In July 2019, the EU commission published the Plastic Strategy paper to reduce plastic waste, including a regulation with regard to closures on plastic beverage bottles: Plastic closures must remain attached to the bottles from July 2024 at the latest. This poses major challenges for the industry. Several cap solutions have already appeared in the market. As a logical consequence, PETplanet Insider is therefore asking about the inspection options for these closures. Find out here about the inspection solutions for tethered caps from: IMD, Intravis, Pressco and Sacmi.
Sacmi Imola, Mr Stefano Severi, Sales Specialist Manager, Rigid Packaging Technologies BU
PETplanet: Has your company already developed inspection systems for tethered caps? If so, what were the challenges during development and what are the new inspection parameters?
This subject actually covers two different situations: tethered caps with the cut made inside the mould and those on which the cut is made externally with a scoring machine such as a Sacmi SFM. If the cut is made inside the mould, it is large enough to be inspected with standard CVS systems. Sacmi has, for many years, been designing vision systems for the inspection of complex caps such as sport or hinge caps. Our globally renowned CVS360-3D applies 3D algorithms that can accurately ‘unroll’ the sidewall of a cap, whatever its shape, to create a 2D image, dynamically compensating for any deformation that may stem from the object’s spatial position, perspective or lens deformation.
This builds a perfect image on which we can apply all our inspection algorithms. Already successfully applied in hundreds of applications, this technique has also been used in the inspection of tethered caps. If, instead, the cut is made externally with a scoring machine (e.g. an SFM), it is very thin (a few hundredths of a mm) and is very difficult to inspect with conventional vision systems. For this type of application, Sacmi recently presented a new machine called PFMC (Pull Force Measuring-CVS machine) which performs a mechanical breakage test of the tamper-evident band. This machine periodically takes a number of caps from production and performs mechanical breakage tests. It also incorporates a CVS system (called CVS-CUT); the latter is configured with an ultra-high-resolution camera that unrolls the cap sidewall and ensures the cut is controlled to perfection.
Among the numerous checks performed by CVS-CUT, the most interesting for cap manufacturers are: cut quality (thickness and straightness), measurement of the bridge section, marks on the knurls, misaligned cut joint, etc. Of course, PFMC is also suitable for inspecting tethered caps with tamper-evident bands produced in the mould, providing additional information on the breaking force related to each single cavity and more precise inspection of cuts and bridges.
PETplanet: Can all tethered cap designs be inspected with just one inspection system?
Yes, the flexibility of our Sacmi Computer Vision Software easily lets users create dedicated inspection recipes for different cap types.
PETplanet: What must users be prepared for? Are the new systems easy to integrate into existing processes? What levels of technical effort and financial expenditure are involved?
As mentioned above, the approach to tethered cap inspection differs depending on the type of cut (in-mould or external). Sacmi can provide simple vision systems (CVS – Cap Vision Systems), inspection solutions that integrate vision and handling (CHS machines), or dedicated machines specifically designed to test the pull force needed to break the tamper-evident band (PFMC machine). CVS and CHS can be configured or expanded according to customer requirements.
While CHS machines are usually delivered with the CVS360-3D module pre-installed, which makes them ready for the inspection of tethered caps, standard CVS models are usually configured as per the customer’s requirements, so it may be necessary to add the CVS360-3D module: this requires only a small investment and some additional space in the conveyor. Both solutions (CVS and CHS) feature the same software platform (our well-known Sacmi Computer Vision Software), so operators do not have to learn something completely new, they just have to learn how to use the CVS360-3D. Moreover, a Wizard greatly simplifies this operation, which can be completed in just a few steps. The PFMC machine, instead, incorporates a CVS-CUT Vision System. This means that workers who already know how to use the Sacmi CVS can immediately operate this new machine too; in addition, untrained workers can learn easily via the software platform’s user-friendly HMI.