Why is measuring uv rim coat coverage important?

UV base rim coat lacquer is applied to all metal beverage cans manufactured worldwide on both steel & aluminium. The lacquer application helps to extend the shelf life of consumer products and improve the can's mobility during the manufacturing & filling process. Cans with poor or missing base rim coat application typically cannot be reworked / recovered and have to be scrapped.

What are the advantages of automatic rim coat inspection?

From a quality perspective, the Z312 vision system replaces the manual task of physically checking the cans, saving labour time and increasing operator productivity. Automating UV rim coat inspection helps reduce customer complaints and isolations, and scrap through defective product.

The Technical Details

Rim Coat Percentage Coverage Feature:

Each can variant is independently set up with the essential area where lacquer is required and identified, this ordinarily being the area on the can which comes into contact with the surface for mobility, we refer to this as our "area of interest".

The raw image is then processed by the software and a percentage coverage area for the area of interest is reported. By setting part nominal values for this feature, a classification of "pass" or "fail" can be achieved. 100% = Full Coverage - 50% = Half Coverage.

Images are displayed on the screen for operator evaluation or as part of the batch report.


To complete the above, there is no calibration / qualification method required for the camera module. Each component is set up individually using the GaugeXplorer part setup parameters found within our diagnostic screens. There are various settings which are available for operator adjustment in order to customise the lacquer inspection to the process.

Modular Measurement Options

Additional ISG Traceability:

The Z312 vision system has the additional option of ISG traceability, available for both inline and batch loaded gauging where internal lacquer spray gun recognition is required.

Rim Coat Thickness:

You may have a requirement to control the level of lacquer being applied to the base of the can, in this case Torus recommends the Z340 enhanced coating analyser featuring lacquer thickness measurement. Thickness inspection can be completed at selected points around the base of the can to provide lacquer distribution results, and identify thick and thin points of application to ensure there is no under and over application.


Designed with flexibility in mind the Z312 module can be integrated into any new or existing Torus gauge, or alternatively supplied as a standalone system. The flexible module boasts multi size capability with no change parts allowing the system to be located anywhere on the shop floor.

Screen/Results images of pass/fail rim coat and ink dot / character recognition

100% Rim Coat Coverage

65% Rim Coat Coverage


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