Closure Application Torque

The application torque of closures must be controlled in order for the closures to perform properly in the field. Closures must be applied tight enough to maintain a seal and to resist closure back-off, but must not be applied so tightly that the end user cannot remove the closure.

A general guide is that the application torque in inches per pound should equal approximately half of the closure millimeter size. As application torque cannot be measured directly on an automatic capper, removal torque measurements are used as an indication of application torque. Since each package will have its own relationship of application to removal torque, the packager should determine this relationship for each of his packages. By applying caps by hand with a torque meter and immediately measuring the removal torque, a correlation between application and removal torque can be determined. This correlation can then be used as an indicator of the actual application torque generated by the capper. By checking removal torque regularly after capping, one can determine if there is a need for adjustment.

Cap SizeTorque (Inches/Pound)
  Glass Plastic
15 6-9 lbs. 7-9 lbs.
20 8-12 10-12
24 10-15 12-15
28 11-17 13-17
33 13-20 16-20
38 15-23 19-23
43 17-26 21-26
45 18-28 23-28
48 19-29 24-29
53 21-32 27-32
58 23-35 29-35
63 25-38 31-38
70 28-42 35-42
83 34-49 41-59
89 36-53 44-53
100 40-60 48-60
110 45-65 55-65
120 48-72 60-72