Technical Information

Decoration (Printing, Coating)

Printing Technologies for Cans

Offset printing is a major method for printing on metal cans because of its hard and non-absorbent material. The printing methods are mainly classified into two types by their can structure. Sheet printing, using lithographic plates, for metal sheet is applicable to 3-piece and DRD cans. Alternatively, curved surface printing, using plastic letterpress plates (Ref. 2-piece Can Waterless Lithographic Printing) is applicable to 2-piece DWI cans and TULC.

Can's classification Decorative Type Object to be printed Types of Can Printing Method
3 Piece Can Sheeting Printing Coated Metal Sheet Welded Can Lithography Offset Printing
2 Piece Can DRD
Curved Surface Printing Metal Can DWI, TULC, aTULC Letterpress Curved Offset Printing
Lithography Curved Offset Printing
Labeling PET Film TULC Gravure Printing
(1) Sheet Printing
  • Multiple same images are coated on a pre-processed metal sheet, and then the sheet is transferred to the sheet printing machine (the rotary offset printing machine) one by one for printing. A line set up independently from a can forming line.
  • The production process consists of coating and printing. Interior and exterior surface of sheets, such as tin plate, with a thickness of about 0.2 mm and large TFS (tin free steel) plates with a length and width of 1 meter are coated, and then each color is overprinted on each sheet.
  • Production process includes; interior coating -> exterior coating -> printing (multiple times) -> finishing varnishing -> baking and drying
  • Sizing (transparent paint utilizing the metal base for creating a metallic look) and white coating to improve whiteness are used as substrates. After printing, varnish is applied by coating to protect the surfaces and to provide gloss and smoothness.
(2) Curved Surface Printing
  • After forming the can-body, printing on the exterior surface of the 2-piece cans (DWI and TULC cans) is conducted one by one using a curved surface printing machine. Each color of ink is placed on a different (plastic letterpress) plate, and then sequentially transferred to a single rubber blanket (a rubber surface to re-transfer an inked image to a can), allowing all colors to be printed at a time. After printing and just before the ink curing process, an over varnish is applied.
  • The line control system manages automatically production consistency, from can forming to finishing, including printing and coating.
(3) Gravure Printing Lamination
  • A technology that laminates pre-printed PET film onto formed cans using a gravure roll. Gravure printing is a type of intaglio printing (transcript by pouring ink on the engraved sheet), allowing drying and overprinting by color, offering advantages in the reproduction of a wide range of color gradation(smooth color shading)and density.
  • A variety of reproduced effects can be achieved such as photograph quality resolution, metallic mirror-like and pearl-like appearances. This technology is also applied to laminated TULC.
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