Ultrasonic fobbing systems

Why the ultrasonic fobbing systems ?

Common disadvantages of the closure optic inspection systems: 

  • Optic, with 1, 2, or 3 CCD-cameras
  • Tamper evidence band 
  • Missing closure, inclined and high closure

based on CCD and CMOS-cameras, are high price and complexity.   More, they all require dry closures, as pre-condition for the optic closure inspection. The disadvantage of the closure inspection based on single analog photosensor, is that it only detects missing closures, when this type of closure defect is typically < 20 % of all of the closure defects, the remaining 80 % being:   

  • broken TE band;  
  • closure too high or inclined.  

Then, in the reality, a cheap optic closure inspection with analog photosensor shall be a guarantee to send to the Market 80 % of the leaking closures.

Ultrasonic fobbing inspection was born for multi lane conveyors like this. It can also be applied to single-lanes in the filler outfeed, if the conveyor is tilted around 10º, to guarantee the same full contact with the left side guide and ultrasound transducer (image credit Stratec® Bbull®)

A different approach to safety

In the reality, it exists a completely different way to attack the food safety problem lying back of the closure inspection. What they really look for all these inspections ? …open closures.   Open enough to let air come in and/or product get out, when the bottle is squeezed and tilted upside-down.   This last being the condition when also a microscopic opening reveals itself.    If a bottle treated that way doesn’t loose product, it means it is sealed. The “way-out” we’ll describe in the following is nothing prototypical, it exists since several years. Unfortunately, only a few Vendors keeps it into their catalogue.  Keep it, … and rarely propose to Bottlers !     We all know that shaking a PET or glass container filled with a carbonated product, results in a fast increase on internal pressure, showing macroscopic effects of sprinkling out, if the container is not perfectly sealed.   

A different way to shake the liquid is exposing it to a powerful beam of ultrasounds: mechanical energy is then transferred to the carbonated product and, if the entire bottle (not only its closure) is not truly sealed, the liquid shall (spectacularly) sprinkle out.  A following underfilling level inspection, the same we’d however have had out of a filling bloc, shall shortly later reject this bottles because macroscopically underfilled.  It’s an extremely simple and cheap solution, not requiring optoelectronics know-how to maintenance staff, virtually immune by the losses-on-production (false rejects) which frequently accompain all the other kinds of leakage inspection.    On the opposite:

  • periodic maintenance limited to cleaning of the ultrasound transducer and conveyor;
  • electronic installation limited to connection to 230 VAC mains.

Figure before shows its action after the filling bloc, as an inclined oscillating metal rail which align all bottles the same distance, equalizing this way the transfer of mechanical energy to the liquid. Maximum production speed is limited to 40 000 bph.   Liquid has to be carbonated.  When carbonation is minimum, it has to be a sugar-added drink.

Links to other pages about Closure Inspection:

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