There are several means of seam inspection generally established by each individual or manufacturer, such as making use of a seam scope or the Wilkens Anderson seam projector. Eitherofthese are informative but not all inclusive as they show only the small area cut for inspection.
The frequency of inspection will vary depending on each company’s standards; however, a complete tear down inspection should be made on one can from each seaming station a minimum of every four hours or major fraction thereof, preferably as soon as the machine warms up after start up following a shut down. A complete check of a can from each seaming station should be made immediately following a major jam.
When defects are found from any particular seaming station a second check should be made before making adjustments. When making a seam check you find a major visual defect in a can, this should be taken care of immediately before the rest of the cans are checked. On high speed lines several hundreds or thousands of bad seams could be run before corrective measures are taken if you wait until completion of inspection. It is very important to register all measurements taken for the benefit of the following shift, permanent record and preventa-tive maintenance.
To get a full and complete check the seam can be stripped or torn down. Use the sketches, photos and steps on the next few pages.
1.) Remove the cover panel with a suitable can opener, preferably the bacteriological type as supplied by Wilkens – Anderson Co. Before discarding this panel inspect it closely for proper coding if using a die or type marker system.
Most aluminum can panels can be removed with the End Cutters relatively fast and clean in preparation for the next step on the next page.
2.) With a pair of end cutters (nippers) tear out the remaining portion of the cover panel using a motion of direction away from the center of the can so the metal will tear cleanly over the top of the body hook.
3.) Use the nippers to make a vertical cut through both cover hook and can body.
4.) Use the flat side of the nippers to gently tap the cover hook downward so that it disengages from the body hook around the full periphery of the can. If the remaining cover panel was stripped out correctly there shouldn’t be any fold over on the cover hook portion making it difficult to separate these factions. Do Not use heavy blows or force separation of the can components or end results will be distorted.
5.) Keep the cover hook portion of the seam in its natural shape when removed from the can body to insure the most representative evaluation of the wrinkle. If the cover hook is straightened out it will also straighten out the wrinkle indicating a better seam than is actually obtained.
6.) Measure the Body Hook. Body Hook and Cover Hook should be measured at four or five separate locations to obtain the minimum and maximum dimensions for comparisons.