Shrink sleeve packaging is on the rise, primarily in the beverage industry, though it has also seen an increase in use in tamper-resistant packaging applications.
Shrink sleeves are gaining in popularity in these applications because they provide marketing optimization by allowing the product manufacturer to utilize the entire surface of the package for artwork and information, regardless of surface contours.
This type of packaging enables rapid, cost-effective packaging design changes, providing product marketing groups the ability to make sure that the product stands out from competitive products on the shelf.
As with all packaging applications, finding ways to increase efficiency is critical in shrink sleeve packaging operations, as increased efficiency directly translates into higher throughput and greater profit margins.
Process and challenges
Shrink sleeve film is generally composed of either polyvinyl chloride or polyethylene terephthalate glycol-modified.
The film is converted from a flat film to a tube structure with an overlap seal.
During the labeling process, the tube is cut to length by the labeling equipment and placed over the exterior of the package.
The package then proceeds through a heat tunnel, generating radiant heat, hot air, steam, or hybrid of these, where the film shrinks under the heat exposure to conform to the shape of the package.
As with all packaging film, shrink sleeve film must be spliced together, joining the end of an expiring roll of film to the start of a new one.
The typical challenge to creating a hand splice in these applications is the struggle to achieve a consistent splice joint for smooth operation over the mandrel.
In many cases, an overlap joint is created with the expiring tube of material being ‘tucked’ inside the new tube, thus allowing the new material to be guided over the mandrel.
This can create issues if the combination of the tape and double-thickness of shrink sleeve does not move smoothly over the forming mandrel, as is frequently the case.
The process of expanding the shrink sleeve to a tube shape through the use of a mandrel within the labeling machine requires the material to be very consistent through the splice joint.
Any inconsistencies in the film alignment, print pattern repeat, and/or ability to open to a tube shape can result in a stoppage of the labeler and significant downtime.
In addition, it can be difficult and time-consuming for an operator to create a manual splice in-registration, such that the repeat pattern of the printed material remains consistent through the splice joint.
Finally, creating a manual splice generally requires the process to be stopped as the expiring roll is spliced into the new roll.
The urgency to minimize production downtime is difficult for the operator to balance with the effort required to create a very precise splice joint that does not exhibit any of the potential problem areas noted above, thus leading to stress and errors.
Maximizing efficiency
Automatic splicing technology is key to overcoming splicing challenges in shrink sleeve packaging.
The technology in the form of the patent pending Butler Automatic SP3HSL Sleeve Splicer for example solves the challenge of striking this balance faced in manual splicing.
The SP3HSL provides a zero-speed, in-registration, automatic splice from an expiring roll of film to a new roll, all while continuously providing film to the downstream process without interruption or any need to reduce the process speed.
It provides a butt-splice joint with tape on both sides and can support line speeds up to 450 feet per minute.
To achieve this, the operator loads a new roll of sleeve material on the air shaft of the splicer and prepares the splice.
This process usually takes two to three minutes and is performed while the downstream process is supplied material from the initial roll, thus eliminating the need for line stoppage.
Then, when a preset, calculated diameter of the running roll has been reached, the splicer automatically splices the expiring roll to the prepared splice joint without any need for operator involvement.
The splicer will create an in-registration, two-sided tape joint that is both strong and capable of fitting over the forming mandrel.
The overall product thickness is kept to a minimum with automatic splicing by forming a butt-splice joint, thereby eliminating the extra thickness of sleeve material that results from the typical ‘tuck’ joint.
In addition, the SP3HSL incorporates patent pending guiding features to ensure the sleeve is centered going through the splice head, regardless of its lateral position exiting the roll.
This ensures the properly prepared splice will be in alignment with the expiring roll of material and all resulting packages will be sleeved correctly.
Finally, the SP3HSL uses a fiber-optic, multi-color sensor to address the challenge of identifying the registration marks, printed image gaps, or printed image repeat patterns in the film artwork.
The combination of this sensing hardware and the ability to offset the splice from the mark via the splicer software provides operators with the ability to locate the splice joint precisely and repeatedly anywhere on the product.
Automatic splicing in shrink sleeve packaging
A typical sleeve machine processes between 200 and 800 bottles each minute.
Assuming an average label length of six inches, the process could consume 400 feet of sleeve material per minute.
At that rate, the typical roll of sleeve film lasts less than 15 minutes before it expires and must be spliced to a new roll.
In these applications, it is not unusual for roll changes and manual splicing to take at least two to three minutes each time, often longer.
By eliminating this eight to 12 minutes or more of downtime per hour, automatic splicing can result in an immediate 13-20% increase in production.
In conclusion, automatic splicing is a critically important tool to maximize efficiency in increasingly popular shrink sleeve packaging applications.
Automatic splicing technology enables packaging operations to fully reap the benefits of this type of packaging, in terms of marketing optimization and rapid, cost-effective packaging design changes.
Story by Michael Mucci, VP of Engineering, Butler Automatic
