Printing graphics on aluminum cans is a challenging process. It involves individually applying up to five colors with separate rollers, baking the colors on with heat, and then applying a layer of varnish to keep the colors from being rubbed off. Alternatively, the printing process may use special chemicals and a UV setting process. The complexity of these methods may be a surprise to some because of the shocking abundance of aluminum cans on just about every store shelf all around the world.
So how do all of these companies deal with the challenging process of printing on aluminum cans?
Aluminum is a smooth, nonabsorbent surface that requires a bit of chemical wizardry to hold pigments. For this reason, some smaller manufacturers forgo these printing challenges and instead opt for shrink-wrapped plastic sleeves on their cans.
The same challenges, and more, apply to printing codes on those shrink-wrapped cans. Since brand recognition doesn’t depend on the lot number, it may seem like there is less incentive to use an appropriately-researched process to print these codes. However, complying with regulations and maintaining quality depends on these codes, so an effective solution must be found. Let's take a deeper look at how to print on aluminum cans and discuss some of the best solutions to this challenge.
The Challenges of Printing on Aluminum Cans
The majority of the printing and varnishing of aluminum cans takes place when the cans are first manufactured from aluminum blanks. The beverage or food maker orders the cans in bulk from a company that specializes in making, printing, and distributing empty aluminum cans in a variety of sizes standardized by the industry. The printing and finishing of the can take place in a dry manufacturing environment in an area that is carefully controlled to ensure the optimum set of the printing. However, the same is not true of codes printed on aluminum cans later in the production process.
The codes printed on aluminum cans are usually a lot number and a date. The lot number is for quality control purposes. For example, if the batch is found to deviate in taste or has any safety concerns, the manufacturer can track down items from that batch and destroy them. If contamination of products occurs between the manufacturer and the consumer, these lot numbers can provide a basis for the manufacturer to track down its source. If only part of a batch is contaminated then it likely happened outside of the manufacturer’s facilities.
Alternatively, if whole batches or multiple batches were compromised, the manufacturer will need to investigate its ingredients suppliers. The date coding can serve similar purposes or serve to let a consumer know that a product is still safe to consume. In either case, the coding will have to be printed on the aluminum cans after they are filled. And, this printing will take place in the considerably more difficult environment of a food or beverage processing plant.
The challenges of printing on aluminum cans may include:
- Heat: Canning of many food and beverage products involves bringing the product and can to temperatures above boiling point while under pressure to sterilize it. Residual heat may linger and can affect how ink bonds to the can.
- Cold: Acidic products like beer, wine, or juice may not need heat sterilization to kill microbes, as the acidity of the product prevents their growth. These products may be bottled cold to preserve or give character to their flavor. Cold too can affect the properties of aluminum and how printer ink will bond to it.
- Moisture: Moisture is a common element in many canning operations. Steam washing is a common way of cleaning cans before they are filled. Changes in temperatures, like rapid cooling, can cause condensation on the surface of a can. This can prevent ink from touching the can’s surface, dilute the ink, cause smearing, and otherwise create illegible codes.
- Spills: Products overflows and splashing or stray droplets are relatively common in food processing. These can contaminate a can’s surface and interfere with the printer’s ability to print legibly.
Printing legible codes on aluminum cans requires innovations in both chemistry and mechanical application. Different formulations of ink can bond with aluminum and dry incredibly quickly despite—sometimes extreme—variations of heat and cold. Dealing with moisture or other surface interference is part of the application process. A quick but forceful blast of air can push moisture and other fluids out of the way and dry what remains to allow the ink to contact the can and for a clean, clear printed code.
How to Print on Aluminum Cans for Efficiency and Clarity
Continuous inkjet printing (CIJ) was developed to provide a way to efficiently and clearly print on aluminum cans. CIJ printers provide the best solution for coding aluminum cans because they:
- Provide high-quality codes from a variety of ink types (to suit your unique production conditions)
- Can keep up with the high speeds of large canning operations
- Are able to print on flat or irregular shapes
- Can print directly to products and/or end-of-line packaging
InkJet, Inc. offers a robust, modular CIJ printer that is capable of working in harsher environmental conditions (e.g., some heat and humidity) and can code up to 1,050 feet per minute.
DuraCode is a compact, modular CIJ printer with a built-in touchscreen and keyboard. It’s a rugged printer that meets the needs of high-demand and high-volume printing tasks, like those found in beverage and food canning plants. Its flexible print head can be mounted vertically, horizontally, or at other angles to print on aluminum cans to meet retailer requirements for vendor coding. It is also an easy-to-use system with quick-swap inks and filters that keep the production line running.
InkJet, Inc. provides assistance setting up the DuraCode CIJ printer on beverage and food production lines. We back the DuraCode long term, with a selection of inks and fluids to print on aluminum cans in diverse environments and under a wide range of temperature conditions, from extreme cold to heat. InkJet, Inc. knows how to print on aluminum cans in the food and beverage industry with efficiency and expediency, ensuring full legal compliance.