With insert moulding, preformed, blanked out embossed sheets, also known as inserts, are inserted into the injection mould, and rear injected. However, this involves an additional operation before the forming process proper. The imprinted hot-process embossed sheet is formed and then blanked out to the right contours on a roll by a thermoforming unit in most instances. The benefit is a higher three-dimensional degree of freedom of the later inserts. Slight undercuts on the component edge, bends up to a defined threshold radius, bulges or similar can be represented. The blanked out inserts are fed to the mould by means of a robot system. As opposed to other decoration techniques (such as IML or IMD) the hot-process embossing films are much thicker and more stable. Thus, no “adherence“ in the cavity for contour matching is required. Still, a vacuum circuit prevents the insert from falling off during the closing movement in most instances. As usual, the inner boundary layer of the insert melts / combines with the plastic material through the prevailing pressure and temperature such that the end product is decorated ready for use when it is unloaded.
- The film / decor is imprinted by means of a variety of possible printing processes.
- The thermoplastic film is heated to the pre-forming temperature.
- The component is formed, cooled and blanked out to be an insert ready for use.
- The inserted insert is rear injected inside the mould.
- The finished part is unloaded while a new insert is loaded at the same time.
This technology is preferably used for thick-walled applications with imprinted symbols or inscriptions, or for components where the lateral edges are very wide and are also to be decorated. Washing machine panels, enclosures for electrical appliances, stressed orifices for automobiles are examples of these applications. Sometimes high requirements are made on the scratch resistance, look and feel of surfaces. Such requirements can hardly, if at all, be satisfied by film of painting systems.
- Components with a complex geometry (such as bends, wide edges)
- Components with stressed surfaces (such as chemical, mechanical)
- Components with haptic or optical surfaces (such as soft touch, hologram)