FIM

This article has been contributed by MacDermid Autotype

The Film Insert Moulding (FIM) process, also referred to as In-Mould Decoration (IMD), has moved on apace since its introduction several years ago.  In particular, new developments in materials, combined with wider acceptance of the technology by both product designers and manufacturers, have helped to move FIM from an interesting but otherwise niche application to a mainstream production process that is used for a variety of high volume consumer products.

Film Insert Moulding was originally developed as a method of product decoration that could be used to replace traditional post-mould techniques.  Still in use today, these typically involve a lengthy sequence of processes and the need for multiple parts; combined, these factors add significantly to production costs, increase the complexity of each component, and thus the potential for failure, and adversely affect the quality of the overall finish.

FIM uses a simple procedure to overcome these problems, and provides greater product design and production flexibility.  For example, it is easy to produce strong and clearly defined deep and shallow drawn profiles, allowing original and often innovative designs to be considered, and can be used to produce customised versions of high volume parts without cost penalties.

The FIM process involves four steps: printing, forming, trimming and injection moulding.

The component graphics are firstly screen printed onto the underside of a special hardcoated film, then transferred to a vacuum, pressure or thermoforming press where they are moulded to the exact shape of the components being made; the upper or outer side of film effectively becoming the face side of the finished component.

The sheet is trimmed and individual components are cut to size before being moved to the final, injection moulding stage.  Each part is subsequently inserted in a female mould cavity, where molten polymer is injected behind the film to form a strong and high quality part ready for subsequent product assembly.

These simple but effective procedures deliver important benefits, including the ability to create complex high definition designs and produce durable textured parts; as the graphics are printed onto the under-surface of the film, the hard coated substrate forms a tough, scratch-resistant skin over the complete outer of the finished part.  Additionally, as the components can be shaped extremely accurately, with print registration within ±0.2mm, high quality designs can be achieved that are impossible with other production methods.  Similarly, for products such as appliance control panels, it is possible to integrate a decorated enclosure and clear display window into a single component, reducing the materials required and therefore unit costs.

The success of the FIM technique has been made possible by the availability of a new generation of high performance films and inks, that are capable of withstanding the different mechanical and thermal stresses encountered at each stage of the production process.

For example, the latest film substrates, such as those in MacDermid Autotype’s Autoflex Xtraform range, feature a specially developed, high gloss, hard coated surface finish.  The films can be printed using a range of inks; can be shaped using pressure, heat or vacuum; and provide resistance to surface abrasion, physical wear and to chemicals, greases and solvents.  In addition, they have excellent resistance to ultra-violet light, so can be used for extended periods in sunlight, while offering high levels of transparency, so that backlighting can easily be incorporated; they can also be surface embossed or textured.

Perhaps most importantly, the films have been specially developed to offer consistent results when drawn into three dimensional shapes.  The range of films offers varying degrees of workability, from those capable of producing shallow formed fascia panels, to others suitable for deep drawn components such as instrument covers. Unlike conventional film substrates, these films can be shaped without weaknesses occurring or the mechanical properties of the film being compromised, resulting in a high quality uniform finish.

The success of FIM as a modern production technique is being seen in a number of industries.  FIM parts are now used by a number of leading manufacturers of mobile phones and also by car producers; these include Daimler Chrysler, where interior components such as backlit dashboard, lighting and window switches have been produced using FIM as a technique for ensuring a high quality aesthetic finish combined with excellent scratch resistance and optical properties.