|Insert molding puts a soft, vinyl bead on the edge of Kodak's SureSoft intraoral X-ray film to make patients more comfortable during a dental exam. The vinyl bead weighs a mere 0.27 gm and has a diameter of only 1.1 mm.
Now the Dental Products Business of Eastman Kodak Co. has added a delicate edge to cushion its SureSoft intraoral X-ray film.
The company sandwiches X-ray film, paper, and foil between protective vinyl-film outer layers. After sealing the layers together, a die cuts the packets leaving a tiny border of exposed vinyl to serve as an adhesion site for the cushioning bead. A robot places the packets into a multicavity insert mold. A soft vinyl compound, Apex 3208-80-NT, from Teknor Apex, Pawtucket R.I. (www.teknorapex.com), injects over the vinyl-film border.
To ensure the bead doesn't detach from the packet, Kodak narrowed the already close dimensional tolerances to give a more consistent footprint on which the incoming molten vinyl could adhere to, says Michael McGovern, Kodak's R&D technical spokesman. Also critical was careful handling of the packets throughout the injection molding process so the X-ray film isn't damaged. Balancing of material flow into the different cavities ensures uniform fill.-- Jean M. Hoffman