Printing on metal

Printing on metal can be done in two ways:  1- Printing on metal digitally or flatbed  2- Offset printing on metal

1- Flatbed or Digital:The best device for digital printing on metal is a flat UV printer, where ink is directly applied to the metal surface, and the print is done. Once the design is printed on the metal sheet, it is dried by UV light exposure.

Before printing, the metal sheets need to be degreased and prepped for ink adhesion. The ink used for metal printing should have good durability; otherwise, it won’t withstand different weather conditions.

There are no size limitations for metal printing, and various images can be printed on different metal sheets. Metal sheets printed with a digital printer should be immediately sent to the curing oven.

Depending on the type of product placed in metal cans, different coatings are used for the interior of the cans.

Digital printing on metal is commonly used for metal plaques, signs, logos, etc.Offset printing on metal is done using lithographic plates and is a primary method for printing on metal cans.

For printing on metal sheets, they need to be coated with an ink-receptive coating before printing and then sent for printing.

The thickness of metal sheets used for printing typically ranges from 0.18 to 0.3 millimeters, depending on the type of work. They are usually first coated with white or clear lacquer to ensure that the printing colors adhere properly.

After printing, the metal sheets undergo varnishing, followed by drying in an oven. Finally, the metal sheets are stacked for cutting and conversion into cans in the can manufacturing workshop.For direct printing on metal (digital flatbed), the file should be in CMYK format with a minimum resolution of 150 DPI.

In digital printing on metal (UV flatbed), the ink is applied directly to the metal surface, and the printing process is carried out.

High-quality inks must be used to maintain color stability, and then the ink is dried using UV exposure.This type of printing is used for directional signs in various locations.

The maximum print size in digital flatbed printing is 250×160 centimeters. Flatbed printing does not require an oven and is cured using UV exposure.

Metal sheets up to 9mm thick with a flat surface can be printed using the flatbed method.UV flatbed printing is resistant to sunlight and rain, and digital flatbed printing offers very high quality with up to 1200 DPI resolution.For direct printing on metal sheets (digital flatbed printing), the sheets must first be degreased and prepped before printing.

2- Offset Printing on Metal:Direct printing on metal is often done with digital flatbed machines. This type of printing can be performed on various metals such as galvanized steel, aluminum, copper, and more.The output from this printing (digital flatbed) is of very high quality and is used for advertising signs and plaques.The cost of direct digital flatbed printing on metal is typically calculated per square meter.This type of printing involves several steps:

• Selecting the material
• Print size
• Primer color
• Printing the design
• Applying protective varnish on the metal

Another type of direct printing on metal is silk printing or pad printing, but these methods have limitations in terms of color, design, and size.This type of printing is used for industries like can manufacturing, metal boxes, and spray cans.

In this process, the desired pattern is taken using film and zinc, and printing is done using an offset printing machine on pre-prepared and degreased surfaces.Offset printing on metal is feasible for high-volume printing.

After the final color is printed on the work, it undergoes varnishing, and the sheets are sent into the oven for color fixation and printing (more details on metal boxes and spray cans will be explained in subsequent sections).