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Forms of In-Mold Decoration ( IMD)
InMold Decoration (IMD) is a general, catchall, term used to describe any process in which plastic components are decorated during the injection molding process. However, some companies use this term to describe their own specific process, and hence there can be a degree of confusion about the terminology.
A classic IMD technique uses a roll of carrier film material, which is pre-printed with the images to be transferred to the component. This roll is suspended on the mold machine, between the faces of the tool. An indexing system advances the roll, one image at a time, for each cycle of the mold tool. During the molding process, the heat generated causes the printed image to separate from the carrier film and transfer to the plastic component. The image is thus on the first (outer) surface of the component. Hence it may be a requirement to apply some form of protection to protect the image from abrasion. This technique is often referred to as the Nissha Process , after the principal supplier of the technology.
In Film Insert Molding (FIM), the required image is printed on a flat sheet of material such as polycarbonate. The images may be three-dimensionally formed using techniques similar to vacuum forming. These 3D foils are then cut to remove any apertures, and to match the parting line of the mold tool. Finally the foils are inserted into the mold tool and the resin is shot onto the reverse surface. With careful selection of the sheet material, the imaging system and the injected resin, the result can be a robust, three dimensional, decorated component.
Film Insert Molding can be used to provide both first surface and second surface decorated components. In the case of the second surface variant, the printed image must be stable enough to withstand the resin being directly injected onto it. However, the result is a component, which does not require any post-molding operations to protect it from abrasion.
InMold Labeling (IML) is a variant of Film Insert Molding in which the foils are not pre-formed prior to the injection molding operation. Fairly simple 2D foils are used to decorate a flat area on the component. This technique can also be used on 3D components where the depth of draw on the component is relatively shallow. A typical application might be the lens component of a modern cell phone, which has only a subtle curvature.
In addition to these methods, there are a number of post-molding techniques , which are used to decorate plastic components. These include air brushing , aquagraphic technology and various sublimation techniques. Since these can produce components with a similar final appearance, they are often referred to as IMD. Strictly speaking however, this is a misnomer, since the decoration does not take place during the molding cycle.
Information kindly supplied by Pressac Decorative Systems Division. For more information on the company please visit http://www.advanceddecorative.com/
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