At Silgan Closures, we go above and beyond to ensure we’re delivering a consistent and high-performing product. For steel closures, we perform different checks to ensure the closure is applied and will perform properly: Pull-up, Removal Torque, and Security.
Before you get started, you’ll need:
- A thin felt-tip marker (the thinner the better!)
- A ruler
- Removal torque meter
1. How to Perform a Pull-up Check
Step 1: Locate the mold parting line on the finish and place a mark on that line
Step 2: To the right of the mold parting line, mark the leading edge of the lug
Step 3: Measure and record the distance between the two marks
What the data means and why it matters:
A pull-up is a non-destructive method for measuring engagement between the lugs and the finish. The pull-up is the distance between the leading edge of the cap lug and the neck finish mold parting line.
This method is measured in 1/16” increments. The distance should be 4/16”, plus or minus 2/16”. If your measurement is below 2/16”, or reaches a negative number, it’s an indication that the closure was over applied and potentially stripped. The cause may be that too much top load pressure and/or too much application torque was used.
If your pull-up measurement is significantly above 6/16”, the engagement may not be tight enough, which may affect the final seal. However, this distance can vary in either direction due to dimensional characteristics of the glass finish and or closures.
Pro Tips
- Check pull-up distance after making machine adjustments
- Avoid running with extreme pull-ranges of either (0 to +1) or (+9 to +10)
- Always check closure security after any significant change in pull-up values
- Perform this check at the capper and after the cooling process
- Perform in 15- to 30-minute intervals
2. How to Perform Removal Torque Check
Step 1: Place the container securely into a removal torque meter ensuring that there is no potential for the container to slip
Step 2: With a continuous, even motion rotate the closure in a smooth, counter-clockwise motion without a rapid, slow or inconsistent manner.
Step 3: Record the measurement
What the data means and why it matters:
This is an optional check that may be performed for Quality Control records, but it is not recommended to be used as a control for closure application. Removal torques vary significantly with glass lubricant or treatment, filling conditions, sealing conditions, package vacuum level and how tightly the closure is applied. Torque reading differences under identical conditions can also be noted between personnel operating the torque meter. For this reason, we have not prescribed any specific torque limits.
A general rule, to be used only as a guideline, is that the minimum removal torque at the time of capping should be 1/6 the millimeter closure size in inch-pounds at the minimum security level.
3. How to Perform a Security Check
Step 1: Place a vertical mark from along the side of the closure and extend the line to the jar finish. As the container needs to be opened at this point, it would be best to take a removal torque reading but is not required (see Removal Torque Check)
Step 2: Once the container is opened reapply the closure to the point at which resistance is met easily with minimal force, at times referred to as “Finger Tight”
Step 3: Measure and record the distance between the lines
What the data means and why it matters:
A security check is a destructive method that measures lug tension of an applied closure. This method is measured in 1/16” increments. What you’re looking for is similar to that of a pull-up check but different in the sense that you’re measuring the lug tension rather than the closure’s engagement with the jar.
The distance should be 5/16”, plus or minus 2/16”. If the number goes significantly below 3/16” or above 7/16”, too much or too little lug tension is occurring. Too little tension may affect the final seal while too much may affect the long-term performance of the closure.
Pro Tips
- The mold parting line for the body of the jar may not be aligned with that of the finish. Take care in marking the correct line.
- For more accurate results, stop re-applying the closure at the moment you feel the resistance from the lug interacting with the jar
About Silgan U
Silgan University (aka Silgan U) is an in-person event for Silgan customers. It provides an opportunity to learn the basics of food and beverage closure design and manufacturing. Customers who attend will walk away with the knowledge and tools they need to feel confident in their next closure project. To learn more, contact A.J. Miller at A.J.Miller@silganclosures.com
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