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July 12, 2000

4 Min Read
Vision system eliminates hangups

When Cascade Engineering began producing interior door panels for customer JCI, operators found that the parts had a few hangups. "Because of the geometry, panels would hang on the tool even after the ejector pins retracted," says Paul Rugg, technical services manager at Grand Rapids, MI-based Cascade. As a result, the mold would close on the part, causing tool damage and downtime. Fail rates hovered around eight or nine parts per shift, with production rates for the six-day per week, three-shift operation reaching 6000 panel sets per week.

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Core and cavity sides of this $250,000 mold, property of GM, are monitored continously for part presence. The molded parts are interior door panels for the Chevrolet Malibu.


"We were spending $3000 per month on tool repairs and dealing with numerous delays while trying to meet production quotas. Changing the design of the door panel was not an option, because these parts were being made for GM’s current-model Chevrolet Malibu," Rugg says. "To solve the problem, we looked at vision systems that could keep the mold from closing if a part was stuck after ejection." 

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Tool wear data is extracted by the vision system, which will allow Cascade to design a preventive maintenance system based on the results.

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Using the TCP/IP Ethernet communications of the DVT Series 600, engineers can directly access the vision system from their desks. The system prevents mold closure if a part is not properly ejected.

Vision therapy
Rugg wanted to maintain automation and reduce the amount of time operators needed to keep an eye on the process. He found the DVT SmartImage Sensor, and installed the system on the 1760-ton Cincinnati Milacron dedicated to molding the panels. "Once we put the sensor [Series 600] in the machine and allowed it to start checking for part presence, we saw our fail rate go right down to zero," he explains. "It saved the tool repair costs, and let us allocate another $30,000 worth of annual labor costs because the press now requires only one full-time operator instead of two." Currently, Cascade produces 900 panel sets/day. 

The vision system is mounted facing the mold. Existing metal-halide lights provide ample illumination to determine whether the part has cleared the mold and if the ejector rods are properly retracted following each stroke. 

The system takes a picture when the tool opens. If it sees a part in the mold, it prevents the tool from closing, the press is taken out of continuous cycle, and the operator is notified to correct the problem and restart the process. "Form factor and size were very critical as to where we could mount it," explains Rugg, "and the ability to use existing light saved us a lot of additional installation time and cost." 

According to Rugg, the system has also cut down on flash. "The sensors measure a certain part of the ejector pins, which sometimes do not retract fully. They may stick out partially, about .020 inch, upon retraction. If that happens, the vision system won’t let the tool close." 

This eliminates the flash and bumps that were a problem previously. To assemble the door panel, Cascade takes the part and applies vinyl with adhesive. Before, when the tool flashed, operators had to trim the part, and chunks of flash would get under the vinyl. "That’s no longer an issue," he adds. 

Cascade also uses the system to measure other variables. For instance, one sensor checks the conveyor for parts being sent for vinyl application. If the operator falls behind, the system holds the mold until the operator, machine, and conveyor are synchronized. 

Rugg says he will soon use the vision system to compile a historical data chart on tool wear. "Each image has data. We then extract the data to create a preventive maintenance program when tolerances start reaching critical levels." 

The DVT system does not require a secondary dedicated computer. Its own internal CPU can communicate via TCP/IP Ethernet, allowing Cascade to access it through its internal network or the Internet. 

Contact information
Cascade Engineering
Grand Rapids, MI
Paul Rugg
Phone: (616) 975-4789
Fax: (616) 956-9492
E-mail: [email protected]

DVT Corp.
Norcross, GA
Michael Valverde
Phone: (770) 449-4960
Fax: (770) 449-3073
Web: www.dvtsensors.com
E-mail: [email protected]

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