Page 39 - MetalForming November 2019

The Roper Corp. plant expansion in Fayetteville, GA, accommodated two new transfer presses, enabling the plant to increase its metal fabrication capability as part of a program to insource metal parts. GE Appliances reports that it invested $43 million to create new manufacturing capacity and products at the plant. Photo courtesy of GE Appliances
ing to a trip to the scrap pile, according to Ulintz.
“We thought it was a material issue when in fact it was this inconsistency in lubricant application,” he says.
Another challenge, Ulintz points out, when employing polyethylene sheets: the need to remove them imme- diately following the stamping process, as a delay following forming would make doing so very difficult.
“And,” he says, should these sheets and parts be exposed to ultraviolet light while sitting around for any length of time, the sheets could not be removed at all. A stamper may decide to do all of the initial forming first, then set that part run aside while changing tooling for another operation. But the poly- ethylene sheets will stick.”
Of course, dirt and grit and other impurities must be minded throughout the entire part-production process so as not to mar the part material.
“Blank washing becomes an impor- tant process,” Ulintz says.
After producing a blank, good prac- tice includes transfer to a blank-wash- ing process for removal of any particles or impurities prior to forming. This also helps prevent damage to those highly polished dies.
When deep-drawing Class-A parts, Ulintz recommends employing forming simulation and the use of draw beads. Even for shallow drawn parts, his draw- bead recommendation stands.
“Draw beads help ensure a nice, tight panel without wrinkles or waves,” Ulintz says. “Make sure that the mate- rial going over the draw beads doesn't end up in the part and, instead is trimmed away.”
Be sure to stretch material when forming panels, Ulintz advises, to pre- vent loose metal that creates waves that may not be visible until secondary painting operations.
And of course, protection of Class- A material and parts demands careful material handling throughout the plant.
“Today, automation handles a lot of Class-A surface material,” according to Ulintz. “Vacuum cups may pick and place material into the die, for example.” MF
ume suppliers.
Finally, as global markets have
increased the number of standards, each country has their own variation of safety specifications. This can add significant SKUs. American Trim accommodates all new and existing requirements on behalf of its OEMs and Tier customers.
Tooling Up for Class-A Finishes
Styling demands much across the appliance-manufacturing chain, with tooling bearing the brunt. A single sur- face imperfection can relegate appli- ances to the scratch-and-dent sale sec- tion of a department store, or, more likely, result in scrap and wasted pro- duction time in a manufacturing facility.
To find out what it takes to produce Class-A parts and components at vol- ume quantities (hint: the key word is “careful”), we talked to Pete Ulintz, author of the Tooling by Design column in MetalForming, and technical director at our parent organization, the Preci- sion Metalforming Association.
“Super-duper careful,” Ulintz says, stressing the importance of delicate material handling when producing vis- ible appliance panels and parts. Mate- rial handling in stamping not only includes transport and storage of such parts, but how the material is handled along the press line and in the die.
“Consider the condition of the tool-
ing,” Ulintz advises. “Tooling for Class- A parts will require highly polished sur- faces and the use of high-quality lubri- cants. When I was involved with stamping Class-A components, albeit stainless steel parts that included post- process nickel plating and clear chroming, we applied a polyethylene sheet to both sides of the blank, which provided an added level of protection against imperfections such as scratches and dirt. The sheet also served as a lubricant.”
Interestingly, employing the sheet in addition to a lubricant can introduce a unique situation, as Ulintz recalls.
“Through some testing for another Class-A project, we found that the lubricant would not apply consistently, sometimes puddling or, otherwise not be evenly distributed,” he says. “The lubricant must be compatible with the material covering the sheet metal...a wetting agent may be required so that it would adhere. We couldn't achieve consistent results due to the uneven lubricant distribution, which caused variability in production. Sometimes we would produce a good part with a nice surface finish, and other times the part stretched too much, causing the grains to enlarge in localized areas and producing a dull surface.”
A dull area in the stainless steel part would, upon nickel plating and chroming, stand out even more, lead-
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