The same economic and functional advantages that make in-mold labeling (IML) a growing trend in injection molded packaging are expanding its uses in large parts for durable goods as well. A striking example of the latter is IML’s use to decorate exterior panels for motorcycle racing bikes. The Yamaha MotoCross and SuperCross bikes sport three IML parts that benefit from lightweighting, improved aesthetics, greater durability, and labor savings through eliminating secondary operations.
IML FOR WEIGHT REDUCTION
IML in injection molding has been used predominately for rigid packaging, mostly in Europe. In North America, IML is picking up steam in packaging and has been used for some time on a limited scale for durable goods such as toys and a few larger parts such as safety labels on tractors, lawn/garden equipment, and snowmobiles (see Learn More).
The Yamaha parts are further proof that IML is not only for packaging but also for durable goods, and large ones at that. This is believed to be the first use of IML in motorcycle parts. Two decorated polypropylene radiator shrouds for the racing bikes measure 21 × 13 in. while the PP number plate is 13 × 13 in. Motorcycle manufacturers constantly strive to cut weight, and “every pound they save means improved performance,” according to James Priestnal, general manager of Cycra Racing, a designer and molder of motorcycle parts and accessories in Hebron, Ohio.
The large sponsorship logos are printed on an in-mold film label that becomes an integral part of the product, rather than resting on the outside of the part like the previous pressure-sensitive 12- to 18-mil-thick vinyl labels. The switch from the standard heavy vinyl labels helped shave 2.2 lb from the bike’s weight. The lighter labels provide much of the weight savings, and thin-walling to compensate for the mass of the label also cuts weight. Another key benefit is the permanence of the in-mold label, which can withstand damage from road debris and power washing.
“We’re in-mold labeling large parts and ones that take the most abuse,” says Priestnal. “We selected large parts for the weight savings and parts that are often hit by debris, making them most prone to label peeling.” Power washing is used to clean mud off the bikes. “When you power wash the bike, the vinyl labels can come off.”
The label is made of GraFilm, a 7-mil microporous plastic film (composition is proprietary) from Fusion Graphics Inc. For durable goods, Fusion Graphics prefers to call the process “in-mold decorating” or IMD. The labels reportedly adhere well to all thermoplastics and thermoset FRP composites. No tool changes are required to accommodate the labels.
The parts are molded in one cavity on a 450-ton Milacron press. Cycra molds just 200 sets of the radiator shrouds and number plates for Yamaha. Because this is a low-volume application, the labels are placed by hand in the press and are electrostatically charged so they stick to the mold.
GraFilm is also used for IML packaging. Fusion Graphics is developing enhanced grades for anti-counterfeiting in pharmaceutical packaging.