Page 27 - MetalForming June 2009

VCI pioneer and packag- ing supplier based in Alsip, IL.
“George Daubert, our
company’s founder, was
contracted by the military
to provide corrosion-pre-
ventive methods for muni-
tions and arms slated for
storage after World War
II,” explains Simpson. “He
invented this VCI technol-
ogy under contract to the
U.S. Navy. The standard
back then was to use heavy
oil or grease to protect the
surfaces of stored metallic
parts. Obviously, those
kinds of products needed
to be removed before the
parts could be put back
into operation. Research
focused on developing
means to lighten the oil or
eliminate it completely so
that parts could be removed from pack- aging and placed immediately into oper- ation or undergo further processing.”
VCI protection can function on high and low volumes of parts large and small. Take electrical connectors for example.
“Suppose a metalformer produces connectors from strip steel or copper or even silver-plated strip,” offers Simpson. “A strip of VCI paper can be fed onto a roll as an interleaf that delivers chemi- cals to the metallic parts. So as these fin- ished connections are rolled into a coil, the thin strip of VCI paper feeds in with the coil and provides continuous protection throughout the length of that coil, ensuring corrosion-free parts throughout shipment and storage.”
Fineblanked parts yield a more tra- ditional mid-volume application, according to Simpson. “Consider the stamper that stacks several hundred fineblanked parts—about as large as your hand—into a bulk crate,” he says, “lined with a VCI bag. The bag, con- structed of low-density polyethylene, is impregnated with VCIs that protect those parts that contact the bag as well as parts in proximity to the bag.
plex packaging design, with a number of VCI barrier layers along with VCI emitters placed inside the package.”
Some Homework Required
A VCI formulation functioning ideally under one set of conditions may not work under another, according to Daubert Cromwell officials. The success of a VCI applica- tion rests upon:
• Which materials are in need of protection;
• Corrosion inhibiting chemicals used and their effec- tiveness on the materials;
• Ratio of chemicals in the formulation;
• Amount of VCI on the paper or in the film;
• pH of the finished product;
• Water solubility and effectiveness of the corrosion inhibitor in the presence of moisture and high humidity; and
• Overall packaging design and con- ditions expected during packing, ship- ping and storing.
Deciding on the right VCI protection also demands consideration of the length of protection required, climate conditions for storage and transport, size and weight of parts, chemicals or residues on the parts, current process- ing and cleaning methods, and prox- imity of packaging-station location to other processes.
A supplier to metalformers looking for VCI protection also will discover whether parts will be shipped domesti- cally or internationally.
“Obviously, international shipping demands increased protection because the parts will be exposed to more severe elements over a longer period of time,” says Simpson, noting that a number of paper and plastic-film pack- aging solutions are available to fit a metalformer’s current packaging process and can be introduced easily into its operations. MF
A plain poly bag lines the crate and contains the VCI.
Interleaves of VCI paper protects parts above and below, in the contact and vapor phase.
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METALFORMING / JUNE 2009 25
To protect large metal stampings from corrosion during shipment and storage, the stamper lines the crate with a low-density polyeth- ylene bag impregnated with VCIs that protect the parts that contact the bag as well as parts in proximity to the bag. Interleaves or paper or film VCI sheets may be added, laid at intervals as the parts are stacked to ensure delivery of enough VCI to protect parts in the cen- ter of the crate.
Interleaves or paper or film VCI sheets may be added depending on the size of the crate, laid at intervals as the parts are stacked to ensure delivery of enough VCI to protect parts in the center of the crate. Just close the bag and crate for shipment. So, VCI pack- aging is not terribly different from what is done with conventional pack- aging materials.”
Part size represents no limitation for VCI applications, making the protection viable for large components and assem- blies, and various alloys can be pro- tected within a single bag. Attesting to those facts, Simpson notes that Daubert Cromwell has even wrapped complete engines for export.
“The engine is placed in a VCI bag along with one or two VCI emitters that add more chemicals for improved or prolonged protection,” he says. “The engine may have parts made from var- ious alloys or featuring zinc-galva- nized or phosphate coatings, and the engine block itself may be cast iron. All of those metallic species need protec- tion within that bag, requiring a VCI composition that will actively protect each one. That may require a com-