Two suppliers can send you a correct bottle and a correct cap, and the pack still leaks. Torque is where that happens, because it belongs to neither supplier and gets set on your line.
The 3 Numbers Your Line Runs On
| Number | Where it comes from | What it tells you |
|---|---|---|
| Application torque | Set on your capping head and measured at the filler. | How hard the liner is pressed onto your sealing surface. |
| Removal torque, fresh | Measured minutes after capping. | Whether the closure seated properly on your line right now. |
| Removal torque, aged | Measured on samples held for a day or more. | What your customer meets when they open the pack. |
Why Aged Removal Torque Is the Honest Figure
A liner does not finish compressing when the capping head lets go. It keeps creeping for hours, and a plastic closure relaxes around it, so the force needed to open your pack keeps falling.
Testing straight off the filler therefore reads high and hides a weak seal. Hold samples, then measure, and set your window on that figure rather than on the fresh one.
What Moves Your Torque Window
Four things change it. Closure material and thread profile, since a stiff cap transmits force differently from a flexible one. Liner thickness and hardness, which decide how far the cap turns before the seal closes.
Then the glass finish itself, whose height and thread tolerance sit on the drawing. And your line speed, because a faster head applies force over a shorter time. SGSBOTTLE issues the finish drawing with every quotation, for glass from 14 lines in Shandong and Xuzhou, so your closure supplier can set the window against real dimensions.
Thread and sealing-surface tolerances come off the SGSBOTTLE drawing for all 14 lines.
How the Test Is Run
A torque tester grips the bottle body and reads the peak force as the cap turns. Take a sample set across the run rather than one bottle, because cavity-to-cavity variation shows up here before it shows up anywhere else.
Record application torque, fresh removal and aged removal for each sample. A spread that widens across cavities points at the glass finish; a spread that widens over time points at the liner.
Setting a Window You Can Defend
Give yourself a band, not a target. A single number cannot survive normal variation in liner thickness, closure moulding and finish tolerance, and a line chasing one figure will drift outside it constantly.
Write the band into your specification alongside the fill and the liner it was tested with. A 750 ml (25 oz) bottle re-sourced later can then be matched against a real requirement instead of a memory.
What Goes on Your Enquiry
Your closure and liner, the format in ml and oz, your capping head and line speed, and the fill. SGSBOTTLE comes back with the finish drawing, the tolerances behind it and a torque window tested on your own closure.