FORMING AND FABRICATING AUTOMATION
2.2: Sheet
This large front-of-line blank feeder features a gantry pick-and-place loader to perform blank destacking, along with an integrated blank cleaner/lubricator, a vision system to capture blank orientation, and robots to properly position each blank onto the load table.
Blank Feeding—Why & When? B lank feeding certainly can complicate things and require increased capital investment, yet improved material utilization and the ability to cost- effectively produce complex parts can lead to a quick return on investment. And, feeding blanks allows stampers to continuously run their presses, optimizing overall equipment effectiveness. MetalForming wanted to better understand why and when some metal stamping facilities may opt to feed their presses with blanks (whether cut inline or offline) rather than coil, so we posed the question to Paul Stirrett, vice president of sales at Linear Transfer Automation. “We hear this question all the time,” Stirrett says. “Blank feeding certainly can complicate things and require increased capital investment. Often, the bottom line in the decision to feed blanks rather than coil comes down to material utilization and scrap costs. And certainly, in automotive and even appliance, some large class-A parts typically are blank-fed simply due to their size.”
Decision Depends on Speed, Flexibility Placing destackers at the entry side of a press—or “front-of- line automation” as automotive OEMs call it, says Stirrett—re- quires stampers to select one of two methods for moving the blanks into the press: a gantry setup with overhead magnetic or vacuum tooling, or robots. The decision usually comes down to blank geometry, available real estate and material type, and the required amount of speed and flexibility, Stirrett says, adding that, “with robots taking blanks from the destacker to the press, the stacks don’t need to be as precise as with a gantry setup. We adapt vision technology to the robot to check blank position and signal the required adjustments to ensure that the blanks precisely enter the press, as needed. However, with robots we
can typically only run a transfer press at 15 to 20 strokes/min.” Want to run faster? That’s where gantry setups shine. “These simple two-axis gantry motion systems can allow a transfer press to top out at 30 strokes/min. or more,” Stirrett says, not- ing that instead of a vision system to orient the blanks coming from the stack, “we either ensure that the blank stack is set up as required on the handling system, or use vision and other dedicated equipment to identify and adjust each blank to pres- ent it to the transfer tooling. These setups include a physical mechanism able to stop the blank as it feeds on a conveyor and crowd it into position using a series of independently ad- justable pins.”
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