Decorating plastic parts is an important facet of our industry, as critical information often needs to be printed onto plastic injection molded parts. Engraving the text or image into the mold cavity is often a preferred method for printing onto plastic injection molded parts, however, there are times where engraving does not stand out enough to be helpful. This is especially the case if the message that needs to be presented is related to safety concerns or if there are multiple message messages that needed to be added to the part. In these cases, decorating plastic parts allows the flexibility to make different text and images in a plethora of colors and finishes. In this article, Rebling Plastics discusses pad printing and hot stamping, two methods that we use for decorating parts.
Pad printing is a low-cost method for decorating plastic parts wherein a silicone pad transmits the image to the plastic part. An engraved plate referred to as a “cliché” containing an etched image of the desired artwork is created from artwork that is either developed by Rebling Plastics or designed by the customer. Afterwards, ink is spread onto the plate and removed, leaving behind only the wet ink in the etched area. A silicon pad then picks up the ink within the etched area and transmits the image to the plastic part. One unique advantage hot pad printing has is that the image can be transferred to irregular surfaces because the silicon pad will conform to the shape of the surfaces during the ink transferring process.
Hot stamping is a decorating process available at Rebling Plastics where a heated die applies pressure to a hot stamping foil that is then pressed against the plastic part. A combination of the heat and pressure from the die facilitates the transfer of the pigment from the hot stamping foil to the plastic part.
One benefit inherent to the hot stamping process is that it can be used on flat as well as round or oval surfaces. Round parts can be decorated around the entire circumference. Meanwhile, oval parts can be decorated on the front and back of the part in one operation using a roll hot stamping machine. Hot stamping is not without its disadvantages too, however, and hot stamping large solid areas should be avoided as air can become trapped between the foil and the part. If a large area must be hot stamped, relief areas should be added to the design to allow for air to escape during the stamping process.