Assembly in Action: Conveyor Maximizes Space Usage, Efficiency
June 2, 2008
Ophthonix Inc. (Vista, CA) manufacturers iZon high-resolution eyeglass lenses, featuring a kind of optical “fingerprint” technology called iPrint. Although the company initially considered outsourcing the production of the lenses, in the end it decided it needed to do the work in-house. This, in turn, required the creation of an all-new production facility to perform the requisite forming, cutting and assembly that goes into each multi-layer lens.
Among other requirements, Ophthonix wanted a system that would be easily scalable, so that it could adjust to future production needs. The system also needed to fit into a relatively small 10,000-square-foot building, which meant it would be necessary to take advantage of vertical space as well horizontal.
Central to the resulting system is a modular, pallet-based VarioFlow conveyor system from Bosch Rexroth Corp. (Buchanan, MI), which carries the lenses to the workstations comprising the production process. Each iZon lens is made up of three layers: a back layer developed according to a customer’s unique iPrint; a middle layer that incorporates a photo-refractive polymer; and a front layer that enhances structural integrity.
Ophthonix fabricates and assembles these layers using an autotaper, an autoblocker, two lens generators, a pair of lens polishers and a number of assembly stations. Eventually, the company hopes to employ two autotapers, six autoblockers, six generators, 12 polishers and four robotic edgers.
To initiate the process, an operator first enters the patient’s iPrint data into the system’s “tray-up” prep area. A corresponding barcode is then attached to a customized tray, which is loaded with a blank and placed in a de-stacker that holds 10 trays. The trays are then released automatically onto the production line.
During production, an autotaper first positions a protective tape on each lens, after which an autoblocker processes it according to the required prescription. Once this is done, the VarioFlow’s variable-speed drive slows the pallet from 45 fpm to a much slower 3 fpm, providing it with a 25- to 45-minute cooling off period. After cooling, the lens undergoes more shaping and polishing, after which it receives a proprietary protective layer and is delivered to a series of assembly, inspection and packaging stations.
In addition to its variable-speed capabilities, the VarioFlow’s UltraCurve design minimizes friction and allows the pallets to accumulate in its curved portions. This is important in the Ophthonix application because of the limited amount of production space. In all, the system includes approximately 40 horizontal curves, ranging from 45 to 180 degrees.
UltraCurve technology also reduces the number of drives needed to power the system, reducing both up-front costs and overall power consumption.
“Most labs are loaded with carts and people, and the entire process works in batches,” says Ophthonix vice president of operations John Lemperle. “With the Rexroth VarioFlow conveyor system and automated equipment, there is now a constant and continuous flow. We’ve noticed our product cycle time is now approaching the process time of the equipment. Quality is improving daily, currently putting us at a 90 percent yield range…. If this process was done manually, we would need more people and a facility twice as large.”
For more on conveyor systems, visit www.boschrexroth-us.com or call 800-739-7684.