So you've got your latest sensational seasonal in the tank. With summer approaching, you want this one going into cans. You're set on something perfectly portable for the beach, a hike, or sipping around the campfire. You've got your digitally printed shrink sleeves in production with your kickass label partners at Summit, but now you're wondering. How exactly do those shrink sleeves get onto the cans?
Let's take a look at the three most common shrink sleeve application methods and why they work best for the industries they serve. If you're still at stage one: 'What are shrink sleeves?', can we recommend heading here instead? Fair warning, we're going to get a bit technical with this one, so you're going to want a coffee on hand.
How is My Shrink Printed?
The printer (that's the 'us' in this equation) busts out your artwork on a digital (or flexo) press. The text goes inside the shrink sleeve, and then it's seamed, so it looks like a big long tube or a 'sleeve.' Hence the name, shrink sleeve! Next, it makes its merry way to the applicator.
How Does the Sleeve Shrink?
Now, this is a 'hot' question that we get a lot! After the sleeve is applied to the container, it's run through a heat tunnel. Here evenly dispensed heat manipulates the sleeve, so it shrinks and conforms to the container it's being applied to.
The three most common heat tunnels are hot air, radiant, and steam; some tunnels use two heat sources in conjunction! Each of these has its own advantages and disadvantages, but that's content for another day.
Applying Shrink Sleeves with Vertical/Mandrel Systems
Since we got this blog started talking about shrink sleeves on cans, let's take a look at the most common application system for those aluminum all-stars. A vertical/mandrel system is often chosen for:
- high volume runs,
- continuous 24/7 operation
- applying shrink sleeves to round or cylindrical containers.
Cylinder-like tube suspended within a drive roller system (the mandrel), this system opens the sleeve as it moves downwards. The sleeve is then cut to fall (or be driven) directly onto the moving container.
Generally, this operates at intermediate to high speeds and requires careful attention to specifications. Specs like the lay-flat (width of the seamed sleeve) and the Coefficient of Friction (CoF) ensure that the application is consistent. Oof right? In simple terms, operators are making sure the friction and sleeve size are working in perfect harmony.
A mandrel application system is pretty sophisticated, but it's also adaptable to various can sizes. If you have more questions on this type of application system, our friends at Vessel Packaging would be happy to help you out!
Applying Shrink Sleeves with Carousel/Rotary Systems
Shrink sleeves are incredibly versatile and are showing up on containers of all shapes, sizes and materials. So, the application systems have to be built to be just as flexible as the sleeves they're applying. One of these systems is the carousel/rotary application.
- Best for low to intermediate speeds
- Carousel design helps stabilize non-round or uniquely shaped containers
- Tolerates a wider variety of materials
- Well suited to frequent material changes
All of this flexibility makes the carousel system the Swiss Army Knife of shrink sleeve application.
Applying Shrink Sleeves with Direct Apply Systems
Fun fact for your next cocktail party: shrink sleeves were initially invented in Japan in the 1960s as a means of providing tamper evidence for sake bottles. A small shrink sleeve would be applied to a bottle's neck to seal the product; if it was opened or removed, it indicated that the product had been tampered with. Nerd alert, right?
Tamper bands are still in use today across a variety of industries, including sports nutrition and nutraceuticals! More often than not, they are applied to containers using a direct-apply system.
These systems are small but mighty. They use a targeted application mechanism to place a tamper band shrink sleeve directly to the area it needs to be shrunk on.
- Operate at low to intermediate speeds
- Ensures the sleeve is applied to the correct portion of the container
- Shrinks each and every time consistently
While we know what we do best (that's printing labels and shrink sleeves), we also love exploring the supply chains we are a part of. When we call ourselves label nerds, we really, really mean it.
So we hope this insider look at how shrink sleeves are applied has answered any questions you might have and given you as much joy as we had in writing it. If not (which seems likely), let's chat. We'll put you in touch with our expert partners, so you don't ever have to think about this stuff again.