The craft beer revolution has taken the world by storm, but as craft breweries multiply and gain more market share, new challenges arise. Here’s one: seaming cans reliably and consistently.
Modern cans have remained largely unchanged for more than a century, with their origins dating all the way back in the 19th century, and this has remained one of the most popular means to store and transport food and beverages ever since.
Why cans? Why aluminum?
The freshness factor is the biggest benefit of aluminum. Cans protect their contents against light and oxygen and can keep the beer tasting as fresh at the customers’ home as it does at the brewery.
A second factor is efficiency. Aluminum cans are lightweight and stackable. This makes transportation easier, less expensive and friendlier to the environment.
Finally, aluminum cans are sustainable. Recycling aluminum cans is amazingly easy and fast, recycled aluminum can turn into a new can in a matter of 60 days or less. The average can today usually contains as much as 70 percent recycled aluminum.
How do you can beer?
At its core, a beer can is made up of two parts: the end (or lid) and body. Can makers supply both cans and ends. In terms of size, the typical 12-ounce can is typically a “200/211” (2-inch diameter lid on a 2 and 11/16-inch body).
When you purchase the can body, you will notice it has a flange. The end contains a curl. When the filled can reaches the seamer, it is raised up by the seamer and the end is placed on top of the can by a tooling known as the “chuck.” The chuck holds the end in place, right on top of the filled can, while the seamer does its magic. The seaming works by folding up the edge of the can (the flange) with the curl of the end. This process of “folding” is called double seaming — and is done in two stages by the seamer.
In the first operation, a tooling part called the “first operation roll” comes in and folds the curl into the flange. The two are now held in place but are “loose,” so a “second operation roll” comes in and irons out the seam to make sure that it is nice and tight.
Unfortunately, this process isn’t enough to protect the beer from contaminants or from leaking out. This is where the compound comes in. This rubbery substance is sprayed onto the insides of the end by the manufacturer and makes sure that the double seam is sealed tightly.
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Seamers, seamers, seamers
The craft beer revolution brought about a few changes to a fairly traditional market. A handful of seamer manufacturers, the bigger ones located in the United States, Switzerland, Italy and China, spearheaded the industry. They are complemented by only a slightly larger rebuilder market, where old broken down seamers were taken apart and rebuilt to create a thriving preowned market that was substantially cheaper than the original manufacturer price.
There are several types of seamers, starting with one head and going all the way up to 24 heads. Each head multiplies the number of cans that the seamer is capable of seaming per minute. Theoretically, an 18-headed seamer rotating at the same speed as a one-headed seamer would close cans 18 times faster. Each seamer head can be considered a separate machine running in parallel to the other heads. One headed and manual seamers are pretty slow to close a can, while the big beverage companies often run their seaming lines at rates of 1,200, 1,800 and up to as much as 2,400 cans per minute (CPM).
When craft brewers started to can, they looked for different solutions. This gave way to a new category of smaller seamer manufacturers. These focus on inexpensive, simpler, easier to maintain machine designs, running at slower rates with a small number of heads (usually between one and four).
Cans sound great, so what’s the catch?
Well, there’s always a catch. When you think of craft beer, you ultimately think about quality. This means that the unique, great tasting beer people like to drink at the brewery needs to last through containment, storage, transportation, distribution all the way to wherever the customer decides to drink it. So the question remains — how to make sure that the customer opening the can a few weeks after production experiences the exact same taste?
There are lots of parts that need to fit together for the can to be a truly sealed container. Most of these are the responsibility of the can maker. They make sure that the cans and ends are properly made (there are many different parameters that ensure that is the case) and that the “easy open” tab doesn’t break off when you pop the top.
However, there are some things that the can-makers can’t do for the breweries, the most important of which is the seaming process. This is done at the brewery, which means it’s the brewery’s responsibility to make sure it’s done right, and this is no easy feat.
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How do I check the can seams? (Read on…)
How do I check the can seams?
The first step is to recognize that you need a quality control lab, and no, your taste buds don’t count. You need to extend your testing to include the can as well and to make sure that it is properly sealed and won’t leak or be exposed to outside contaminants. Even microorganisms can get into the can and contaminate the beer if the seam isn’t formed correctly.
Once upon a time, testing the seams involved a tiny micrometer. This is a small hand-held device that can check small measurements such as the seam thickness and seam height, the two external measurements of the double seam.
However, aluminum is a tricky material. It’s soft and flexible, ironically the very properties that make it such a great container would make these manual measurements essentially worthless. The value of a measurement taken with a micrometer mostly depends on the person holding it. How much force are they using? What angle are they holding the micrometer at? One person can end up with one set of results, while another will show completely different measurement values.
Obviously, an objective, hands-free gauge is needed here to make sure that the cans are sealed shut.
That gauge is a computerized double-seam gauge, or seam inspection. The operator pulls can samples off the line periodically, empties them, dries them out and then performs a destructive seam measurement on each of the sample cans. This involves cutting the cans with a seam saw to expose the cross section of the double seam. Then the operator measures the cut cans one at a time with a SEAMetal or similar double seam inspection system.
The SEAMetal software then does most of the work by measuring the important values instantly and automatically. The seam standards are provided by the can suppliers, and as long as the values are within the specifications, the cans are sealed tight. There are a few critical values that need to be tested with the system.
Seamer setup
If the can samples tested with the SEAMetal are within specifications, all is well and production can continue as usual. But what happens if the values are out of specs?
This will inevitably happen as temperatures change, the machinery loosens up and parts begin to wear. This is the brewer’s first warning that something in production has gone wrong long before we see a leak or contamination. That’s when you need to go back to the source, or in this case – the seamer. There are usually only a couple of reasons why a seamer isn’t producing good seams:
- A tooling (chuck, roll, bearing, etc.) may be damaged
- The chuck/roll distance isn’t set up right
The traditional way to find and correct seamer issue is to use feeler gauges or, in some cases, wire gauges. The operator spaces the roll/chuck distance with the feeler gauges, runs cans, stops production, tests the cans and repeats this process until the seamer is adjusted correctly.
The problem with feeler gauges is that they require years of experience to use correctly, they’re time-consuming and an operator basically guesses their way to seamer set up. Their thicknesses also tends to change over time and repeated use.
The modern approach is to use a clearance gauge, which is a computerized visual gauge that is placed inside the seamer like a can and allows the operator to see the position of the roll in all directions. This completely takes the guesswork out of the process because the roll position can be adjusted while looking at a live image. This means that the seamer is adjusted once, quickly and accurately before continuing with production.
Routine usage of a seam inspection system (SEAMetal) and a seamer setup gauge (clearance gauge) has been proven to find trends of a problem before it becomes a serious complication. A short delay in production can be annoying, but a recall can be devastating. Finding and correcting problems at the brewery is a lot easier and definitely more cost effective than discovering them out in the field. After all, no one wants their customer exposed to a less than perfect product. In today’s environment of Yelp and social media, everyone is literally a critic with a huge audience.
Canning does not have to be a huge headache. It is somewhat of an investment, but a good partnership with a can supplier, a good filler and seamer, some quality control equipment and the correct mindset and your beer will be flowing fresh from those cans in no time.
Ofer LaOr is the chief technical offier for Quality By Vision, a leading quality control manufacturer for the canning and filling industry. Quality By Vision has also created a free resource for craft breweries who want to understand more about canning. Visit it here!
