System airs out component-testing problems

System airs out component-testing problems

Testing oil pumps and other automotive components for their ability to hold and circulate high-pressure oil or water was a messy job at Metaldyne Powertrain/NVH Group in Middleville, Mich. The shop used motor oil, or, in some cases, a lightweight oil-base

Metaldyne tests and assembles automotive-engine front-cover assemblies using a special air-verification system from Weldun.

Testing oil pumps and other automotive components for their ability to hold and circulate high-pressure oil or water was a messy job at Metaldyne Powertrain/NVH Group in Middleville, Mich. The shop used motor oil, or, in some cases, a lightweight oil-based fluid such as automatic-transmission fluid (ATF) that, once at operating temperatures, dripped everywhere.

The situation raised housekeeping, environmental, and health issues. For instance, operators handled parts dripping with oil and were constantly flushing and cleaning the shop's recyclable shipping containers. In addition, ATF is caustic, and when heated to 200°F, mist boils off and hangs in the air, which irritates the skin, eyes, and throats of workers. To remedy these problems, the shop switched to a Weldun air-verification system for testing its components.

Besides curing environmental and housekeeping issues, air as a test medium is as much as 40 more sensitive than oil or ATF, according to experts. Plus, Metaldyne's air testing is faster, and results are immediately available.

According to Michael Zimanski, Weldun senior controls engineer, an air leak at about 10 psi at 25 cc/min equals an oil leak. With air verification at 15 psi, shops readily detect leaks in the 6 to 12-cc/min range. This, he says, is significant. The automated air-verification system Weldun built for Metaldyne includes 13 stations spread out in a rectangle measuring 60 40 ft. It processes machined castings and attaches a water pump, oil pump, thermostat, temperature sensor, and power-steering-pump-mounting bracket to them. While doing so, it tests and verifies all critical functions of the entire front-cover assembly.

Aluminum front-cover castings come from machining, and a pick-and-place device puts them on a window-frame pallet, which carries them to the first of three airverification stations. The first station tests casting porosity to ensure the three main internal cavities — the water and oil cavities and the timing-chain dead space — are isolated from one another and not leaking. It also detects any non-conformance such as parallelism or flatness resulting from machining. The second station checks for blockages in the internal passageways of the castings. High-velocity, low-pressure air (about 1 psi) pumps through the passageways, and back-pressure data verifies the presence or absence of blockage.

With the water pump and oil pump installed, the front-cover assembly enters the final and most complex air-verification station, the one that establishes functionality of the oil pump and complete assembly. Controlled, high-pressure compressed air ramps pressure up and down to check any activity deviation like an aberration in flowrate.

"In addition, all air-verification data plays a critical role in warranty cases," says Jay Fluegal, engineering manager at Metaldyne. "When an engine fails in the field, seizes up, or throws a bearing, one of the first things the OEM looks at is the oil pump. Invariably, the OEM comes back to the supplier for confirmation that the pump was a good product. In cases like this, we can send it all the verification data that confirms the pump was operating to spec when shipped."

Weldun International Inc. Bridgman, Mich.

On-the-fly jet-engine blade inspection

A jointly developed system from LMI and Oryx accurately inspects jet-engine blades on-the-fly at high speeds. (photo courtesy of Rolls-Royce)

To optimize jet-engine performance and ensure safety, small-aircraft operators rely on overhaul facilities to inspect, replace, and regrind hundreds of small, stainless steel and Inconel blades in the engines. And, typically, overhaul facilities manually inspect blades to indicate the length and position of each within the rotary intake.

This labor-intensive task involves fastening the engine to an inoperable grinder, manually indexing the rotary intake, and measuring each blade. Manually turning and positioning each blade makes achieving consistent accuracy difficult. To replace such manual measuring for overhaul facilities, sensor company LMI Technologies and systems integrator Oryx Systems, Charlotte, N.C., developed a system that accurately inspects blades on-the-fly at high speeds.

The system features a noncontact Laser Twin Sensor (LTS) from LMI and software and signal-processing hardware from Oryx. That company also provided standard off-the-shelf designs and fixturing along with a sensor-software package.

For automating the inspection process, Oryx positions the LTS at a diagonal location below the rotor. The laser measurement sensor emits a laser beam that the blade surface, reflecting a spot through twin imaging optics and onto two position-sensitive detectors. As the rotor spins, the sensor measures each blade-tip length from the centerline of each wheel. It measures at 200 msec with a tolerance of ±0.005 in. and a resolution of ±0.0001 in.

Signals from the sensor travel to the Oryx PC-based controller. Its software reports the readings for all blades in each rotary intake along with high and low readings. The LMI/Oryx system also automatically monitors each blade position within the intake to ensure a precise fit.

The system then reports the average measurement for each stage, so users know which blades to replace or reposition. After replacement, the system indicates whether or not blades are properly positioned within the intake and ground to specification.

LMI Technologies Inc. Southfield, Mich.

Company arms welding fixtures

A FaroArm mounts onto the tooling frame of a Lindgren Automation welding carousel and lets operators quickly measure positions of blocks and pins that hold parts for welding.

Lindgren Automation Inc. of Concord, Ontario, develops custom fabrication machines, and one of its specialties is carousel/Ferris-wheel fixtures that hold parts for MIG/laser/spot robot welders to weld into single structural pieces. The problem with high-speed welding, however, is that once parts are heated, they distort around the hot zones. It's Lindgren's job to build fixtures that anticipate this distortion, so parts come out "on the nominals." But one job forced the shop to scrap its normal approach and incorporate a portable CMM.

The pivotal job was building carousel fixtures for two lines at Van-Rob Stampings in Toronto. These lines weld cross-car (dashboard) beams for the redesigned Ford F-150. To reduce fixture-development time, Lindgren and Van-Rob engineers studied how welding affected sample material similar to that used for the beams. Using a FaroArm portable CMM on the test pieces, Lindgren engineers documented distortion patterns for welded shapes, varying weld spacing, timing, and clamping position. They considered thousands of variables and built a database of distortion tendencies as they measured the changes in part dimension.

From this database, the shop made the first carousel. It included two mounting spots on each fixture frame for attaching the FaroArm, which would monitor the process on the production floor.

The FaroArm is an articulating measuring instrument that measures any point within its spherical reach. Its measuring stylus moves with 6° of freedom to touch points on surfaces, cavities, and in remote spots within machines.

During initial parts trials, Lindgren engineers tweaked locator blocks and pins until achieving nominals (250 measurement points). They then measured the fixture with the FaroArm, froze these signature dimensions, and saved them in the FaroArm's CAM2 software. From this file, they constructed and set up the additional machine stages.

"Concurrent engineering let us shrink the time needed to get the second and third stages of these lines in operation," notes Ed Wazny, project manager for Lindgren. "Because we knew these settings produced parts at nominals on the first unit, the others would follow suit at the same settings." Also, with the predictive data acquired using the FaroArm, the shop eliminated months of startup testing.

Faro Technologies Inc. Lake Mary, Fla.

System provides riveting solution for process monitoring

The PC-AMS monitoring system from Promess eliminates manual post-process inspection and provides traceability (100% verification) for automotive ball-joint assemblies.

To improve quality and reduce process costs, a major Midwest automotive-parts supplier has installed automatic process monitoring on its ball-joint-riveting system. The monitoring system eliminates manual post-process inspection and provides traceability (100% verification) of each ball-joint assembly.

Ball-joint assemblies hold three rivets that are simultaneously pressed in by a single hydraulic cylinder. Verification of each rivet is mandatory, as well as the assembly's integrity, because rivets sometimes run too long or short, or may not be there at all. They can also be too hard or soft and not pressed to the correct depth.

What the shop uses for rivet verification is a Promess PC-AMS monitoring system based on signature-analysis technology. The system performs force-versus-distance signature monitoring, multiram monitoring, and integral data acquisition for individual part histories.

Promess bases its signature-analysis technology on the concept that once the qualities of a known good operation are identified, that operation is "cloneable." It does so by monitoring the qualities of subsequent operations and comparing them to the signature of the known good process.

Signature analysis not only detects bad assemblies, it frequently pinpoints causes of an out-of-signature event. The exact shape of the signature provides information about the individual parts being assembled, which serves as control input for other processes. Process signatures are what indicate if a rivet is too long, short, hard, or soft.

Three separate load cells, mounted into the shop's tooling, independently measure force applied to each rivet, while a single position transducer measures ram travel. When combined and analyzed in the system's control unit, these measurements present an accurate picture of assembly quality, and that of each rivet, in real time.

Promess Inc. Brighton, Mich.

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