Considerations for Inkjet Printing on Anodized Aluminum Parts
First used within an industrial context in 1923, anodization is an electrochemical process that improves the durability of a metallic surface. Anodization is a common way for metal part manufacturers to strengthen their products, protect them from corrosion, and make them easier to dye.
Although one can anodize a variety of nonferrous metals (e.g., magnesium, titanium, zinc, etc.), aluminum is the most frequently anodized material as its properties are conducive to creating strong anodic oxide films.
The strength and aesthetic versatility of anodized aluminum have led to its use across a variety of industries. While anodized aluminum has been used by artists as a unique canvas, it is commonly used by NASA to construct the International Space Station’s truss structures.
Today, anodized aluminum is frequently used by those in aerospace engineering, automotive production, and consumer good manufacturing. The use of anodized aluminum isn’t the only commonality between these fields—they also share a need for direct part marking. 1D barcodes, 2D data matrices, lot codes, and more are all applied to anodized aluminum parts to ensure supply chain traceability and impart important production information for retailers and consumers.
To create these markings, companies frequently utilize inkjet printers for their versatility and ability to make clear, machine-readable codes. Here are a few tips you should consider when inkjet printing on anodized aluminum:
Use Solvent-Based Ink
Like other metals, anodized aluminum is a non-porous substrate. Non-porous substrates do not respond well to water-based inks and are prone to messy and smudged codes. Solvent-based inks are much better suited for metal substrates due to their adaptability, quick-drying nature, and durability.
Continuous inkjet printers and certain thermal inkjet printers are compatible with solvent-based inks. Either one of these options can successfully mark an anodized aluminum surface as long as the anodic coating hasn’t been sealed yet. However, to obtain the best results with either one of these machines, it is important to mark anodized aluminum within an appropriate time frame.
Consider the Time and Environment
It isn’t uncommon for companies to anodize their aluminum parts, mark them a few days later, and then seal them. While one can wait a week and still successfully mark an anodized surface, holding off for two weeks or more can cause issues.
Sealing is a hydration process; users seal anodized aluminum by submerging the material in a chemical bath. Submersion closes the pores on the anodic layer, leaving a strong anodic oxide film. This same process naturally occurs to unsealed anodized aluminum over time. The porous anodic coating absorbs the humidity in the air and starts to seal itself. As the anodic layer self-seals, it becomes progressively more resistant to ink.
Self-sealing is inevitable but can be somewhat delayed with these precautions:
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Limit the parts’ exposure to air by stacking them after they’ve dried.
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Place the parts in a cool room, as high temperatures accelerate the self-sealing process.
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Use a dehumidifier to limit the parts’ exposure to hydrogen as much as possible.
Although these steps can prolong the time frame, they are not capable of indefinitely prolonging the printability of unsealed anodized parts. Make sure to establish a policy that limits the time between anodizing and printing, and create a system to track these intervals.
Use a Printer That Aligns with Your Production Line Needs
Using solvent-based ink and following an appropriate schedule will enable you to successfully mark anodized aluminum. However, to make your operation as efficient as possible, you need to use an inkjet printer that matches your production line’s unique characteristics.
The inkjet market primarily consists of two printer types: continuous inkjet (CIJ) printers and thermal inkjet (TIJ) printers. CIJ printers, such as the DuraCode Touchscreen or DuraCode Keyboard, create pressurized streams of ink that enable uninterrupted, 24/7 operation. The powerful ink propulsion also allows for high speed marking on production lines moving as fast as 1050 ft/min (320 m/min).
TIJ printers are more compact, often weighing around five pounds when equipped with an ink cartridge. The smaller size of TIJ printers makes them ideal for applications where mobility is key. Although TIJ printers do not have the same speed capabilities as CIJ models—the Anser Pro-S’s max printing speed is 394 ft/min (120 m/min)—they deliver the same high-quality codes as their CIJ counterparts.
Simplify Inkjet Printing on Anodized Aluminum Parts with Expert Guidance
As with other materials, inkjet printing on anodized aluminum parts is only possible when you use the correct hardware and ink for the task. If you are unsure of which printer type and ink will better suit your needs, contact InkJet, Inc. to speak with one of our experts. At InkJet, Inc., we've been providing marking and coding solutions for over 30 years and have personally worked with companies all across the manufacturing spectrum.
When you partner with us, we’ll help you find the perfect marking technology to increase efficiency, eliminate downtime, and maintain regulatory compliance. For more information related to inkjet printing on anodized aluminum parts, or any other questions related to printers and ink, contact InkJet, Inc. online or by phone at 1(800) 280-3245.