Decorative Technology Adds Pizzazz To Cell Phones And More
A young man punches the buttons on his car radio looking for a favorite tune, a woman waiting at an airport works on her laptop, and a teen-ager just home from school chats on her cell phone. All three individuals are familiar with the products they use every day, but more than likely none of them understands the intricacies of the design and the hi-tech decorative technologies used to give each product its trendy look.
As consumer tastes change, so do the design requirements of OEMs. In order to keep up with expanding requirements, plastics injection molders are turning to in-mold decorating (IMD), a decorative technology that can give them the design freedom to keep up with popular trends and the flexibility to work with a variety of resins and product geometries.
IMD works by inserting a pre-printed polycarbonate film into a mold prior to injection. Depending on the size of the part, the film – also known as the appliqué – is inserted manually or automatically into the cavity. The resin is then shot behind the film insert, adhering it to the mold to form a finished part. Since the printed insert takes the shape of the product, IMD is particularly useful when decorating products with complex geometries such as cell phones.
When working with a design that incorporates three or more colors, IMD also can offer advantages over laser etch techniques because it reduces scrap.
One leading injection molder has been using IMD technology for more than four years to decorate multi-color applications with complex shapes. The OEM's design goals have been to keep costs low and bring more style to its products. The flexibility of the IMD process also has allowed the OEM to achieve multiple product models using one mold by simply changing appliqués.
Of course, a product's shape and desired colors must be taken into account when using IMD. In addition, it's important to realize that loading the appliqués into the mold can cause some defects. If the mold is loaded by hand, molders run into the same problems associated with a typical semi-automatic process. Ideally, molders should load with a pick-and-place robot, which will allow them to run in automatic modes and yield more consistency with fewer defects.
The placement of the gate – the channel through which the plastic resin flows into the cavity – is also a consideration in the IMD process. When using IMD, it is necessary to fill the back side of the appliqué with plastic by placing the gate behind the appliqué to prevent material from getting in front of the part and causing a defect.
One of the most appealing advantages of IMD is cost. Unlike paint and laser decoration, which require multi-million dollar paint lines, IMD is considered to be fairly cost-effective because it uses conventional molding machines, even though molders may need to invest time in secondary equipment to load the appliqués into the tool. Since the decoration occurs as the part is being molded, IMD also eliminates additional costs that must occur after the product is molded. The only other additional costs the OEM should be aware of are the costs of tools required to create, shape, and cut out the appliqué from raw stock.
As OEMs work with their supplier to examine if IMD is a cost-effective solution, the deciding factors will rest primarily on the product volume and number of colors incorporated. Most injection molders using IMD require a purchasing volume of 100,000 per year. One manufacturer, however, has a process suited for low-volume products. The proprietary process requires pre-printing a design on a sheet of polycarbonate film, cutting the film into shape, and inserting the film into the mold. Depending on the complexity of the part, the film can be formed accordingly. The advantage of this is OEMs can stock the basic product and then diversify for different applications without retooling or redesigning the part.
More information is available by contacting United Plastics Group, UPG Corporate Headquarters, 900 Oakmont Ln., Ste. 100, Westmont, IL 60559, calling (630) 321-5500, writing in 300 on our reader service card, visiting www.unitedplasticsgroup.com, or replying online at www.pddnet.com.
Caption:These cell phone lenses feature a decorative process known as in-mold appliqué.
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