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Case Studies > Vision Solution to Inspect Food Jars

Vision Solution to Inspect Food Jars

A vision solution designed and installed by Industrial Technology Systems (ITS) has allowed a major food industry manufacturer to ensure trays of food jars reach the retailer without mistakes.

The company produces a range of sauces that are machine packaged and film-wrapped on cardboard trays.  A vision inspection system was required on the main conveyor line to check that the correct number of jars were present on each tray, and detect and reject jars with missing lids, incorrect lids, missing jars and missing film.

The trays for inspection are in three different pack sizes and travel down the line at a maximum speed of 35 trays per minute for the smallest tray, and 18 trays per minute for the largest.  Not only did the food manufacturer require a solution that was accurate at these speeds, but it had to deal with three varieties of jar in two heights, with different coloured lids.

The fully integrated inspection system that ITS provided uses a Cognex In-Sight® 1100 colour camera loaded with the PatMax® pattern finding tool for locating the lids, a Colour Histogram tool to check the lid colour, and white LED lighting to illuminate the field of view.  The camera is pre-configured with a series of job files, each of which have a set of vision tools to perform the necessary checks for a given tray size.  Cognex VisionView is used to select the required product type and jar lid colour, and provides real time inspection images.

To detect a missing jar or lid, the PatMax pattern recognition tool quickly and automatically distinguishes between the physically similar jar lids of different colours, and when used together with an additional colour tool, also detects where there are incorrect lids.  The same colour tool detects where film is missing from the tray.  Trays with one or more failures are automatically pushed off the main conveyor onto a locked reject conveyor.

The camera is housed in a Stainless Steel Enclosure to protect the camera during clean down operations, and diffused lighting from two white linear lights on either side of the conveyor are used to scatter the light off the shroud’s internal walls to evenly illuminate the jars’ lids below the clear plastic flow wrap.

The Cognex In-Sight 1100 colour camera’s 640 x 480 resolution and 6mm lens provide a generous 325 x 244 mm field of view for the vision system; the shroud’s height of 600mm allows cable clearance and a further increase in the field of view by 20mm.  

The camera is connected to the VisionView via Ethernet and all job files are stored in non-volatile memory within the camera.  The camera configuration can either be backed up to a laptop or a USB key fitted to the VisionView, and a filmstrip set up on the camera can display a limited number of the most recent images for diagnostic purposes.

The Cognex In-Sight 1100 colour camera was chosen because its compact size makes it ideal for a food packaging line where space is at a premium, and its robust manufacture provides the client with the reassurance that running maintenance is very low.

Because no external PC is required for this inspection process, costs are kept down and staff training is at a minimum because the inspection process is straightforward to operate.

Other benefits to the manufacturer are that they are quickly alerted to any problems because of the automatic transmission of the pass/fail results, and the need for operator intervention for product fails is removed because of the automatic reject mechanism.

“The client was extremely pleased with the vision inspection system we designed and installed for them,” Business Area Manager Graham Ives said.  “The Cognex system we put in represents outstanding performance, value for money and guaranteed results.  Their return on investment was immediate.

“The correct number of jars are now in each tray, correctly packaged, and the food manufacturer’s good reputation is maintained with retailers and customers.” 

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