Page 30 - MetalForming December 2009

George Keremedjiev has been writing this column for more than 20 years. He regularly consults with metalforming companies worldwide and provides metal- formers with training on the appli- cation and implementation of sen- sors for die protection. For more information on his seminars and consultancies, contact:
Tecknow Education Services, Inc. P.O. Box 6448
Bozeman, MT 59771
phone: 406/587-4751
fax: 406/587-9620 www.mfgadvice.com
E-mail: gk@mfgadvice.com
There is a misconception brewing within some of our metalforming companies regarding the uses of electronic sensors in today’s low-volume parts orders. Some are of the opinion that since low volumes generally mean more single-stroke tooling and less automatic progressive dies, that it fol- lows that the implementation of elec- tronic sensors simply is not needed or at the very least their use should be min- imized. Nothing could be further from the truth. In fact, single-stroke tooling needs to include electronic sensors because the process relies primarily on a human operator (or a robotic arm) to place the blank properly within the tooling.
What assurances does one have that the operator placed the blank properly within the tool? The same for a robot- ic arm—how does one verify that the workpiece is nested properly within the die? Surely closing a die on a misfed blank can be equally catastrophic whether that blank is hand-fed or auto- matically placed by a robot. This is especially so when the location of fea- tures, such as for holes, tabs, notches and the like, needs to be precisely posi- tioned. The subject of proper feeds within a progressive die or a single- stroke tool are exactly the same, both require proper blank placement within the tool’s work areas. There is no dif- ference among manual, robotic or pro- gressive fed tooling in terms of the need to patrol proper workpiece placement.
There also are some who argue that in a manually fed, single-stroke tool there is no need for part-out sensing as is usually the case with automatic pro- gressive dies. Wrong again. In many cases involving manually or robotically
removed parts, the need for part- removal monitoring is much more important.
Picture this scene, which I actually witnessed in person. Your competent single-stroke press operator has been performing well for many years and now has been asked to mentor a newly recruited press operator trainee. In comes this new employee who shad- ows the experienced operator, but for whatever reason does not fully grasp how the tooling actually works. To the employee the blank is fed into this device that then closes and makes the necessary features on the blank.
I recently was being given a tour by the plant manager of a stamping com- pany where this situation was in progress. The trainee, after enough shadowing, was trusted to run the sin- gle-stroke tool and its press without supervision. The plant manager and I entered the area where the operator was working and were startled to see the operator with a confused and pained look. This recently trained individual told us that there seemed to be some magical activity going on inside the tooling. The operator then proceeded to place the blank in the tool followed by the single-stroke cycling of the press. “Look,” the operator exclaimed, “It is magic, I feed the blank into the die and the part mysteriously disappears when the die opens. I’ve done it a few times now and each time the part is gone!”
The plant manager and I instantly knew what was going on. The plant manager grabbed the arms of the newly anointed operator and prevented one more blank from being fed into the tool. We then moved closer to the open tooling and looked inside. There it
METALFORMING ELECTRONICS GEORGE KEREMEDJIEV
Low Volumes and Tooling Sensors
This CD-ROM presents dozens of George’s columns as well as papers and exclusive new presentations covering all aspects of die protection and part-quality inspection, starting and maintaining sensor programs, the role of controls in in-die sensing, and the benefits of a sound sensor program. Order it online at www.metalformingmagazine.com.
28 METALFORMING / DECEMBER 2009 ONLINE
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