clamp the fixture, we’re done. We hit cycle start and cut the part, knowing we are getting accurately machined parts with side A and side B matching precisely,” Olson adds.

Fixture ready for clamping, with clamping knobs mounted to underside, pulled into each chuck with over 11,000 pounds of force.

“We are using the Unilock Riser Plate to hold fixtures for production parts on our 5-axis Makino machining center. We achieved a simultaneous nesting surface for the fixture to the riser surface and Unilock chucks within .0002”. Tooling pin locations on the first fixture we are running probed within .0002" on the first check. The fixture lifted off the riser plate, then re-clamped and cycled back into the machine. The tooling pins probed within .0001" of location,” explains Olson.

“We have reduced fixture clamp and unclamp time for this pallet to zero. It also eliminates the need to re-adjust the fixture location on the pallet to get it within our fixture probing tolerance. Fixture locating accuracy and repeatability are now under control,” he adds.

Boeing typically performs multiple operations—turning, milling, and grinding, for example—on the same workpiece, using several different machine tools. It usually has to meet close tolerances, plus or minus a tenth or two, Olson and Martin say. “Setup time was killing us. We might often take five hours for setup. On each operation, we would have to align and redefine work coordinates,” Martin says.

Setup the 'Black Hole'
Boeing needed a central datum for transfer of a single workpiece from operation to operation, machine to machine, to maintain the same position, moving it without losing the datum point. “When people talk about the ‘black hole’ in manufacturing productivity, we always hear setup,” BIG Kaiser Sales Rep Andrews says.

With Unilock, a workpiece reference location need only be established once. Alignments for the chuck are established from its center line, and they can capture electronically and keep data in the machine’s CNC program. They can run any fixture at any time. Unilock on a machine is like having a virtual pallet pool of fixtures ready to go. The system becomes universal throughout the shop, slashing machine setup time.

“Operations that used to take days are now completed in minutes or hours. The system gives us much more versatility to make our commitments,” Olson says. Boeing is expanding the system to additional parts.

Interchangeability in Fixturing
“The Unilock uses quick change to help manufacturers standardize the workholding process. It achieves interchangeability in workpiece fixturing the same as standard tool tapers and spindles have done in toolholding,” says BIG Kaiser Product Manager, Workholding Systems, Gerard Vacio.

A Boeing operator attaches an air line to prepare for removal of subplate, aided by clamped Unilock chucks.

The modularity of the Unilock system adapts to workpieces of virtually any shape or size. Zero point clamping chucks are available in different configurations for integration onto all types of machine tools, such as mills, lathes, grinders, and EDM, as well as measuring equipment such as CMMs. Unilock offers standard pallets in steel and aluminum, or customers can produce their own pallets by purchasing the positioning components. Position and clamping elements can also be mounted directly to workpieces or existing fixtures.

Key to gaining efficiency from the system is to incorporate the quick changeover features afforded by knowing the relative location of the receiver chuck and simply mating the preloaded pallet to it. Once the location is established, it will repeat for any subsequent process step that a workpiece will encounter. More process-intense workpieces reap the maximum throughput gains.