Getting the message across

Critical information often needs to be printed onto plastic injection molded parts. One way is to engrave the text or image into the mold cavity. This requires a one time expense that is low cost if done during the design phase. In some cases, the engraving can be swapped out to make a different image or message. However, in many materials and part designs, engraving may not stand out enough, especially if the message is related to safety. And, sometimes there are so many different messages to add to the part, it doesn’t make sense to tool up and swap out engraved inserts.

Decorating plastic parts

Decorating allows the flexibility of making different text and images in a variety of colors and finishes. Rebling Plastics uses both pad printing and hot stamping for decorating plastic parts.

Pad printing: 

This is a low cost method of decorating plastic parts wherein a silicone pad transmits the desired image to the plastic part.  From the artwork supplied by the customer or developed by Rebling Plastics, an engraved plate commonly referred to as a “cliché” is made which contains an etched image of the desired artwork. Ink is then spread onto this plate and removed leaving the wet ink only in the etched areas.  A silicone pad then picks up the ink in the etched area and transmits this image to the plastic part. A unique advantage of the pad printing process is that the image can be transferred to irregular surfaces since the silicone pad will conform to these surfaces during the transfer of ink.

Tooling for pad printing is relatively inexpensive, requiring only the cliché and a holding nest or fixture to secure the part. This holding fixture also insures the transferred image is located correctly and is consistent from part to part.

Pad printing of multi-colored images is fairly common. Precise registration of the parts is very critical to the success of this process.

Pad printing can be used on most plastics including polypropylene and polyethylene.  Some inks need to be cured at elevated temperature after the ink is transferred while others can be air dried. 

Hot stamping:  

Hot stamping is another decorating process available at Rebling Plastics. In the hot stamping process, a heated die applies pressure to a hot stamping foil that is pressed against the plastic part. The heat and pressure from the die transfers the pigment from the hot stamping foil onto the plastic part.

Hot stamping can be used on flat as well as round and oval surfaces. Round parts can be decorated around the entire circumference while oval parts can be decorated on the front and back in one operation using a roll hot stamping machine. On the other hand, large solid areas that need to be hot stamped should be avoided as air can be trapped between the foil and the part. If it is necessary to hot stamp a large area, relief areas should be included in the design of the image to allow for air escapement.

Hot stamping foils are available in a multitude of colors and finishes ranging from matte to high gloss and specialty foils including holographic and metallic.