|
A new approach to product decoration
Film Insert Moulding (FIM) offers plastic moulding companies the opportunity to produce products with greater efficiency and at reduced costs. Richard Townsend, Product Manager for MacDermid Autotype, explains the processes involved and discusses the benefits of the technology over traditional methods of product decoration.
Moulded plastic products with high quality and often intricate decoration are now commonplace, from mobile phone handsets and mp3 players, to satellite navigation units and in-car entertainment systems. However, conventional methods of product decoration, which are typically applied post-mould, can involve complex combinations of processes and multiple component parts, adding significantly to production costs.
By comparison, a rapidly evolving technique known as Film Insert Moulding (FIM), whereby three-dimensional components can be efficiently formed and decorated, can considerably reduce the number of production stages and component parts necessary, cutting both time and cost, while at the same time improving the appearance, quality and durability of finished products. FIM can also offer manufacturers increased flexibility, in terms of design and manufacturing options, over traditional decoration methods such as spray painting, laser etching, appliqué, water transfers and pad printing. Both shallow and deeply drawn profiles can be achieved easily, enabling innovative eye-catching designs to be realised cost-effectively.
How does Film Insert Moulding work?
Film Insert Moulding is a relatively simple process comprising four stages: printing, forming, cutting, and moulding.
First, the required decoration is printed onto the film substrate to be moulded. The image is typically screen printed on the second surface of the film to ensure that it is protected against exterior abrasions by the scratch resistant hardcoated outer surface.
Once the image has been printed, the film is ready to be formed into a 3-D component; forming methods include vacuum forming, hydro-forming and high pressure forming. During this process the fla t printed image is being shaped over a single part tool using positive or negative pressure. Thermo-forming uses heat and vacuum to form the film over a tool, as opposed to stamping it into shape, thus reducing the potential for distortion of the image and enabling the material to retain its optimum strength. An alternative method is matched-metal tooling, whereby both a male and female die are used, although this process can potentially damage the image or film and result in problems if the finished product is backlit.
In the third stage of the FIM process, the 3-D images are cut from the waste film, ready for moulding. Highly accurate die-cutting is typically used to trim the films three-dimensionally, so that the cut image can be effectively moulded. Precision cutting is crucial to the quality of the finished product so it is not unusual for a number of iterations to be tested before this process is carried out.
Finally, the 3-D shapes are injection moulded to produce solid three-dimensional components featuring high quality graphics that are also resistant to scratches and abrasions. Due to the criticality of this final stage, the mould should always be designed for the specific FIM component, rather than re-used. In order to ensure that costs are minimised, forming or moulding tools should be formatted to maximise the number of parts that can be produced in each production cycle.
Why FIM?
Film Insert Moulding enables manufacturers to lower significantly the production costs associated with traditional production methods, through streamlining processes and, therefore, reducing the time and resource required to produce high quality components.
For example, whereas a conventional mobile phone handset contains a variety of components, using FIM an equivalent product can be quickly produced as a single unit incorporating the lens, body and keypad. Similarly, in the outer case for a personal CD player there may be up to eleven different components, including etched metal labels, metallised buttons, and a moulded case and display area, and involving approximately twelve separate production processes, such as spray painting and hard coat, pad printing, screen printing, etching, etc. Using FIM, it is possible to reduce this number to a single component, with only eight production processes being required (including printing, forming, die-cutting and injection moulding), resulting in considerable cost and time savings.
Screen printing with the FIM process, as opposed to spray painting with conventional methods, enables extremely fine print definition, for example, to simulate wood or carbon fibre effects commonly seen in automotive components, while the use of special varnishes, overprinted during the first stage of production, enable textured and gloss finishes to be selectively created around or on control knobs or switches.
The right film
The effectiveness of the FIM method of producing high quality decorated components is largely dependent on the quality of the film used. Specialised film substrates have been developed to offer properties such as the ability to support intricate graphics, using a range of inks; to be shaped using pressure, vacuum forming systems; and to provide resistance to surface abrasion and cleaning with chemicals. In addition, they can be used for extended periods in sunlight, have high levels of transparency, so that backlighting can easily be incorporated, and can be surface embossed or textured.
The latest generation of films such as XtraForm from MacDermid Autotype, is their ability to be deep drawn. This means that products with significant depth can be produced without affecting their mechanical or physical properties. Using FIM, deep drawn components can be produced to a high cosmetic standard, avoiding problems such as surface cracking.
In conclusion
Incorporating Film Insert Moulding production methods can enable plastics moulding companies not only to reduce operating costs, through streamlined processes and decreased component parts, but also to reach new customers. By working closely with designers and screen printing companies, manufacturers can produce high quality components that simply aren't possible or cost effective to make using conventional methods, opening up whole new markets.
|
