Engineering Research Center for Reconfigurable Manufacturing Systems (ERC/RMS)

ERC/RMS Reconfigurable Inspection Machine Installed on GMC Manufacturing Line

Today's automotive engine technology is extremely sophisticated and requires manufacturers to maintain exacting quality specifications to ensure optimum engine performance and reliability. Hence, manufacturers are increasingly employing in-line inspection stations to inspect critical part features on 100% of the parts. In-line inspection minimizes the chances of defective parts reaching the customer and facilitates process control and process improvement. The best applications of in-line inspection are those where the quality is highly unpredictable.

One example of such an application is the need for in-line surface porosity inspection systems. Surface porosity is caused by tiny voids or pits at the surface of machined castings such as engine blocks and engine heads. Surface porosity begins in the casting process when gasses are trapped in the metal as the casting solidifies, creating voids in the material. If the void is exposed during machining, it leaves a small pit (i.e., surface pore) at the surface. Although they are typically smaller than 1mm, surface pores can create significant leaks of coolant, oil, or combustion gasses between critical mating surfaces and cause severe damage to engines and transmissions. If such a pore is not detected, the consumer will have a noisy engine with shorter lifetime.

As an outgrowth of its Reconfigurable Inspection Machine project, the ERC for Reconfigurable Manufacturing Systems (RMS) at the University of Michigan developed a prototype machine-vision system for in-line surface porosity inspection of engine blocks and engine heads. The system utilizes a specially designed vision system to acquire very high-resolution (300 megapixel) images of the part surface. The high-resolution images are then analyzed rapidly to detect, locate, and measure pores. This technology is very important to engine manufacturers because of the difficulty in objectively measuring the sizes and location of irregularly shaped surface pores at production line rates.

In July 2006, this technology made a significant leap forward. General Motors Corp., an ERC member company, installed an industrial system for in-line surface porosity inspection of engine blocks in Flint, Michigan. The system is based on the technology developed at the ERC/RMS. The inspection system is integrated into the production line, and a conveyor moves engine blocks through the inspection station. Therefore, every part is measured within 15-20 seconds. By using this technology the manufacturer expects to prevent defective parts from reaching the customer and also to collect meaningful data for process improvement.

With this ERC/RMS technology the human inspector is able to do a more thorough job. Instead of trying to detect pores on every engine block at a rate of two per minute, the inspector now inspects the images of just those engine blocks on which a defect was detected by the automated inspection system.

To learn more about this topic:
Visit the Engineering Research Center for Reconfigurable Machining Systems technology transfer page at http://erc.engin.umich.edu/industry/tech_transfer.html

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Engine block moves into the inspection station.

An operator inspects the images of an engine block
in which pores were detected and makes the
intelligent decision as to whether the engine block
is indeed defective.

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Last modified: April 8, 2007