Page 16 - MetalForming July 2012

Less Lube,
Less Cleaning,
Better Paint Job
The numerous formed crevices on these casement-window operator-track stampings can’t help but trap lubricant, and residual lubricant buildup caused paint defects that cost Truth Hardware more than $20,000 in scrap in 2011.
firm upgraded its stamping-lubricant delivery systems to a more readily con- trolled and programmable fluid-deliv- ery setup. As a result, it has complete- ly eliminated paint defects on the track sections, and easily justified the invest- ment to outfit all 11 of its progressive- die presses with the programmable lube system, according to Miller.
Lube Consumption Slashed
Truth Hardware maintains an inven- tory of some 500 dies. Presses are 75- to 300-ton Minster models, the latest a 200-ton press purchased in 2000. The firm takes in coils of mild and high- strength-low-alloy (HSLA) steel, as well as stainless steels in the 200-, 300- and 400-series alloys. Strip measures 1⁄2 to 175⁄8-in. wide.
Stainless steel represents 15 percent of the firm’s stamped-parts volume, and continues to become more and more popular with customers. As such, Miller notes a handful of key adjustments made in the toolroom to accommodate stainless vs. carbon steels. These include opening up die clearances from 10 per- cent for carbon steels to 12 to 14 percent for stainless; the use of powdered-metal tools steels for stamping of stainless steels; and fine-polishing of form tools used in stainless-steel applications.
In addition to focusing on improving the quality of its stainless-steel stamp- ings, as noted above Miller and his peers have long-sought a better solution to managing consumption of die lubricant.
“In 2000,” recalls Miller, originally
The pressroom at Truth Hardware, Owatonna, MN, produces hun- dreds of various stamped window- hardware parts, in volumes measured in the millions. One family of stamped parts in particular recently caught the attention of manufacturing engineer Joe Miller and his cohorts: casement-window operator track. Track sections are stamped from 15.5-in.-wide steel strip 0.035 in. thick, in 13 1.5-in. progressions. To say the sections have a lot of formed crevices would be an understatement (see the photo), and any excess stamping lubricant can’t help but become trapped in those crevices.
“It’s a big runner for us,” says Miller, emphasizing the importance of the job to the company. “The dies making those parts run every day, turning out parts at 40 strokes/min., with annual volumes of more than 2 million.”
As the track parts do not need further secondary finishing before heading to the firm’s paint department, residual lubricant buildup often became a thorn in the company’s side. Excess lube unable to reliably be removed during cleaning, caused paint defects that cost the firm more than $20,000 in scrap in 2011.
To tackle the problem head-on, the
14 MetalForming/July 2012
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...and that’s the truth.
BY BRAD F. KUVIN, EDITOR