ROPP Caps for Bottles

Engineering
1

Hi
Usually, Aluminum ROPP caps for bottles have seven bridges.
Is the number ‘seven’ sacrosanct?
Does the umber have to be an odd number? Why?
Can we have just four bridges?
Would that pose any problem on bottle-cap sealing machine?

Thank you
K D Thakkar

2

Having seven bridges in aluminum ROPP caps is not a strict rule, it’s just a common design. Seven bridges give good strength and make it easy to see when the cap has been opened. Using an odd number like seven also helps the bridges break more evenly.

Some caps are made with four bridges, and that also works. But with fewer bridges, the break may not look as neat, and the band may be a bit weaker, which could make it easier to tamper with.

When it comes to the machines that seal these caps, using four bridges instead of seven usually doesn’t cause big problems. The machine may just need a few small adjustments so the cap seals tightly and breaks properly when opened.

1 Like
3

Thank you for your response.
Are you from a ROPP cap manufacturing company?
What kind of ‘small adjustments’ will the sealing machine need.
In fact, we tried caps with four bridges and shop-floor reported breaking of one or two bridges. This didn’t sound logical, hence this question in the group.
Thanks once again

4

I am currently employed as a Senior Manager at my organization, where I lead quality assurance operations. Alongside this role, I also provide consultancy services, leveraging my expertise to help others to optimize their QA processes, resolve complex quality issues, and enhance regulatory compliance.

seven bridges are very close together, but four bridges are spaced far apart. When bridges are far apart, each one has to carry more pressure, which can cause them to break more easily. To fix this, we can slow down the speed / move the knives to better positions, and adjust the pressure of the rollers.

5

Doesn’t anyone else have something to share on this topic?
Do we have engineers in the group?
Anyone from ROPP Cap-vendor side?
Anyone having faced problem of cap opening, especially with 22 mm caps and very small bottles (5 ml - 10 ml)?
Please respond. Thank you

6

Torque Application, Validation & Capping Machine Setup is always based on number of bridge and its performance for band integrity until first opening. It’s recommendable to use seven bridge ROPP cap for good integrity provider bridge which is seven. Distance is more for four bridges so it not at all proposed good integrity product, however based on product’s pack strength, tamper- evidence and machinability requirement.

7

According to my experience as a QA /QC person who has worked in several pharmaceutical manufacturing companies, the observations are as follows,

  • The quality of bridges of ROPP caps decides their proper functioning. The thinner the bridges, the more easily they cut / break while ROPP caps are being sealed on the bottles on packaging lines. The thicker the bridges, the harder it is to break open the bridges even with great pressure applied by the patient while opening the bottle by unscrewing for the first time. Therefore, optimum bridge thickness is required to ensure that the bridges can be easily cut / broken while opening the bottle cap for the first time by the patient.
  • Secondly, the optimum pressure is required to be applied when bottles are sealed with ROPP caps. If the pressure applied is too low, then there is no proper “thread formation” to the caps when doing a sealing operation, and the cap gets loosely fitted on the mouth of the bottle, thereby it just keeps rolling over the neck without threads and can cause leakage of the liquid filled in the bottle.
  • When higher pressure is applied during the bottle sealing operation, the cap gets cut at the threads or it does not easily open while unscrewing.
  • Therefore, optimum pressure should be applied while sealing the bottles with ROPP caps.
    -These parameters should be set during process optimization studies and must be confirmed in process validation studies. The number of bridges to cap depends upon the size (diameter) of the ROPP cap. Four numbers are very few for bridges.
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