AUTOMOTIVE SUPPLIER ACHIEVES PERFECT QUALITY WITH LOW-COST MACHINE VISION

Ice Industries' (Sylvania, OH) is an international provider of large format, deep draw, high tonnage metal stamping, welding, and assembly utilizing steel and other metals. As a world-class supplier, the company serves a balanced customer base that includes the appliance, HVAC, refrigeration, off highway, fire safety, turf and garden and automotive markets. Manufacturing capabilities include highly automated processes that provide high volume stampings using multiple tooling types and equipment capabilities.

Ice Industries heavily stresses being a proactive supplier to the customer. This has led to the implementation of numerous process improvements, such as press chutes fitted with photoelectric counters/measurement devices and thermal sensors for parts exiting the welding stations.

An automotive original equipment manufacturer (OEM) recently added a welded nut to a stamped metal frame rail produced by the company's Deerfield Manufacturing subsidiary (Mason, OH) as part of a poka yoke machine vision system that continually focuses on providing world-class quality to its OE customers.

If the customer were to receive a frame rail without a nut, Ice Industries would be subject to substantial penalties, including 100 percent containment and inspection of all product until root-cause corrective action has been approved by the customer and implemented by Ice . . . not to mention the blemish on their quality scores.

To prevent this from happening, Ice Industries installed a Cognex Checker 202 vision sensor that inspects each part for the location, presence or absence of the nut. If the nut is not present, a cylinder will eject the part into a reject bin. Engineer Phil Kautzman of Ice Industries programmed the vision sensor using the One-Click Setup method.

"The vision sensor has been 100 percent effective," said David Randall, a manufacturing engineering manager for Deerfield. "If this system prevents one bad part from reaching the customer the savings from this would equal more than the total cost of the vision sensor. It has not allowed a single bad part to reach the customer."

Four stamping operations are performed on the front rail in two manually loaded presses with two dies each at a production rate of 1,875 per 7.5-hour shift. Soon after the customer made the change, Deerfield designed and built a welder to add the nut to the stamped part after the stamping operations are completed. The traditional approach would have been to have an operator inspect each part for the presence of the nut as the parts are packed.

"The problem with manual inspection is that it is never 100 percent accurate," Randall said. "People have a tendency to get tired, bored, and start thinking of other things near the end of their shift. Our philosophy is to eliminate even a single bad part."

SELECTING AND PROGRAMMING THE VISION SENSOR
Deerfield management decided to take a look at machine vision. The company had frequently utilized automated inspection systems, such as proximity switches, but their experience with visions systems was more limited. "We have often found the costs of machine vision systems to be prohibitive," noted Randall. "Then one of our engineers found the Checker on the internet. Besides the low cost, we liked the fact that Checker is so easy to use. We ran through a demo on their website and in just a couple of minutes programmed Checker to inspect a sample part."

Deerfield contacted a local distributor, Crescent Electric Supply Company (CESCO), which came in and reviewed the part and provided recommendations on how to perform the inspection operation. CESCO recommended the Checker 202 vision sensor, which integrates lighting, optics, camera, processor, and input/output (I/O) in an industrial IP67 housing. The Checker 202 includes presence sensors that verify features are present and measurement sensors that verify features are the correct height, width, and diameter. When the user clicks on "new program," the software provides a wizard that guides the user step-by-step through the programming process. The Checker 202 also includes an industry standard ladder logic editor that can be used to customize the results of the inspection.

"Crescent provided an overview of how to program Checker and Kautzman mastered it in a week," Randall said. "Phil is now our vision systems expert, and he has trained the fabrication people to make changes to the program when needed." Kautzman programmed the inspection operation by first positioning the camera in the station so that the area to be inspected was visible on the screen. He connected a laptop computer to the camera and loaded the setup software, which shows the camera image on the screen. Kautzman drew a square around the nut to call out the feature being inspected. He then replaced the part with one that did not have the nut present. Checker's One-Click Setup feature automatically creates a sensor, learns the features attributes and sets the appropriate pass/fail criteria.

Kautzman interfaced the camera with the PLC running the welding system. He configured the camera so it is continually looking for a hole pattern on the frame rail on the conveyor carrying parts away from the stamping and welding line. When the camera sees the hole pattern, it then runs the contrast sensor mentioned above.

QUICK AND EASY CHANGEOVER
Deerfield has six different models of this frame rail. To change the Checker over only requires the operator to pull up the proper program within the system. There is no need to move the position of the camera or fixture. The time it takes to change the Checker over is less than one minute.

VISION SENSOR HAS NOT PASSED A SINGLE BAD PART
Checker inspects assembled and welded parts against a digitized model as the parts move on the conveyer at a speed of 30 feet per minute. If the camera sees the nut, then it does nothing and the part continues traveling to the good parts bin. If the camera does not see the nut, it sends a signal to the PLC and the PLC actuates a cylinder that knocks the part off the conveyor and into a reject bin. The reject bin consists of an alarmed cage that can be accessed only by the setup person. Data is collected on all inspected parts, which can later be utilized to improve the assembly and welding process.

"We adjusted the vision sensor with the intention that it will not pass a single part without a nut," Randall said. "Since the fine-tuning of the inspection parameters were completed, Checker has detected every bad part. Our quality procedures require sending a bad part through the vision system every hour just to make sure it is working. It's also important to note that Checker has performed without any downtime in the harsh stamping environment. When we decided to implement Checker, we brought the customer in to review it. His only questions were about how he could implement similar machine vision systems in his own operation. "

"Deerfield is already working on another machine vision application," Randall added. "This new application is designed to inspect a welded part to ensure the weld boss is present and in the proper orientation. This system will be more complex and we will probably use a more powerful vision system such as the In-Sight® vision system, which offers many different inspection tools that enable it to inspect for the presence of and measure a very wide range of features.

"The bottom line is that every automotive supplier knows what one rejected part can do and also knows that manual inspection runs the continual risk of errors. Our philosophy is to address 100-percent root-cause corrective actions on issues. This vision inspection system meets that goal . . . it is the next step in process control. We will be expanding our use of machine vision in the future to ensure that we continue to exceed our customers' expectations."

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Ice Industries, iceindustries.com

Cognex, www.cognex.com