IMG gains ground

09 / 2012 - Along with innovative technology and high safety standards, the high quality look of surfaces also plays an important role in modern automotive interior design. Here traditional thermoforming processes are unable to satisfy all of the demands for extremely low grain stretch, the application of logos or decorative fabric elements, as well as matching the grains of adjacent components, along with different grain zones and tight component radiuses.
With the In Mould Graining process, the grain is not transferred to the sheet until the sheet is formed in the thermoforming process. This makes it possible to combine the economic advantages of classic thermoforming technology with the visual advantages of modern moulded skin and lamination technology – and without grain stretch.
Since it was first introduced about ten years ago, the process has been continuously improved by FRIMO through a large number of successful innovations. As a result, it can now be used to create increasingly demanding surfaces and complex component contours.
Due to increasing demands on quality and appearance accompanied by cost pressure, more and more OEMs and Tier 1 suppliers are choosing the IMG process to produce grained surfaces for automotive interiors. That has made it possible to dramatically expand the market share in this technology in recent years. Today IMG is firmly established at nearly all OEMs. Current reference projects include the instrument panel of the Mercedes B-Class and the door trim assemblies of the Volkswagen Scirocco, Golf and Tiguan, as well as those of the Opel Insignia, Zafira, Astra and Meriva, the Toyota Avensis and the Cadillac XTS.
In Mould Graining permits a perfect visual match between adjacent components, which is a topic of increasing interest to designers, especially where it comes to matching door trim with the instrument panel. Along with the grain pattern, this also includes tight component radii and perfect gap dimensions, which other processes cannot achieve with such high quality and cost-effectiveness.
Due to their lower density, the use of in-grain moulded thermoform sheets made of TPO provides a significant weight advantage over a slush skin or spray skin. As weight optimisation is becoming increasingly important with regard to fuel consumption, IMG is also an outstanding solution in terms of lightweight construction.

Further Development of the IMG technology
As a result of continuous further development, the IMG process today can be used for far more demanding, even sharply three-dimensional contours. A 3D simulation makes it possible to verify feasibility early, so that the component geometry and the eventual arrangement of the series production tool can already be optimized in advance. For that reason, it is particularly important that OEMs, Tier 1 suppliers and FRIMO work together in a very early stage of development.
The relevant innovative system details now make it possible to harmonize the sheet thickness distribution to a very large extent, even with sharply three-dimensional parts. Sliding clamp frames in combination with a pre-suction system, for example, can be used to enhance residual wall thicknesses in critical areas. Intelligent clamp frame systems with stretch function minimise the tendency for the slackened sheet to hang during the heating process and reduce sheet thinning by means of specifically defined sliding adjustment. The latest development is the bendable chain guide. Especially when thermoforming components with pronounced three-dimensional contours, there often sharp drawing angles involved, which are liable to cause serious stretching of the grain and the need to use a lot of film. Here the newly developed bendable chain guide helps to achieve much better forming of such geometries. After the film is heated, bending of the chain guide ensures that the film is guided to the mould cavity in the forming station in a way that follows the precise contours. This means that the quantity of film can be reduced while at the same time improving the quality. The reduction in the area of film required (and to be heated) also means reduced energy consumption. FRIMO has filed a utility patent application for this new development.

IMG moulds
Mould-making has also continuously advanced. For example, electro-plated nickel moulds or directly etched steel moulds are used in series production operations. For prototype fabrication, depending on the application, moulds made from special plastic resins, etched aluminium moulds, or sprayed metal moulds are available. Moulds with ceramic surface structure complete the spectrum. These ceramic moulds, in particular, open up promising approaches which can drastically reduce tooling costs and production times, for series production moulds, too.

In Mould Decorating and glueless lamination
With the aim of further simplifying equipment upgrades and facilitating more customization options, the IMG process has been combined with In Mould Decorating. This process, also known as “Deco-Skin”, makes it possible to lay an extremely wide variety of decorative elements (such as fabrics) into the IMG mould and so transfer them to the surface of the component.
With a view toward lightweight construction, economy and sustainability, automotive interior trim is also increasingly making use of renewable raw materials as carrier media. This primarily involves the use of polypropylene-filled natural fibre materials (NFPP), which are also suitable for “glueless lamination”. FRIMO has now combined In Mould Graining with glueless lamination and developed near-series production test moulds for applications such as high quality door trim. This process combination enables the production of very high quality, extremely light trim parts which also implicitly support environmental protection efforts.


The bandwagon is rolling
The trend in recent years shows that, as a process for the cost-effective production of high quality automotive interior surfaces, In Mould Graining is just coming into its own.  Also in view of increasing globalisation, in-grain moulded sheet represents the best solution in many respects. For simultaneous vehicle production at different locations around the world, for example, IMG offers the required robust process technology with global material availability.
FRIMO will also continue to invest further innovation efforts into the advanced development of IMG, among other things in an aim to further reduce tooling lead times and costs and to combine IMG with thin film technology.

Contact for further information and documentation

FRIMO Group GmbH
Martina Schierholt
Hansaring 6
D-49504 Lotte

Phone.: +49 (0) 54 04 / 8 86 - 1 57
Fax: +49 (0) 54 04 / 8 86 - 51 57
E-Mail: schierholt.m[at]frimo.com