Assembling Medical Devices Using the Walking Beam System | May 01, 2013 | Assembly magazine

        Farason Corp. has been designing and manufacturing automated assembly systems for over 25 years. The company, headquartered in Coatesville, Pennsylvania, develops automated systems for food, cosmetics, medical devices, pharmaceuticals, personal care products, toys, and solar panels. The company’s client list includes Blistex Inc., Crayola Crayons, L’Oreal USA, Smith Medical, and even the US Mint.
        Pharason was recently approached by a medical device manufacturer who wanted to develop a system for assembling two cylindrical plastic parts. One part is inserted into the other and the assembly snaps into place. The manufacturer requires a capacity of 120 components per minute.
        Component A is a vial containing a substantially aqueous solution. The vials are 0.375″ in diameter and 1.5″ long and are fed by an inclined disc sorter that separates the parts, hangs them from the larger diameter end, and discharges them into a C-shaped chute. Parts exit onto a moving conveyor belt lying on its back, end-to-end, in one direction.
        Component B is a tubular sleeve to hold the vial for transport to downstream equipment. The 0.5″ diameter, 3.75″ long sleeves are fed by a bag-in-disk sorter that sorts the parts into pockets that are radially located around the perimeter of a rotating plastic disk. Pockets are contoured to match the shape of the piece. Banner Engineering Corp. Presence Plus Camera. installed on the outside of the bowl and looks down at the details passing under it. The camera orients the part by recognizing the presence of gearing at one end. Incorrectly oriented components are thrown out of the pockets by the air stream before they leave the bowl.
        Disc sorters, also known as centrifugal feeders, do not use vibration to separate and position parts. Instead, they rely on the principle of centrifugal force. Parts fall on a rotating disk, and the centrifugal force throws them to the periphery of the circle.
        The bagged disc sorter is like a roulette wheel. As the part slides radially away from the center of the disk, special grippers along the outer edge of the disk pick up the correctly oriented part. As with a vibrating feeder, misaligned parts can get stuck and come back into circulation. The tilted disc sorter works in the same way, except that it is also assisted by gravity because the disc is tilted. Instead of staying on the edge of the disc, the parts are guided to a specific point where they line up at the exit of the feeder. There, the user tool accepts correctly oriented parts and blocks misaligned parts.
        These flexible feeders can accommodate a range of parts of the same shape and size by simply changing fixtures. Clamps can be changed without tools. Centrifugal feeders can deliver faster feed rates than vibrating drums, and they can often handle tasks vibrating drums cannot, such as oily parts.
        Component B exits the bottom of the sorter and enters a 90 degree vertical curler which is redirected along a rubber belt conveyor perpendicular to the direction of travel. The components are fed into the end of the conveyor belt and into a vertical chute where the column is formed.
       The moveable beam bracket removes component B from the rack and transfers it to component A. Component A moves perpendicular to the mounting bracket, enters the balance beam, and moves parallel to and next to the corresponding component B.
        Movable beams provide controlled and precise movement and positioning of components. Assembly takes place downstream with a pneumatic pusher that extends, contacts component A and pushes it into component B. During assembly, the top containment holds assembly B in place.
        To match performance, Farason engineers had to make sure that the outer diameter of the vial and the inner diameter of the sleeve matched tight tolerances. Farason Application Engineer and Project Manager Darren Max said the difference between a properly placed vial and a misplaced vial is only 0.03 inches. High speed inspection and precise positioning are key aspects of the system.
        Banner’s laser measuring probes check that components are assembled to the exact overall length. A 2-axis Cartesian robot equipped with a 6-axis vacuum end effector picks up components from the walking beam and transfers them to a fixture on the feed conveyor of the Accraply labeling machine. Components recognized as defective are not removed from the walking beam, but fall from the end into a collection container.
       For more information on sensors and vision systems, visit www.bannerengineering.com or call 763-544-3164.
        Editor’s Note: Whether you’re a system integrator or an OEM’s in-house automation team, let us know if you’ve developed a system that you’re particularly proud of. Email John Sprovierij, ASSEMBLY editor at sprovierij@bnpmedia.com or call 630-694-4012.
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Post time: Mar-29-2023