Thickness
| Seam thickness is measured perpendicular to the layers of
metal in the seam. A double seam is comprised of two layers of body hook and three layers
from the cover hook, resulting inFive overlapping layers as can be seen in the figure
above. Seam thickness can be an indicator of how tight a seam is. (If a seam is loose the
thickness will be larger.) |
| Procedure: Step 1- Measure the thickness using a can seam micrometer. The micrometer is placed on the top of the double seam so that the seam lies between the anvil and the spindle screw. Hold the micrometer level by balancing it with an index finger. Do not hold the tip of the micrometer. The anvil will not be able to adjust to the inside seam wall and will cause false readings. |
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Step 2- Turn the thimble clockwise until it is snug. Be careful not to overly tighten as this will compress the seam and give a smaller reading. The thickness is measured twice: first 90° to the left of the side seam, and then 90° to the right of the side seam. Record the results on the worksheet. More measurements should be recorded if the first two measurements are out of the normal range. |
| Note: The micrometer is read in .001"units. The rotating spindle has 25 units marked. One revolution equals 0.025", and two revolutions equal 0.050". The thickness for any size can should never exceed 0.053" |  |