In-Mold Decoration

The process of applying labels or decorations to plastic articles simultaneously with the molding operation by which they are formed. Two basic, methods, each with many variations, have been used. The first employs a pre-printed label of plastic film, paper of cloth which is positioned in the mold prior to molding. During the molding cycle, the label or its printed image fuses to and becomes an integral part of the article.  In the second basic method, the image is printed directly onto the mold surface with wet or dry ink, or applied to the mold by an offset process.  In-mold decorating processes can be used in injection molding, blow molding and casting operations.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).


Injection Blow Molding

A blow molding process in which the parison is formed over a mandrel by injection molding, after which the mandrel and parison are shifted to a blow mold where the remainder of the cycle is completed.  While the part is being blown, cooled and ejected, another parison is being injection molded.  Advantages of the process are that a completely finished part is formed requiring no post finishing operations, closer tolerance are possible, and parison wall thicknesses can be varied at desired areas. First used to make small medical and single serving bottles, injection blow molding is now widely used for all types of plastic bottles.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).


Injection Molding

A molding procedure whereby a heat-softened plastic material is forced from a receptacle into a relatively cool cavity which gives the article the desired shape.

Injection molding has seen steady growth since its beginnings in the late 1800's. The technique has evolved from the production of combs and buttons to major consumer, industrial, medical, and aerospace products.  In 1868, perhaps in response to a request by billiard ball maker Phelan and Collander, John Wesley Hyatt invented a way to make billiard balls by injecting celluloid into a mold. By 1872, John and his brother Isaiah Hyatt patented the injection molding machine. The machine was primitive yet it was quite suitable for their purposes. It contained a basic plunger to inject the plastic into a mold through a heated cylinder.

Revolutionizing the plastics industry in 1946, James Hendry built the first screw injection molding machine with an auger design to replace Hyatt's plunger. The auger is placed inside the cylinder and mixes the injection material before pushing forward and injecting the material into the mold. Today, almost all injection molding machines use this same technique.


Ionization Foaming

The process of foaming polyethylene by exposing it to ionizing radiation which evolves hydrogen from the polymer, causing it to foam.