Page 34 - MetalForming September 2015

Clamps Gain a Grip on Die-Change Efficiency
used for all startups, changeovers and shutdowns;
• Nurturing a culture of safe practices;
• Building a robust safety-training program for new and temporary employees;
• Properly maintaining equipment and keeping work areas clean; and
• Ensuring proper ergonomics for workers with differing physical abilities. “We developed 29 different initia- tives to improve those six target areas,” explains process engineer Ted Webb, press-shop capability coach and a member of the primary project team. “Among them were several action items targeting die changes, including creat-
ing a die-setter job description.” Chief among the die-change-related action items was improving the process for die clamping and unclamping. Challenges here included ensuring consistent torque when tightening bolts, and finding a tightening/untight- ening method independent of operator
size and strength.
“We’re averaging more than 100,000
changeovers per year,” says Stewart. “On our six-press stainless line, for example, we might change each press 50 times per week—offering a huge opportunity for increasing efficiency.”
Die-Clamping Solution Unearthed at FABTECH
The plant’s press-shop team took its mission to improve die-change effi- ciency to FABTECH 2014 in Atlanta, and struck gold at the booth of Carr Lane Roemheld Mfg. Co. That’s where Stewart and his team discovered Hilma hydromechanical clamping nuts that, when compared to traditional T-bolts, require a fraction of the torque to secure a die. Soon after returning from the exhibition, Stewart submitted a purchase order for dozens of the Hilma nuts.
“In all, we’ll invest several thou- sands of dollars per press to employ the hydromechanical nuts,” he shares. “And we plan to put them on every press. That’s a big investment (360 clamp nuts, rated to 22,400 lb. of clamping force, along with 360 1- by 6-in. bolts),
Using the new clamping nuts, which fit in 90 percent of the facility’s dies without requir- ing modification, couldn’t be simpler. The setter slides the T-bolts and clamping nuts into the slots on the press bed, then hand-tightens the nuts to secure them against the die. He then makes one or two turns with a 6-in. ratchet to reach the required torque.
32 MetalForming/September 2015
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but we expect immediate payback in terms of time savings and ergonomic advantages. The new clamping nuts have decreased our die-change times by at least 4 min. per change.”
An added bonus with the new nuts: They will fit 90 percent of the facility’s dies without modification, fitting into existing die slots. And, the nuts lend themselves to a more organized die- change procedure. The project team created Creform (Greer, SC) kitting carts at each press to organize and store the nuts. In this way, the die set- ters have visual cues that eliminate any chance that a nut either is missing from the die (during die setting) or remain- ing in the die (during die removal).
“Half of our dies were not designed inhouse; they came from other facili- ties,” adds Webb, “which created a chal- lenge when we looked at standardizing on quick-change equipment. For exam- ple, we couldn’t find another mechan- ical solution, or a magnetic system, that would work with such a high per- centage of our dies when taking into consideration the frequency at which we change dies, and our vast range of
die sizes (as large as 9 ft. long and 4 ft. wide).”
No Chance for Error
The plant’s mission to add the hydromechanical nuts to its presses kicked off this past May when it added 72 of the nuts to the stainless line, another 72 sets were added to a wrap- per line at the end of June, and Stewart filed another purchase order to outfit more presses by the end of Septem- ber.
“The die setters love the new clamp- ing nuts,” Stewart says, “and I can’t wait to get them on all of the presses. We’re eliminating opportunities for die dam- age, and we’re reducing our changeover times.
“Using the nuts couldn’t be sim- pler,” Stewart continues. “The setter slides the T-bolts and clamping nuts into the slots on the press bed, then hand-tightens the nuts to secure them against the die. He then makes one or two turns with a 6-in. ratchet to reach the required torque. A button pops on the nut at that point—no chance for error.” MF