Volumes of production

Suited to mass-production.

Unit price vs. capital investment

In-mold decoration is very cost-effective compared with painting or spraying parts in a separate process.

Speed

As you might imagine, inserting the film has a slightly negative effect on the overall cycle times, but this step can be automated and it needs to be considered in relation to the time it would otherwise take to decorate a part by, for example, painting it.

Surface

Different films can be used to give a variety of finishes ranging from the functional to the decorative.

Types/complexity of shape

In-mold decoration can be used on both simple and complex compound curves.

Scale

As injection molding (see p.196). It is possible to make very small parts, but the shapes need to be very simple.

Tolerances

Not applicable.

Relevant materials

Polycarbonate, acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polystyrene, and polypropylene.

Typical products

In-mold decoration is not just limited to text-based graphics, but is also used to produce color on moldings and to add surface patterns. One of the most interesting (albeit invisible) foils that can be applied is a form of “self-healing” skin. This protective layer helps to keep handheld products, such as cell-phone casings, shiny and free from scratches. Other applications include decorative cell-phone covers, machine fascia, digital watches, keypads, and automotive trim, to mention just a small selection of products.

Similar methods

Over-mold decoration (p.214) is similar, but involves the application of materials, rather than foils, to a molding. Sublimation coating is another alternative, although it is applied as a secondary process after molding and is particularly suited to engineering polymers such as nylon.

Sustainability issues

By combining decoration with production, energy consumption can be significantly lowered as there is no additional machining, power use, and transportation. In addition, the decorative films can be used to enhance and protect the material surface, which can prolong the life of the product.

Further information

www.autotype.com.sg

www.filminsertmoulding.com

www.idt-systems.com

Over-Mold Decoration

Product	E-Go laptop
Designer	Marcel van Galen
Materials	fabric over a plastic molding
Manufacturer	Tulip
Country	The Netherlands
Date	2005

The internal plastic molding of this laptop computer can be over-molded with a range of different materials to suit varying consumer markets. The leather and fabric “skins” allow for consumer electronics to be marketed in the same way as more fashion-led products, such as handbags.

Over-mold decoration is not really a method of production in is own right, but rather an extension of standard injection molding (see p.196), as part of a two-step process. What is particularly noteworthy about it is that it can give plastic components an almost craftlike quality by the way it cleverly allows a different material to cover the plastic in the mold.

If you were to see a cell-phone casing, for example, that has a small patch of fabric wrapped onto its surface, you might find it an interesting combination and imagine that the addition of the fabric would require a whole new process involving someone fixing the fabric by hand onto the plastic molding. In reality, this would be labor-intensive and expensive. Inclosia Solutions, a branch of Dow Chemical, has come up with the technology to combine plastic with a range of other materials during the molding process itself, eliminating the need for any secondary finishing.

The benefit of this type of manufacturing is that it provides designers with a new set of materials, surfaces, and finishes to challenge traditional notions of plastic-molded products. Instead of electronic products having the same all-over plastic skin, they can have warm, tactile surfaces that are closer to textiles or to crafted materials such as wood. The process offers the possibility of extending our perception of products beyond the current boundaries of identical, mass-produced plastic, making it feasible for products to be “dressed” and become more integrated with our clothes, furniture, and jewelry.

–  Automated method of covering plastic-molded components with a second soft, or decorative, material.

–  Cost-effective alternative to hand assembly.

–  Compatible with most engineering thermoplastics and elastomers.

–  Although over-molding provides benefits when it comes to surface decoration, it is a two-step process, adding to unit price.

–  Can require trial and error when using untested materials.