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Third Edition, Nov 2016
ACS V4.2
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38
Section E. Seam Measurement
E.2
Manual Seam Evaluation Process
Full can seam tear down should be done prior to production every day. Can seam height and width should be checked
frequently (once every three to five minutes) throughout production. Production should be stopped if there is a change
of more than 2/1000 on either dimension.
A full seam tear down should be performed to determine the cause of the change and the adjustments required. The
procedure for checking the quality of your seams is called a “Can Seam Tear Down”. This enables you to make various
measurements as outlined in this Section E.
E.3
Reading a Seam Micrometer
Before commencing a Can Seam Tear Down, you will need to be conversant in reading a seam micrometer.
Reading a micrometer of any kind is not as hard as some may think. If you can simply add and subtract, you can read a
Micrometer. Below are a few simple pointers to get you started.
Each “Tick” Thimble Sleeve is equal to 0.025” (25 Thousandths’ of an inch) therefore 0.025” x 4 Ticks = 0.100” and
so on.
Each “Tick” on the Thimble is equal to 0.001” (1 Thousandth of an inch) therefore on complete revolution from 0
back to 0 is equal to 0.025”.
Example #1
Looking at the photo below (Figure 33) note the Micrometer reads a total of 19 visible “Ticks” on the inside shaft. 19 x
0.025 = 0.475”. To make it simpler for the reader of the Micrometer the “Ticks” at every 0.100” are labelled in sequence
1-2-3-4-5-6 … (1=0.100”, 2=0.200” so on). Figure 33 displays “4” = 0.400”+ 3 ”Ticks” = 0.075” to total 0.475”.
Figure 33 Seam Micrometer 0 – 1“, Example #1
Example #2
The following example (Figure 34) reads 10 “Ticks” each “Tick on the Thimble Sleeve is worth 0.025” therefore the
Micrometer reads 0.250”. Simply explained “2” = 0.200” + 2 “Ticks” (0.025”) = 0.050” for a Total of 0.250”.
