Vision system enables zero defects
Schneider Electric decided that vision was the only inspection solution.
By Ann R. Thryft, Contributing Technical Editor -- Test & Measurement World, 10/1/2009 2:00:00 AM
Schneider Electric's Osiswitch Compact line of limit switches are used in industrial automation and control equipment. From only 100 different components, the production line can create up to 2000 different product types, or “references,” each identified by an industrial reference code. Each product is composed of around 20 parts selected from those 100 components, which include mechanical parts and circuit breakers.
Although switches that are made from several different product types can look identical on the outside, inside there are many different sets of components and many different configurations of those components. The Osiswitch Compact limit switches are only 30x70 mm, and their subassemblies must be checked before they are enclosed within a body.
“We have to check many small parts on a product,” said Nicolas Charollais, marketing director for Schneider Electric. This is why, until recently, the company assembled these products by hand. It is also why the company used a simple control system—naked eye inspection—for ensuring that a customer got the right product assembled with the right parts list, he said.
“Although from a customer's standpoint the main benefit of these products is the fact that they are configurable, from a manufacturing perspective that configurability was also the main problem,” said Charollais. Products can have the same body, but the same external design can be associated with many different references, depending on which kind of contact is inside, along with other components and their configuration.
“At Schneider Electric, we focus on product quality at all levels of production,” said Charollais. According to customer feedback, the biggest problem with this product line was not quality or performance, he explained, but the fact that customers occasionally received a product that was slightly different inside from what the outside label stated. “In those cases, the product reference a customer ordered was not the one delivered, although it looked the same,” he said. Because of this, the Osiswitch Compact product line's customer return rate was around 100 parts per million.
When the company started a new product family in the Osiswitch Compact line, it also decided to implement a new control bench for that entire line that would reduce the customer return rate to zero parts per million, said Charollais. “But since the product itself isn't very expensive, we didn't want to make expensive investments in a new assembly line, so the system had to be cost-effective.”
Because the parts inside each product are so small and close together, and also because they look so similar to each other, inspection cannot be done by fiber-optic detectors. Fiber optics can only detect different mechanical shapes, and, in this case, those mechanical component shapes are too similar. Schneider Electric therefore decided that vision was the only inspection solution.
Cognex and its partner integrator Esox did a feasibility study for Schneider Electric and proposed a solution that allows complete assembly inspection of each component of the different products by analyzing the product's nomenclature. The nomenclature is the list of components or parts making up the product, which have to be recognized to ensure that they are the right ones for that product and that they are present in the assembly. The analysis is performed by the multi-image display function of Cognex's VisionPro software. This function makes it possible to recognize a part either from its shape or from the industrial reference code written on it via letters and numbers recognition.
| Read more articles from our October 2009 Machine-Vision & Inspection Test Report. |
The vision station is made up of two cameras and five LED light sources, plus a laser beam. The first camera, a high-resolution model (1600x1200 pixels), inspects the internal parts of the product and checks the industrial reference code inscribed on the contacts. The second, lower-resolution camera inspects the overall view of the product. Images are recorded in the inspection database and used to improve upstream manufacturing and prevent defects.
The lighting system also represented a serious challenge. Esox designed an optical system with a software tool programmed to operate according to exposure times. This system allows the lighting to be adapted according to each product reference, so several lighting variations can be called up in sequence, depending on which product family in the Osiswitch Compact line is being inspected, said Charollais.
Depending on the complexity of each product inspection, the system displays one or more images, up to 12, one per frame, on a single screen. The software processes each image, and the inspection results appear on each of these frames, labelled red (wrong part or part position) or green (correct part or part position), allowing the operator to rapidly visualize any problems.
Schneider Electric completed the system's fine-tuning at its facility in France and installed the first system at one of its production sites in Spain. After two weeks of further tuning and industrial tests for recognizing different product configurations, the production line was transferred to the company's manufacturing site in Batam, Indonesia.
This vision system allows fully automatic control of the manufacturing of Schneider Electric's Osiswitch Compact products. Because the system archives all statistics, all nonconforming defects can be monitored. This kind of control also means that inspected products are completely traceable.
“This system has helped us reach zero defects for this new product family,” said Charollais. “We now also have more flexibility.” If the company wants to implement a new product reference made up of existing parts the system knows, it takes only a few minutes. There are currently 600 product references for this new product family, with a potential of up to 1000.
“When we create a new reference, we might change only one part inside the product because a customer has asked for that particular configuration,” he said. Since the system can learn a new reference quickly and easily, Schneider Electric doesn't have to spend time creating new documents or training people for its inspection. “This lets us speed up the manufacturing portion of creating a new product,” said Charollais.
No related content found.
- 0 rated items found.
Datasheets.com Electronic Parts & Inventory Search
185 million searchable parts
- Part Number
- Description
- Inventory
- Products
- Manufacturers
View All Webcasts
