Isn’t Dead
ing Manager Dan Rauwald, part of the company’s daily decision-making process involves selecting the best manufacturing process or processes to serve customers’ needs. Casting is not always the optimal selection. Tube-shaped products generally are best produced via the extrusion pro- cess. Many shielding assemblies are fabricated most effi ciently using sheet lead or lead coil. But for a handful of applications, casting is ideal. One of the oldest applications for
cast lead is in counterweights. Because of its inherent density (Table 1) and lower price tag than other dense mate- rials like tungsten, gold, and platinum, lead often is the material of choice when a heavy material is needed within tight confi nes. “The benefit of a lead counter-
weight, versus one made from iron, steel or concrete, is more space where you want it and less where you don’t,” Ray said. “For example, if you own a cold-storage facility, you are paying for cooling the entire square footage. Lead aids the design of a compact forklift with a tight turning radius. So, what would otherwise be needed traffic space can be converted into revenue- producing storage space.” According to Herb Doyle, a spokes-
person for Belmont Metals Inc., Brook- lyn, N.Y., lead counterweights are particularly suited to aerospace ap- plications, where tight spacing and packaging requirements mean the smallest, most intricate weights pos- sible are required to fi t into the space. “The density of lead can’t be re-
placed with anything else,” Doyle said. “Critical applications, like airfoils, need a certain density to counterbalance them. Also, they are rather compli- cated, and you need something fl uid, like lead, to fi ll those cavities.” Again due to its density, lead is also
perfectly suited to a large number of radioactivity shielding applications. (Think of the heavy apron draped over dental patients during x-rays.)
JULY/AUGUST 2011
Many lead products producers like Vulcan Global Manufacturing Solutions maintain in- house metalcasting capabilities. The material is generally cast in the permanent mold (shown) or diecasting process.
METAL CASTING DESIGN AND PURCHASING 35
Castings are used in some of these. “We cast a variety of shielding prod-
ucts for OEM equipment,” Ray said. “X- ray machines, CT scanners and things along those lines. We also serve the medi- cal, security, nu- clear pharmacy and aerospace markets.” Medical and
applications as explosion-directing devices. The dense materials are nec- essary to contain and focus the force of blasts used for material extraction. Lead also
Around 8 million metric tons of lead were used in 2010, up from about 6.5 million metric tons in 2000.
nuclear phar- macy products include vessels for bio-waste and radioactive materials, the more complex of which are cast before being set into plastic housings. Lead castings also are found in mining
of fers high damping char- acteristics and can be called on for parts re- quired to limit vibration. Tony Cremers, presi- dent of proto-
type specialist Craft Pattern and Mold, Maple Plain, Minn., said his company helped one customer seeking a one-off lead part to limit the jarring feel of a commercial lawnmower.
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