Printing or marking on metals is not easy. Metals have a non-porous surface which means that liquid won’t absorb into them. By contrast, printing or marking paper is easy because it is a porous surface, where ink easily sinks into the material to leave a permanent mark.
Printing on metals requires an extremely quick-drying ink that hardens to the surface of the metal rather than absorbing. Quick-drying ink is necessary for accurate printing on metal to avoid smudging or excessive dot gain.
Challenges of Inkjet Printing on Metal Surfaces
Kao Collins has produced standard and customized inkjet printing on metal surfaces for a long time, especially on stainless steel and printing on aluminum.
Inkjet Printing on Coated Metal
If your business requires fast and precise printing on any metal surface, whether it’s aluminum, stainless steel, or any other similar substrate, the first step in determining the right ink is to know whether the substrate has a coating atop the metal, which is often the case.
The process typically starts by receiving a metal sample when customers reach out, inquiring that they are printing or want to print on metal. More often than not, the metal is coated, which makes a big difference. It’s difficult, but not impossible, to print directly on a metal surface. The ink used, then, is applied to the coating, not directly on the bare metal—the coating functions as a primer. Most inks are printed on coated metals.
The most common of these metals to be printed on is aluminum. It’s light, flexible, and doesn’t rust. It’s commonly used for signage at trade shows, as well as point-of-sale displays. Aluminum can also be printed in wide-format flatbed scanning printers.
Inkjet Printing on Uncoated Metal
There are limited options for printing on uncoated metals. The first is to use a primer base. Companies printing a wide range of products often apply primers rather than choosing a specialty ink. It is more cost-effective because changing inks isn’t necessary.
Companies specializing in printing on hard surfaces, like metal or glass, may choose to use light-cured inks. When exposed to mercury arc lamps, cationic inks continue curing after the initial exposure to the light, which excites the ink molecules until they exhaust all their energy — making the ink lock to the surface.
Non-cationic inks shrink and curl on a microscopic scale as it cures, making them a less durable solution because they are more susceptible to scratching and peeling. Cationic ink doesn’t shrink when it cures.
Inkjet Printing on Flexible or Bending Metals
Various inkjet inks are ideal for printing on metal surfaces that bend or are flexible, such as aluminum wrapped around a pillar or other shape. Kao Collins produces specialty inkjet inks that can withstand bending up to about 180 degrees.
Inkjet Solutions for Printing on Metal
Our Inkjet solutions for printing on metal vary from cans, chrome-plated metal surfaces, coated or uncoated metal, and more.
Common Metal Substrates for Industrial Printing
Inkjet printing is an effective solution for embellishing metal products. A craft brewer, for example, may want to personalize a beer can for a special occasion or seasonal release. As the go-to solution for customized jobs, only the imagination limits the possibility of inkjet printing on metal and other hard surfaces, including:
- Stainless Steel
UV Inkjet Printing on Aluminum Sheets & Stainless Steel
The most common metals printed are aluminum and stainless steel. Printing on these specific metals with industrial inkjet systems is challenging because these surfaces are commonly exposed to extreme conditions, such as water, UV light, grease, oil, and other chemicals–not to mention the need for flexibility, abrasion resistance, and fade resistance that results from extended exposure to these conditions over long periods of time.
When choosing an inkjet ink to print on aluminum or stainless steel, look for these performance characteristics in the inks available:
- The ink can be exposed to extreme temperatures.
- The ink can withstand contact with certain chemicals (oils, grease, acids, etc.).
- The ink can be bent or stretched without cracking.
- The ink is colorfast, producing vibrant, vivid colors that print accurately on reflective metal surfaces.
Applications for Industries
- Aerospace and defense industries often need to print on metal components such as parts for aircraft engines, structural parts, aircraft fittings, and more.
- Automotive marking and coding for supply chain tracking and printing on end-user metal automotive parts.
- Consumer-products manufacturers rely on inkjet printing for printing control panels, knobs, controls and other components.
- Medical-device manufacturers rely on inkjet printing to categorize devices with marking and coding.
- Marine industry products like oxygen cylinders etc. require precise marking and coding for supply chain tracking and expiry dates.
- Art & Sculpture metal print has become an essential element in today’s market. Several different printing processes have been adapted to their needs.
- Architecture metals used for architectural purposes include lead for water pipes, roofing, and windows; tin, formed into tinplate; zinc, copper, and aluminum, in a range of applications including roofing and decoration; and iron, which has structural and other uses in the form of cast iron or wrought iron, or made into steel, etc. all require marking and coding.
- The most common metals in construction use inkjet printing on carbon steel, aluminum, copper tubing, and stainless steel,
Available Inks for Printing on Metal
Industrial inkjet printing is also the perfect solution for printing on metal. Printing inks for metal provide very high scratch resistance, resistance to hand and machine washing, and resistance to chemicals and solvents like hydrocarbons, alcohols, greases, and oils.
Choosing the best industrial inkjet ink requires considering the following factors:
- The type of metal
- Any precoating or primers
- End-use of the printed product
- Exposure to environmental conditions
Solvent Based Inks for Printing on Metals
Solvent-based inkjet inks are effective for printing on metal because the ink “bites” into metal surfaces.
Inks for Funai Technology
Dye-based solvent inkjet ink for non-porous fast-drying surfaces and high sharpness offers good adhesion on metal, with low maintenance requirement. The ink does not dry to the printhead. An ink such as NEXXO from Kao Collins prints high-resolution 2-D codes on curved surfaces.
Inks for HP Technology
The SIGMA solvent-based TIJ ink may be used for some metals, including foils. The ink cures quickly and has a 12-hour decap time. These inks are packaged in genuine HP 45si cartridges. With a sample of the metal substrate, Kao Collins can evaluate which ink would be best.
Water-Based Inks for Printing on Metals
Certain specially engineered water-based inks are suitable for industrial inkjet printing on metal surfaces. Until recently, water-based inks couldn’t print on metal and non-porous surfaces. Nanodispersion water-based inks increase pigment concentration, so the ink spreads evenly over the surface, drop by drop. LUNAJET from Kao Collins reduces ink on the metal surface, which allows for rapid drying and smooth, superior printing results with vibrant colors.
Curable Inks for Printing on Metals
While solvent ink and water-based inks are more commonly used for printing on metal, the new enhancements in UV inks have widened the scope of appeal and applications for printing on metal. Thanks to the improvement in UV inks’ raw materials, the range of UV curable inks for printing. UV-curable inks, such as C-Lok ink from Kao Collins, have expanded the possibilities of high-resolution printing on metal with increased durability, rapid curing, and sustainability.
Primarily used for food cans, beverage cans, aerosols, closures, caps, and industrial cans, LED-curable inks are effective for metal decoration. High-performance LED curable inks are fast drying and also environmentally friendly.
Ultraviolet or electron beam (EB) curable ink supports printing on metal with faster changeovers, high reliability, and excellent print quality. Additionally, these inks are insensitive to water or solvent. Full coverage clear coatings may be used in place of lamination. EB inks also offer cost and sustainability advantages.
Choosing the best inkjet ink option for your metal and printing technology
Contact Kao Collins to help you decide the right inkjet inks for printing on metal. We can create custom formulations for specific needs and color matching.