Conveyor network moves fine-blanked clutch plates unspoiled.
Making precision stamped parts and maintaining their quality through subsequent processes and handling is difficult. With each new process, or each time a part is handled, the risk of damage to its surface increases.
Recently, Atlas Automation installed an automated production system in a major US automaker's plant to handle clutch plates as they pass from operation to operation. The parts are formed by a fine-blanking press to extremely tight tolerances (with no burrs). Then they are abrasive finished and washed to remove abrasive compound and metal fragments.
As part of the system, Atlas configured a two-lane conveyor network that delivers parts to individual machine conveyors at a rate of 2400 pcs/hr. As parts leave the press, the conveyor network first takes them in and out of two successive abrasive-finishing machines (AFMs).
Between the AFMs, each part is turned over by a waterfall drop to expose its opposite side. Once the part is flipped, it travels to the second AFM, and then to the washer, which removes any remaining oils and abrasive compound.
Finally, parts travel to an accumulation area, where specially designed fixtures receive them as they complete their route. These spike-like fixtures are designed to prevent parts from hitting one another. As each piece falls onto the fixture, it cannot nick the surface of the previous part.
When 25 parts have been loaded onto a given fixture, it indexes forward to position the next fixture. Meanwhile, a tending operator unloads the stacks. If he's unable to unload them immediately, the system can load up to 36 stacks before it shuts itself down.
Before installing the Atlas system, the automaker often had problems with part quality. Instead of the special fixtures, he used a lazy Susan onto which parts were pushed when complete. This allowed them to bump against one another, nicking surfaces in the process. In addition, parts were unloaded randomly, making it impossible to maintain a first-in/first-out (FIFO) inventory system.
The new equipment, however, allows the manufacturer to maintain a FIFO system. Fixtures are loaded and unloaded in a predetermined order. And, because each fixture holds 25 parts (about 5" high), QC personnel can easily inspect parts systematically. That is, by checking the quality of the part on top of the stack, the inspector can detect variations in quality from stack to stack--every 25 parts.
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|Publication:||Tooling & Production|
|Date:||Oct 1, 1989|
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