Can Sealing Guide: Choosing the Right Can Sealing Machine - Levapack

A Complete Guide of Can Sealing: How to Choose the Right Can Sealing Machine

Humans started experimenting with the storage of food once they got tired of having to hunt and forage every day. It started to make more sense to make the most of a good hunt by storing whatever is left for a rainy day. It may have been rudimentary back in the day, but this formed the basis for all the storage techniques people are enjoying today, be it for food or any other item. One of the most prominent storage methods in heavy use today is canning.

We are going to look at what canning is, how sealing is done, the benefits it brings to the table, and how you can choose the right can sealing machine for your manufacturing plant. If you have been looking to get into the can sealing business, then this is exactly what you need to be reading right now.

Table of Contents

What is a Can Seaming Machine?

Can Sealing Machine

The demand for safe and durable packaging is what led to canning being invented in the first place, and over the years, the technology behind it has grown immensely. As the need for more reliable canning techniques increased, the machines used to seam these cans also improved.

A seaming machine for cans is a special mechanical contraption that is used to seal the lid of the can body after sealing in the items that need to be stored. Can seams are usually made of aluminum or steel and once the seaming is done, the items inside continue to remain in a fresh state until the day someone opens it or when the expiration date has passed.

Can seaming machines come in varying sizes and types, depending on the scope of the work. The bottom line, however, is that they all work in the same way. This is the reason why they are used in a vast number of industries, from food and beverage, the automotive industry, among many others.

Parts of a Can Seaming Machine

Operational Machine

A can seamer depends on various components for it to handle its work properly. Each of these components serves a specific function. Without each, the entire machine will be reduced to a dud. The following are the main parts of a can seaming machine.

Seamer Head: Also called the Chuck, this is the part that holds the can together as the process of double seaming is being conducted. It also offers the can protection against the pressure of the seaming rollers, which can be heavy at times and can leave dents if left unchecked. The dimension of a can seamer depends on the diameter of the can being sealed. This means that the seamer head has to be switched out every time the size of the cans changes.

Seaming Rollers: Every can seaming machine comes equipped with two seaming rollers that have a concave shape. These rollers are mainly used to create double seams. Setting up the rollers is a complicated job, and this is the part where people usually mess up. Having an incorrect set up in the first seam roller will result in the entire process getting compromised.

Sealing Chamber: Also called the vacuum room, this is the section where sealing is done by removing oxygen from the can first before applying the lid on top. The removal of oxygen is done in a vacuum room under the application of vacuum pressure which expels all the air, making the can perfect for storing any type of perishable products. This is the chamber where the structural integrity of the seaming process is assured.

Ejector: This is a rod that comes equipped with a small disc on one end that emerges from the center of the seaming head, moving vertically, ejecting the can once the seaming has been done. The ejection has to be done carefully to avoid leaving a visible dent on the sealed can. It also helps to maintain the placement of the lid on top of the can.

Feeder Caps: These are automatic robotic arms that pick lids from a huge pile of them, transporting them to the sealing station where they are applied to the cans. The process is automated to increase speed and accuracy.

Transport: These are power converters that move continuously, transporting the filled can and containers into and out of the sealing machine. They ensure that the entire process, from start to finish, moves in a seamless fashion without any interruptions.

Types of Can Seamer Machines

Servo Fixed Speed Sealing Machine

The world of can seaming machines is limited. There are only two main types that are used in the packaging and manufacturing space around the world, and they are based on two dominant factors.

Based on Machine Automation

Under this category, we have a fully automatic can sealing machine which doesn’t need much input from people. A good majority of their operations are automated, and the only thing the operator needs to concern themselves with is supplying the lids in bulk and feeding them into the machine. This type of can seamers are very first accurate and can handle a lot of work in a short period of time. They are ideal for companies that require high volume production in order to meet high demand.

There are other variations under this called the semi-automatic can seamers that need the operator to take on more roles like initiating the process and feeding materials into the machines. Semi-automatic seamers are not that fast and can handle one container at a time. But they do pack some high-level accuracy. They are ideal for a small production in homes and for hobbyists.

Based on Machine Design

Based on the design of the machine, we have the rotary machine, which functions by rotating on its axis to seam the can. They are also automatic, but they are much faster and ideal for producers who are dealing with high-volume products. Some come with over 18 seaming heads, which allow them to handle several cans at the same time.

Another variation is the non-rotary seaming machine which functions in the opposite direction. Instead of rotation, it is the can that is held stationary as the seaming process is conducted. This is much safer compared to the other processes because there’s minimal damage to the cans, which ensures that the products inside remain untouched. The non-rotary machine is best suited for liquid-based products as they are good at handling spillage.

How a Can Seaming Machine Works

Can seaming comes in varying types and uses varying techniques to get the job done. However, as previously mentioned, the principle behind their functioning is almost the same. On a general scale, seaming happens in three main stages.

Stage 1: Compression

This is where sufficient force is applied to hold the body of the can firmly against the seaming head. This is to allow the chuck to grip the lid in order to attach it to the body later on. This then proceeds onto the turntable that pushes the body of the can in the upward direction towards the chuck. Once the lid being held by the chuck comes into contact with the opening of the can, the seaming process kicks off, interlocking the edges of the lid and the can to form a smooth hook. This interlocking technique is handled by the two seaming rollers that usually come along with the machine.

Stage 2: First Roller Operation

This is the first of the roller operations that are necessary for making the seam complete. The first one is the most crucial because the hook that results from this will determine how the final seam will hold. The machine starts by pushing the flange of the can lid; this forces the flange to fit on the can. The roller keeps pushing it towards the chuck. The id is then interlocked with the body of the can, but that’s not tight enough to consider the contents in the can safe.

Stage 3: Second Roller Operation

The second roller operation immediately kicks into gear once the first one is done. It irons out the loose double seam from the first process, ensuring that a fool-proof seal is placed on the lid through pressurized compression. The machine then squeezes the sealing on the open space left to create a solid double hematic seam that now makes the seal complete. Only forceful action would be able to pry it open.

Double Seaming

Canned Motor Oil
Source: Unsplash

When it comes to packaging, cans are considered the best bets for storing perishable goods, and among the techniques that exist, double seaming is the most effective one. Double seaming locks in the contents, keeping them away from micro-organism and oxygen, which usually contribute to damage and contamination.

A double seam is achieved by folding the end of the lid, curling them into each other to make two layers of folds that are squeezed into each other. What this means is that, for the can to be opened, you have to unclamp two layers of metal, and that takes considerable arm strength. In a nutshell, a double seam can only be opened by a person who is actively trying to open the can. It may fall to the ground, and the seam won’t even budge.

How is a Double-Seam Made

A double seam is made inside a can seamer through the use of a seamer head that is composed of a chuck and two operational rolls. The process begins with the chuck holding the lid in place as the body of the can is pushed into it. As the lid is kept in place in position by the chuck, the first operational roll comes around to create the first seam.

The second roll follows next immediately, and it tightens up the first seam. The end of the lid is compounded and transformed into a seal that looks like a gasket which ensures the lid is closed completely over the first seam. All this is made possible without allowing any loss of internal pressure or allowing any air to sneak in. Once the double seam is in place, no material can get in or out without a physical breach, and that takes deliberate action.

Benefits of Double Seaming

Sealed Cans
Source: Unsplash

There are some perks that come with double seaming. A lot of manufacturers and packagers who deal with perishable goods tend to go with double seaming compared to other techniques for the following reasons.

Double-seaming provides extra protection for the contents inside as it would take considerable force to pry the lid open. The seal is usually airtight, with no space for anything to sneak in or out. Once the double seam is set in place, only a can opener can dislodge it.

Double seaming is more economical compared to single seams. It may use an extra layer and take slightly more time, but it ensures the contents of the can are able to stay much longer on the shelf. The longer the can is able to withstand the elements, the higher the chance that it would be bought.

Double seaming prevents leakages from the inside. The protection that stops things from getting in also keeps the contents of the can from leaking outside. Outside a physical breach, there’s nothing that can cause the can to start leaking, and that’s good news for consumers.

Applications of Double Seaming Machines

Source: Unsplash

Double seaming machines are used for many applications in the manufacturing and packaging industry, with food and beverage taking the cake due to their perishable nature. The following are some notable applications of double seaming machines in the industry right now.

Beverage: All types of drinks and beverages that use tin cans and glass bottles make use of double seaming to ensure that the contents inside don’t come into contact with the elements during their duration on the shelves. This not only keep the content inside safe for consumption, but it also gives the cans their iconic appearance that ahs come to be associated with soft drinks and canned foods.

Food: The food industry is the biggest beneficiary of double seaming. Food being highly perishable needs to have as much time on the shelves as possible. Double seaming is the best way to ensure that this is pulled off. The level of air-tight sealing attained by double seaming makes it hard for anything to move in and out of the sealed container.

Pharmaceuticals: Drugs also require an environment that is free of contamination for them to work, and double seaming is the most used method to ensure that this is possible—some of the drugs that require this range from medical powders to pills and other medical supplies.

Chemical Industry: Where chemicals are involved, the concern is usually more about keeping things inside. Chemicals can be toxic, and to stop them from being released into the environment, they are stored in chemical cans that are double seamed for extra protection. Some common chemicals that undergo this packaging process include cleaning liquids, farm chemicals, lacquers and inks, glue, among many others.

Double Seam Defects

Profound and reliable as it may be, double seaming has its own drawbacks. Most of these defects are visual, but some have a thing or two to do with the structural integrity of the cans. The following are some common double seam defects that you should be aware of.

Cut Seam: A cut seam happens when the seam applied is too tight to the point where you can see viable cracks and fractures on the outer layer. One common cause of this defect is having one or both seaming rollers too tight. It can be rectified by a simple loosening during the seaming roller section.

Droop: A droop is that overhanging piece of metal that is visible from the bottom of the seal. It makes the bottom edge of the can look like it has a scalloped shape. It happens due to the application of immense pressure in the turntable. To rectify the situation, simply decrease the pressure in the turntable and loosen the roller operations. Replacing worn-out seaming rollers is also another option you can try if others don’t work.

False Seam: A false seam is the most serious defect as it compromises the contents of the can. It is a situation where the lid is compromised and doesn’t close properly, leaving space underneath it to allow for leakage and contamination. Possible causes of this include the use of already damaged lids or overfilling the can. Always check the quality of the lids before feeding them into the seaming machine.

Incomplete Seam: This is a situation where a section of the seam remains unfinished, making the entire thing a little loose. It may continue to hold for a while, but when subjected to pressure, for example, a fall, the lid will come flying off, sealing the contents. A common cause of this compilation is the use of too low or too high pressure in the turntable. To stop this from happening, read the instructions on the can sealer for the recommended spacers. You can also check the seaming chuck for signs of damage; replace it immediately if you notice defects.

Sharp Seam: This is a very sharp seam edge that appears under the seam, and you can even feel it when you run your fingers below it. It is usually an indication of a fracture in the seam, which can compromise the quality of the contents inside. The leading cause of this defect is using seam rollers that are too tight or having the pressure too high in the turntable. Loosen the rollers and reduce the pressure on the turntable, and everything will work perfectly.

Vee: A vee is a pointed and sharp overhang on the bottom edge of a normal seam. The appearance of the vee is an indication that the edges on the body and the lid of the can didn’t interlock like they were supposed to. Using too much pressure in the turntable is the biggest culprit here and reducing the pressure is one way of ensuring the defect stops popping up.

Considerations When Choosing Your Can Sealing Machines

If you are planning to start your own can seaming operation, there are some specific machines you will need. But making that choice can be a little hard due to the many options available in terms of brands. To help you navigate this, the following are the factors you have to keep in mind during your search.

Your Needs

You have to first figure out your production needs. How big is the production volume? How big is the demand? How much space do you have? These are some of the questions that will help you get a clear image of the machines you need. The demand, for instance, is what will help you decide what level of automation you will need. The space available will help determine the size and number of machines that will be able to fit. Take time to assess all your resources at hand first.

Your Budget

Depending on the size of your operation, you may need a significant injection of funds to get things running. You can only get what you can afford, and if you’re limited in the capital, you may have to resort to a limited packaging capacity. The best seaming machines don’t come cheap, and you will also need specialized operators to run things; they too will demand huge salaries. If this is the route you have chosen to go, make sure you have enough capital to get things running.

Future Upgrades

You may start small due to budgetary constraints, but that doesn’t mean you will remain small scale for the rest of your days. At some point, you have to upscale your operations, and this should reflect in your choices. Start with machines that can be upscaled quickly without being rendered redundant. It would cost you less to get a can seaming machine that can accommodate your growth rather than one that will force you to buy new ones again.


All machines are mechanical, which means wear and tear is part of their itinerary. However, that should not stop you from going for the toughest of the lot. They will cost you more but having a machine that lasts your years is a better long-term investment as that ensures your returns before it finally croaks. You should also pay attention to the warranty terms. You must have the freedom to return a machine that breaks down too fast and get a replacement or a refund.


Packaging is an important arm of manufacturing, and among the many types that exist, canning is the most widely used one. The need for a proper seaming machine cannot be understated because it pertains to the safety of consumers. If you have been thinking of starting your own can seaming company but have no clue on what direction to take, check out our website and have all your questions and concerns addressed by our team of experts.

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